A number of plant pathogenic species of Phytophthora are known to produce different classes of secretory proteins during interactions with their hosts.Although several small cysteine-rich(SCR)secretory proteins,conser...A number of plant pathogenic species of Phytophthora are known to produce different classes of secretory proteins during interactions with their hosts.Although several small cysteine-rich(SCR)secretory proteins,conserved in oomycete pathogens,have been identified in Phytophthora,their specific involvement in these interactions remains unknown.In this study,an SCR effector encoded by Pn SCR82 in P.nicotianae was identified and shown to have similarities to P.cactorum phytotoxic protein,Pc F(Phytophthora cactorum Fragaria).Agroinfection with potato virus X vector,Pn SCR82,was capable of inducing plant hypersensitive cell death in Nicotiana benthamiana and Solanum lycopersicum.Real-time PCR results indicated that transiently expressed Pn SCR82 in N.benthamiana leaves activated the jasmonate,salicylic acid and ethylene signaling pathways.Transient expression of Pn SCR82 enhanced plant resisitance to P.capsici.In summary,our results demonstrated that P.nicotianae Pn SCR82 elicits defensive responses in N.benthamiana and may potentially play a significant role in future crop protection programs.展开更多
Phenotypical, cytological and molecular responses of rice to the fungus Magnaporthe grisea were studied using rice cultivars and lesion mimic plants. The cultivar Katy was susceptible to several virulent M. grisea iso...Phenotypical, cytological and molecular responses of rice to the fungus Magnaporthe grisea were studied using rice cultivars and lesion mimic plants. The cultivar Katy was susceptible to several virulent M. grisea isolates, and a Sekiguchi like-lesion mimic mutant of Katy (LmmKaty) showed enhanced resistance to these isolates. Lesion mimic phenotype of LmmKaty was rapidly induced by virulent M. grisea isolates or by avirulent ones only at high levels of inoculum. Autofluorescence (a sign of an active defense response) was visible under ultraviolet light 24 h after localized inoculation in the incompatible interaction, whereas, not evident in the compatible interaction. Autofluorescence was also observed in LmmKaty 20 h after pathogen inoculation, indicating that rapid cell death is a mechanism of LmmKaty to restrict pathogen invasion. Rapid accumulations of defense related (DR) gene transcripts, phenylalanine ammonia lyase and β-glucanase, were observed beginning at 6 h and were obvious at 16 h and 24 h after inoculation in an incompatible interaction. Rapid transcript accumulations of PR-1 and chitinase had occurred by 24 h after inoculation in an incompatible interaction. Accumulations of these transcripts were delayed in the compatible interaction. These results indicate that host active defense responses occur 24 h after pathogen inoculation and that LmmKaty exhibits enhanced resistance to M. grisea. It is suggested that the autofluorescence and expression of the DR genes after heavy inoculation are important cytological and molecular markers respectively for early determination of the host response to M. grisea in the rice blast system.展开更多
The soil-borne necrotrophic fungus Rhizoctonia solani is one of destructive fungi causing severe yield losses in various important crops. However, the host defense mechanisms against the invasion of this pathogen are ...The soil-borne necrotrophic fungus Rhizoctonia solani is one of destructive fungi causing severe yield losses in various important crops. However, the host defense mechanisms against the invasion of this pathogen are poorly understood. In this study, we employed an i TRAQ-based quantitative proteomic approach to investigate host proteins responsive to R. solani using the resistant rice cultivar YSBR1. As a whole, we identified 319 differentially accumulated proteins(DAPs) after inoculation of rice plants with R. solani. Functional categorization analysis indicates that these DAPs cover a broad range of functions. Notably, a substantial portion of the DAPs are involved in cell redox homeostasis, carbohydrate metabolism, and phenylpropanoid biosynthesis, or belong to pathogenesis-related proteins, indicating that these processes/proteins play important roles in host defense against R. solani. Interestingly, all of the DAPs involved in photosynthesis and chlorophyll biosynthetic processes, and part of the DAPs involved in phenylpropanoid biosynthesis, show reduced accumulation after R. solani infection, suggesting that R. solani probably inhibits host photosynthetic system and phenylpropanoid biosynthesis to facilitate infection and colonization. In conclusion, our results provide both valuable resources and new insights into the molecular mechanisms underlying rice and R. solani interaction.展开更多
High-throughput transcriptomics technologies have been widely used to study plant transcriptional reprogramming during the process of plant defense responses, and a large quantity of gene expression data have been acc...High-throughput transcriptomics technologies have been widely used to study plant transcriptional reprogramming during the process of plant defense responses, and a large quantity of gene expression data have been accumulated in public repositories. However, utilization of these data is often hampered by the lack of standard metadata annotation. In this study, we curated2444 public pathogenesis-related gene expression samples from the model plant Arabidopsis and three major crops (maize, rice, and wheat). We organized the data into a user-friendly database termed as PlaD. Currently, PlaD contains three key features. First, it provides large-scale curated data related to plant defense responses, including gene expression and gene functional annotation data.Second, it provides the visualization of condition-specific expression profiles. Third, it allows users to search co-regulated genes under the infections of various pathogens. Using PlaD, we conducted a large-scale transcriptome analysis to explore the global landscape of gene expression in the curated data. We found that only a small fraction of genes were differentially expressed under multiple conditions, which might be explained by their tendency of having more network connections and shorter network distances in gene networks. Collectively, we hope that PlaD can serve as an important and comprehensive knowledgebase to the community of plant sciences, providing insightful clues to better understand the molecular mechanisms underlying plant immune responses. PlaD is freely available at http://systbio.cau.edu.cn/plad/index.php or http://zzdlab.com/plad/index.php.展开更多
Verticillium wilt,caused by Verticillium dahliae,seriously restricts the yield and quality improvement of cotton.Previous studies have revealed the involvement of WRKY members in plant defense against V.dahliae,but th...Verticillium wilt,caused by Verticillium dahliae,seriously restricts the yield and quality improvement of cotton.Previous studies have revealed the involvement of WRKY members in plant defense against V.dahliae,but the underlying mechanisms involved need to be further elucidated.Here,we demonstrated that Gossypium hirsutum WRKY DNA-binding protein 33(GhWRKY33) functions as a negative regulator in plant defense against V.dahliae.GhWRKY33 expression is induced rapidly by V.dahliae and methyl jasmonate,and overexpression of GhWRKY33 reduces plant tolerance to V.dahliae in Arabidopsis.Quantitative RT-PCR analysis revealed that expression of several JA-associated genes was significantly repressed in GhWRKY33 overexpressing transgenic plants.Yeast one-hybrid analysis revealed that GhWRKY33 may repress the transcription of both AtERF1 and GhERF2 through its binding to their promoters.Protein-protein interaction analysis suggested that GhWRKY33 interacts with G.hirsutum JASMONATE ZIM-domain protein 3(GhJAZ3).Similarly,overexpression of GhJAZ3 also decreases plant tolerance to V.dahliae.Furthermore,GhJAZ3 acts synergistically with GhWRKY33 to suppress both AtERF1 and GhERF2 expression.Our results imply that GhWRKY33 may negatively regulate plant tolerance to V.dahliae via the JA-mediated signaling pathway.展开更多
Plants adaptively change their cell wall composition and structure during their growth,development,and interactions with environmental stresses.Dirigent proteins(DIRs)contribute to environmental adaptations by dynamic...Plants adaptively change their cell wall composition and structure during their growth,development,and interactions with environmental stresses.Dirigent proteins(DIRs)contribute to environmental adaptations by dynamically reorganizing the cell wall and/or by generating defense compounds.A maize DIR,ZmDRR206,was previously reported to play a dominant role in regulation of storage nutrient accumulation in endosperm during maize kernel development.Here we show that ZmDRR206 mediates maize seedling growth and disease resistance by coordinately regulating biosynthesis of cell wall components for cell-wall integrity(CWI)maintenance.Expression of ZmDRR206 was induced in maize seedlings upon pathogen infection.ZmDRR206 overexpression in maize resulted in reduced seedling growth and photosynthetic activity but increased disease resistance and drought tolerance,revealing a tradeoff between growth and defense.Consistently,ZmDRR206 overexpression reduced the contents of primary metabolites and down-regulated genes involved in photosynthesis,while increasing the contents of major cell wall components,defense phytohormones,and defense metabolites,and up-regulated genes involved in defense and cell-wall biosynthesis in seedlings.ZmDRR206-overexpressing seedlings were resistant to cell-wall stress imposed by isoxaben,and ZmDRR206 physically interacted with ZmCesA10,which is a cellulose synthase unit.Our findings suggest a mechanism by which ZmDRR206 coordinately regulates biosynthesis of cell-wall components for CWI maintenance during maize seedling growth,and might be exploited for breeding strong disease resistance in maize.展开更多
Due to the hidden nature of roots in the soils, it is more challenging to investigate their resistance traits and defense responses as compared to those of the aerial organs. At the same time, it is self-evident that ...Due to the hidden nature of roots in the soils, it is more challenging to investigate their resistance traits and defense responses as compared to those of the aerial organs. At the same time, it is self-evident that root health is fundamental to a plant’s entire life and productivity. It is also easily conceivable that root function, physiology, morphology, and architecture are constantly impacted by the complex soil environment including both biotic and abiotic factors. This report summarizes and updates the challenges and progress in evaluating resistance responses of apple root to infection from a necrotrophic oomycete pathogen, Pythium ultimum. Several obstacles impede the progress of investigating apple root resistance traits including the difficulties of direct and real-time evaluation and the lack of a continuous supply of apple plants for repeated infection assays. Systematic and detailed analyses were made possible by implementing a micropropagation procedure for continuously generating uniform apple plants for repeated infection assays. As a result, an elite panel of apple rootstock germplasm with distinct resistance levels was identified. These apple rootstock genotypes with well-defined resistance levels are the much-needed plant materials for subsequent genomics and transgenics analyses to define the functional roles of specific candidate genes. Careful microscopic examination revealed contrasting necrosis progression patterns between resistant and susceptible genotypes, which shed light on the potential mechanisms underlying resistance traits. Our continuing research will provide a clearer view regarding the genetic elements regulating resistance traits in apple roots to P. ultimum infection.展开更多
Apple leaf spot,caused by the Alternaria alternata apple pathotype(AAAP),is an important fungal disease of apple.To understand the molecular basis of resistance and pathogenesis in apple leaf spot,the transcriptomes o...Apple leaf spot,caused by the Alternaria alternata apple pathotype(AAAP),is an important fungal disease of apple.To understand the molecular basis of resistance and pathogenesis in apple leaf spot,the transcriptomes of two apple cultivars‘Hanfu'(HF)(resistant)and‘Golden Delicious'(GD)(susceptible)were analyzed at 0,6,18,24 and 48 h after AAAP inoculation by RNA-Seq.At each time point,a large number of significantly differentially expressed genes(DEGs)were screened between AAAP-inoculated and uninoculated apple leaves.Analysis of the common DEGs at four time points revealed significant differences in the resistance of‘HF'and‘GD'apple to AAAP infection.RLP,RNL,and JA signal-related genes were upregulated in both cultivars to restrict AAAP development.However,genes encoding CNLs,TNLs,WRKYs,and AP2s were only activated in‘HF'as part of the resistance response,of which,some play major roles in the regulation of ET and SA signal transduction.Further analysis showed that many DEGs with opposite expression trends in the two hosts may play important regulatory roles in response to AAAP infection.Transient expression of one such gene MdERF110 in‘GD'apple leaves improved AAAP resistance.Collectively,this study highlights the reasons for differential resistance to AAAP infection between‘HF'and‘GD'apples which can theoretically assist the molecular breeding of disease-resistant apple crops.展开更多
With the development of tourism at home and abroad,Rapeseed(Brassica napus)has become an important ornamental plant.However,its ornamental value at the inflorescence stage is greatly reduced by Sclerotinia sclerotioru...With the development of tourism at home and abroad,Rapeseed(Brassica napus)has become an important ornamental plant.However,its ornamental value at the inflorescence stage is greatly reduced by Sclerotinia sclerotiorum.Identification of important genes in the defense responses is critical for molecular breeding,which is an important strategy for controlling the disease.In this study,we isolated a B.napus WRKY transcription factor gene,BnaWRKY75.BnaWRKY75 was found to encode a nucleus-localized protein and exhibited relatively high expression in the stems.Arabidopsis thaliana transgenic plants expressing BnaWRKY75 showed enhanced resistance to S.sclerotiorum,and both ProBnaWRKY75:GUS and gene expression analyses showed that BnaWRKY75 was highly responsive to S.sclerotiorum infection,indicating the involvement of BnaWRKY75 in response to this infection.Furthermore,overexpression(OE)of BnaWRKY75 in B.napus significantly enhanced the resistance to S.sclerotiorum,whereas the resistance was reduced in RNAi transgenic B.napus plants.Moreover,the BnaWRKY75-OE B.napus plants exhibited constitutive activation of salicylic acid-,jasmonic acid-,and ethylene-mediated defense responses and the inhibition of both H_(2)O_(2)and O_(2)·^(-)accumulation in response to this pathogen.By contrast,BnaWRKY75-RNAi plants showed a reverse pattern,suggesting that BnaWRKY75 is involved in hormonal signaling pathways and in the control of reactive oxygen species accumulation.In conclusion,these data indicate that BnaWRKY75,a regulator of multiple defense responses,positively regulates resistance against S.sclerotiorum,which may guide the improvement of resistance in rapeseed.展开更多
Chinese cabbage(Brassica rapa subsp.pekinensis)suffers from soft rot disease caused by Pectobacterium carotovorum(Pc).To uncover the mechanisms underlying the defense response of Chinese cabbage to Pc,we constructed a...Chinese cabbage(Brassica rapa subsp.pekinensis)suffers from soft rot disease caused by Pectobacterium carotovorum(Pc).To uncover the mechanisms underlying the defense response of Chinese cabbage to Pc,we constructed a suppression subtractive hybridization(SSH)library from Pc-infected cabbage and obtained 1919 non-redundant expressed sequence tags(ESTs),which were used for cDNA microarray.We detected 800 differentially expressed genes(DEGs)in cabbage at different time points post-Pc inoculation,which were further confirmed by quantitative real-time PCR.One quarter of these DEGs were involved in the biotic stress pathways visualized by MapMan.Among them,8,8,1,3,and 2 DEGs were related to jasmonic acid(JA),ethylene(ET),JA+ET,auxin,and abscisic acid(ABA)signaling pathways,respectively,while no DEG was detected for salicylic acid(SA)signaling.Assessment of phytohormone production in the Pc-infected leaves showed that JA and ET production was increased,while SA production was decreased.Treatment with JA,methyl jasmonate(MeJA),the ET precursor 1-aminocyclopropane-1-carboxylate(ACC),or combinations thereof,reduced the disease severity,and the JA and JA+ACC treatments were superior and performed equally well.Our findings suggest that JA and ET may act synergistically against Pc infection in Chinese cabbage,and JA-mediated signaling might be the most significant.展开更多
Triticum aestivum L. cv. Guizi 1(GZ1) is a drought-tolerant local purple wheat cultivar. It is not clear how purple wheat resists drought stress, but it could be related to anthocyanin biosynthesis. In this study, tra...Triticum aestivum L. cv. Guizi 1(GZ1) is a drought-tolerant local purple wheat cultivar. It is not clear how purple wheat resists drought stress, but it could be related to anthocyanin biosynthesis. In this study, transcriptome data from droughttreated samples and controls were compared. Drought slightly reduced the anthocyanin, protein and starch contents of GZ1 grains and significantly reduced the grain weight. Under drought stress, 16 682 transcripts were reduced, 27 766 differentially expressed genes(DEGs) were identified, and 379 DEGs, including DREBs, were related to defense response. The defense-response genes included response to water deprivation, reactive oxygen, bacteria, fungi, etc. Most of the structural and regulatory genes in anthocyanin biosynthesis were downregulated, with only Ta DFR, Ta OMT, Ta5,3GT, and Ta MYB-4 B1 being upregulated. Ta CHS, Ta F3H, TaCHI, Ta4CL, and TaF3’H are involved in responses to UV, hormones, and stimulus. Ta CHS-2D1, Ta DFR-2D2, Ta DFR-7D, TaOMT-5A, Ta5,3 GT-1B1, Ta5,3GT-3A, and Ta5,3GT-7B1 connect anthocyanin biosynthesis with other pathways, and their interacting proteins are involved in primary metabolism, genetic regulation, growth and development, and defense responses. There is further speculation about the defense-responsive network in purple wheat. The results indicated that biotic and abiotic stress-responsive genes were stimulated to resist drought stress in purple wheat GZ1, and anthocyanin biosynthesis also participated in the drought defense response through several structural genes.展开更多
Black spot disease in poplar is a disease of the leaf caused by fungus. The major pathogen is Marssonina brunnea f. sp. multigermtubi. To date, little is known about the molecular mechanism of poplar (M. brunnea) in...Black spot disease in poplar is a disease of the leaf caused by fungus. The major pathogen is Marssonina brunnea f. sp. multigermtubi. To date, little is known about the molecular mechanism of poplar (M. brunnea) interaction. In order to identify the proteins related to disease resistance and understand its molecular basis, the clone "NL895" (P. euramericana CL"NL895"), which is highly resistant to M. brunnea f. sp. multigermtubi, was used in this study. We used two-dimensional gel electrophoresis (2-DE) and mass spectrometry (MS) to identify the proteins in poplar leaves that were differentially expressed in response to black spot disease pathogen, M. brunnea f. sp. multigermtubi. Proteins extracted from poplar leaves at 0, 12, 24, 48, and 72 h after pathogen-inoculation were separated by 2-DE, About 500 reproducible protein spots were detected, of which 40 protein spots displayed differential expression in levels and were subjected to Matrix assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) followed by database searching. According to the function, the identified proteins were sorted into five categories, that is, protein synthesis, metabolism, defense response and unclassified proteins.展开更多
Lyantria dispar larvae were fed with the leaves of Populus deltoids seedlings exposed to methyl jasmonate (MeJA) for 24 h. The growth and development of the larvae were investigated, and phenolics contents in treate...Lyantria dispar larvae were fed with the leaves of Populus deltoids seedlings exposed to methyl jasmonate (MeJA) for 24 h. The growth and development of the larvae were investigated, and phenolics contents in treated leaves including pyrocatechol, caffeic acid, coumarin, fernlic acid and benzoic acid were also surveyed by high-pressure liquid chromatography (HPLC). Results indicated that approximate digestibility, efficiency of conversion of ingested food, efficiency of conversion of digested food, and weight of the larvae were inhibited obviously, especially from the sixth day, which may result from the increase of total phenolics contents in treated leaves. This result provides strong supports for MeJA acting as the airborne signal molecule between woody plants.展开更多
Downy mildew is a serious disease in cucumber production worldwide,which is caused by Pseudoperonospora cubensis(Berk.&Curt.)Rostov.Underlying the mechanism of cucumber response to downy mildew infection is import...Downy mildew is a serious disease in cucumber production worldwide,which is caused by Pseudoperonospora cubensis(Berk.&Curt.)Rostov.Underlying the mechanism of cucumber response to downy mildew infection is important for breeding improvement and production;however,the research remains largely elusive.A comparative proteomic approach was used to reveal the differential accumulation of the proteomes from leaves of cucumber(susceptible line and resistant line)that were inoculated with P.cubensis or not by two-dimensional electrophoresis and MALDI-TOF/TOF MS.A total of 76 protein spots were successfully identified with significant changes in abundance(>2-fold,P<0.05)in downy mildew infected or not leaves for the susceptible line and resistant line.By the functional annotation,these proteins were classified into 8 groups including photosynthesis(29%),energy and metabolism(29%),cell rescue and defense(17%),and protein biosynthesis,folding and degradation(13%),unclassified(7%),nucleotide metabolism(3%),signal transduction(1%)and cellular process(1%).Among the 17 differentially expressed proteins between the resistant and susceptible cucumber line,most of the protein spots were concentrated in cell rescue and defense(4)and energy and metabolism(4).Moreover,a schematic diagram containing majority of the metabolic pathways of cucumber leaves in response to downy mildew was proposed.This network revealed the positive effect of several functional components in cucumber seedlings’resistant to downy mildew such as accumulation of energy supply and resistance-related proteins,hastened protein metabolism and photorespiratory,inhibited photosynthesis,and triggered photosystem repair and programmed cell death.Taken together,these results have advanced a further understanding of the key metabolic pathways of cucumber resistance to downy mildew and pathogen control in the proteomic level.展开更多
Investigations into the potential application of nanoparticles acting as nanofungicides in sustainable agriculture are rapidly expanding due to the high antimicrobial properties of these compounds,which do not risk in...Investigations into the potential application of nanoparticles acting as nanofungicides in sustainable agriculture are rapidly expanding due to the high antimicrobial properties of these compounds,which do not risk inducing pathogen resistance to fungicides.A detailed understanding of the impact of copper oxide nanoparticles(CuO NPs)on soil-borne phytopathogenic fungi is yet to be obtained.This study aimed to explore the in vitro antifungal activity and control efficacy of CuO NPs applied via irrigation with respect to tobacco black shank(TBS)disease caused by Phytophthora nicotianae.The results revealed that CuO NPs greatly interfered with the reproductive growth process of this fungus,repressing hyphal growth,spore germination and sporangium production.Additionally,morphological damage,intracellular ROS accumulation and increased SOD enzyme activity in hyphae were the antifungicidal mechanisms of these NPs.In pot experiments,treatment with CuO NPs at 100 mg L^(–1)significantly suppressed TBS development,compared with the effect on control plants,and the control efficacy reached 33.69%without inducing phytotoxicity.Exposure to CuO NPs significantly activated a series of defense enzymes,and resistance genes in tobacco can further explain the mechanisms by which CuO NPs suppressed fungal infection.The Cu content in both the leaves and roots of P.nicotianae-infested plants increased by 50.03 and 27.25%,respectively,after treatment with 100 mg L^(–1)CuO NPs,compared with that of healthy plants.In particular,a higher Cu content was observed in infected roots than in leaves.Therefore,this study showed the potential of CuO NPs applied as nanofungicides and as nanoinducers of fungus resistance genes for the management of TBS through inhibition of pathogen infection and stimulation of plant defenses.展开更多
During the attack of a pathogen, a variety of defense-associated proteins are released by the host plant in the apoplast to impede the perceived attack. This study utilized the mass spectrometry(LC-MS/MS) and label-fr...During the attack of a pathogen, a variety of defense-associated proteins are released by the host plant in the apoplast to impede the perceived attack. This study utilized the mass spectrometry(LC-MS/MS) and label-free quantification method to analyze the apoplastic fluid(APF) from maize stalk and identified the proteins responsive to the Fusarium verticillioides infection. We have identified 742 proteins, and among these, 119 proteins were differentially accumulated(DAPs), i.e., 35 up-regulated, 18 down-regulated, and 66 proteins were only induced by the pathogen infection. The differentially accumulated proteins were analyzed for their Gene Ontology(GO) and Kyoto Encyclopedia of Gene and Genomes(KEGG) pathway enrichment. The highly enriched Biological Process(BP) term was the L-serine biosynthesis process, whereas the most enriched Molecular Function(MF) term was the cysteine-type endopeptidase inhibitor activity. It was also found that the pathways related to the biosynthesis of amino acid, biosynthesis of secondary metabolites, protein processing in the endoplasmic reticulum, and carbohydrate metabolic pathways were significantly enriched. Moreover, 61 out of 119 differentially accumulated proteins were predicted as secretory proteins. The secretory pathways analysis showed that a greater number of proteins were secreted through the conventional secretion system compared to the unconventional secretion system. The identified secreted proteins were related to a variety of pathways in defense responses including cell redox homeostasis, cell wall modification, signal transduction, carbohydrate metabolism, binding proteins(metal ion binding, RNA binding and heme-binding), maintenance and stabilization of other proteins, indicating a complex response from the plant to the fungal infection. Our data suggested that a number of host proteins belonging to various pathways have been modulated in the apoplastic region.展开更多
The changes of malondialdehyde (MDA), H2O2, and O2^7 content, or the activities of superoxide dismutase (SOD), catalase (CAT), ascrobate peroxidase (APX), peroxidase (POD), phenylalanine ammonia lyase (PAL...The changes of malondialdehyde (MDA), H2O2, and O2^7 content, or the activities of superoxide dismutase (SOD), catalase (CAT), ascrobate peroxidase (APX), peroxidase (POD), phenylalanine ammonia lyase (PAL), and polyphenol oxidase (PPO) in pea seedlings (Pisum sativum L.) under wounding and treatment of exogenous jasmonic acid (JA) were investigated. The results showed that the activities of both phenylalanine ammonia lyase (PAL) and polyphenol oxidase (PPO) were significantly increased by wounding and application of JA. The metabolism of reaction oxidative species (ROS) was enhanced, especially O2^7 and H2O2 appeared to rapidly increase. The activities of antioxidant enzymes such as SOD, CAT, APX and POD were also increased. Treatment of JA of 1 or 10 μmol L^-1 could effectively induce plant defense response, and thus decrease the peroxidation of cell membrane lipid. However, high concentration of JA (100 μmol L^-1) resulted in unbalance of metabolism of ROS and promoted the peroxidation of cell membrane lipid. We thus suggested that JA, under the suitable concentration, could induce defense response of pea seedlings to wounding.展开更多
Animals promote their survival by avoiding rapidly approaching objects that indicate threats.It is believed that looming cues are detected by retinal ganglion cells(RGCs)that project to the superior colliculus(SC).How...Animals promote their survival by avoiding rapidly approaching objects that indicate threats.It is believed that looming cues are detected by retinal ganglion cells(RGCs)that project to the superior colliculus(SC).However,the exact type of RGC that transmits looming-related signals remains unclear.Here we identify a specific transient type of RGCs that controls mouse looming-evoked defensive response by sending axonal collaterals to the dorsal raphe nucleus(DRN)and SC.Looming signals transmitted by DRN-projecting RGCs activate DRN GABA neurons and in turn inhibit serotonin neurons.Moreover,optogenetically stimulating serotonin neurons reduces looming-evoked defensive behaviors.Thus,a dedicated population of RGCs detects rapidly approaching visual threats and their input to the DRN controls a serotonergic self-gating mechanism that regulates innate defensive responses.Our study provides new insights into how DRN and SC work in concert to extract and translate visual threats into defensive behavioral responses.展开更多
Field monitoring revealed that the infection ratio of the bacterial symbiont Cardinium in the whitefly(Bemisia tabaci MED)was relatively low in northern China.However,the role of this symbiont and the symbiont-whitefl...Field monitoring revealed that the infection ratio of the bacterial symbiont Cardinium in the whitefly(Bemisia tabaci MED)was relatively low in northern China.However,the role of this symbiont and the symbiont-whitefly-host plant interaction mechanism are poorly understood.We investigated the influence of Cardinium on the competitiveness of the host whitefly and the physiological interaction between the host plants and host whiteflies.Cardinium-infected whiteflies were displaced by uninfected whiteflies after 5 generations,which showed that Cardinium infection reduced whitefly competitiveness.The defense response genes of cotton significantly decreased under infestation by infected whiteflies compared to uninfected whiteflies.The expression of detoxification metabolism genes,especially the uridine 5ʹ-diphospho-glucuronyltransferase and P450 genes,in infected whiteflies significantly decreased.These results demonstrated that Cardinium could inhibit the defense response of the host plant and decrease the detoxification metabolism ability of the host whitefly.The reduced competitiveness of infected whiteflies may be associated with the inhibition of the whitefly detoxification metabolism by Cardinium,resulting in the reduced performance of infected whiteflies.However,Cardinium infection can suppress plant defenses,which may benefit both infected and uninfected whiteflies when they coexist.This research illustrates the symbiont–whitefly–host plant interaction mechanism and the population dynamics of the whitefly.展开更多
Parvalbumin-positive retinal ganglion cells(PV+RGCs)are an essential subset of RGCs found in various species.However,their role in transmitting visual information remains unclear.Here,we characterized PV+RGCs in the r...Parvalbumin-positive retinal ganglion cells(PV+RGCs)are an essential subset of RGCs found in various species.However,their role in transmitting visual information remains unclear.Here,we characterized PV+RGCs in the retina and explored the functions of the PV+RGC-mediated visual pathway.By applying multiple viral tracing strategies,we investigated the downstream of PV+RGCs across the whole brain.Interestingly,we found that the PV+RGCs provided direct monosynaptic input to PV+excitatory neurons in the superficial layers of the superior colliculus(SC).Ablation or suppression of SC-projecting PV+RGCs abolished or severely impaired the flight response to looming visual stimuli in mice without affecting visual acuity.Furthermore,using transcriptome expression profiling of individual cells and immunofluorescence colocalization for RGCs,we found that PV+RGCs are predominant glutamatergic neurons.Thus,our findings indicate the critical role of PV+RGCs in an innate defensive response and suggest a non-canonical subcortical visual pathway from excitatory PV+RGCs to PV+SC neurons that regulates looming visual stimuli.These results provide a potential target for intervening and treating diseases related to this circuit,such as schizophrenia and autism.展开更多
基金supported by the National Natural Science Foundation of China(31972218,31501590,and 31601615)the Program for Talents in Qingdao Agricultural University,China(6631114307)the Independent Innovation of Agricultural Sciences in Jiangsu Province,China(CX(18)3012)。
文摘A number of plant pathogenic species of Phytophthora are known to produce different classes of secretory proteins during interactions with their hosts.Although several small cysteine-rich(SCR)secretory proteins,conserved in oomycete pathogens,have been identified in Phytophthora,their specific involvement in these interactions remains unknown.In this study,an SCR effector encoded by Pn SCR82 in P.nicotianae was identified and shown to have similarities to P.cactorum phytotoxic protein,Pc F(Phytophthora cactorum Fragaria).Agroinfection with potato virus X vector,Pn SCR82,was capable of inducing plant hypersensitive cell death in Nicotiana benthamiana and Solanum lycopersicum.Real-time PCR results indicated that transiently expressed Pn SCR82 in N.benthamiana leaves activated the jasmonate,salicylic acid and ethylene signaling pathways.Transient expression of Pn SCR82 enhanced plant resisitance to P.capsici.In summary,our results demonstrated that P.nicotianae Pn SCR82 elicits defensive responses in N.benthamiana and may potentially play a significant role in future crop protection programs.
文摘Phenotypical, cytological and molecular responses of rice to the fungus Magnaporthe grisea were studied using rice cultivars and lesion mimic plants. The cultivar Katy was susceptible to several virulent M. grisea isolates, and a Sekiguchi like-lesion mimic mutant of Katy (LmmKaty) showed enhanced resistance to these isolates. Lesion mimic phenotype of LmmKaty was rapidly induced by virulent M. grisea isolates or by avirulent ones only at high levels of inoculum. Autofluorescence (a sign of an active defense response) was visible under ultraviolet light 24 h after localized inoculation in the incompatible interaction, whereas, not evident in the compatible interaction. Autofluorescence was also observed in LmmKaty 20 h after pathogen inoculation, indicating that rapid cell death is a mechanism of LmmKaty to restrict pathogen invasion. Rapid accumulations of defense related (DR) gene transcripts, phenylalanine ammonia lyase and β-glucanase, were observed beginning at 6 h and were obvious at 16 h and 24 h after inoculation in an incompatible interaction. Rapid transcript accumulations of PR-1 and chitinase had occurred by 24 h after inoculation in an incompatible interaction. Accumulations of these transcripts were delayed in the compatible interaction. These results indicate that host active defense responses occur 24 h after pathogen inoculation and that LmmKaty exhibits enhanced resistance to M. grisea. It is suggested that the autofluorescence and expression of the DR genes after heavy inoculation are important cytological and molecular markers respectively for early determination of the host response to M. grisea in the rice blast system.
基金financially supported by grants from the National Key Research and Development Program of China(2016YFD0100601)the National Natural Science Foundation of China(31701057 and 31672013)+5 种基金the Natural Science Foundation of Jiangsu Province,China(BK20170487)the Fok Ying Tung Education Foundation,China(151026)the China Postdoctoral Science Foundation(2017M620227)a project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions,China(PAPD)the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(19KJD210001)2018 Annual Key Project of Scientific Research in Yangzhou Polytechnic College,China(2018ZR07)。
文摘The soil-borne necrotrophic fungus Rhizoctonia solani is one of destructive fungi causing severe yield losses in various important crops. However, the host defense mechanisms against the invasion of this pathogen are poorly understood. In this study, we employed an i TRAQ-based quantitative proteomic approach to investigate host proteins responsive to R. solani using the resistant rice cultivar YSBR1. As a whole, we identified 319 differentially accumulated proteins(DAPs) after inoculation of rice plants with R. solani. Functional categorization analysis indicates that these DAPs cover a broad range of functions. Notably, a substantial portion of the DAPs are involved in cell redox homeostasis, carbohydrate metabolism, and phenylpropanoid biosynthesis, or belong to pathogenesis-related proteins, indicating that these processes/proteins play important roles in host defense against R. solani. Interestingly, all of the DAPs involved in photosynthesis and chlorophyll biosynthetic processes, and part of the DAPs involved in phenylpropanoid biosynthesis, show reduced accumulation after R. solani infection, suggesting that R. solani probably inhibits host photosynthetic system and phenylpropanoid biosynthesis to facilitate infection and colonization. In conclusion, our results provide both valuable resources and new insights into the molecular mechanisms underlying rice and R. solani interaction.
基金supported by Beijing Natural Science Foundation (Grant No. 5172021), China
文摘High-throughput transcriptomics technologies have been widely used to study plant transcriptional reprogramming during the process of plant defense responses, and a large quantity of gene expression data have been accumulated in public repositories. However, utilization of these data is often hampered by the lack of standard metadata annotation. In this study, we curated2444 public pathogenesis-related gene expression samples from the model plant Arabidopsis and three major crops (maize, rice, and wheat). We organized the data into a user-friendly database termed as PlaD. Currently, PlaD contains three key features. First, it provides large-scale curated data related to plant defense responses, including gene expression and gene functional annotation data.Second, it provides the visualization of condition-specific expression profiles. Third, it allows users to search co-regulated genes under the infections of various pathogens. Using PlaD, we conducted a large-scale transcriptome analysis to explore the global landscape of gene expression in the curated data. We found that only a small fraction of genes were differentially expressed under multiple conditions, which might be explained by their tendency of having more network connections and shorter network distances in gene networks. Collectively, we hope that PlaD can serve as an important and comprehensive knowledgebase to the community of plant sciences, providing insightful clues to better understand the molecular mechanisms underlying plant immune responses. PlaD is freely available at http://systbio.cau.edu.cn/plad/index.php or http://zzdlab.com/plad/index.php.
基金This work was supported by the National key R&D plan(2016YFD0101006)Yunnan Fundamental Research Projects(2019FA010).
文摘Verticillium wilt,caused by Verticillium dahliae,seriously restricts the yield and quality improvement of cotton.Previous studies have revealed the involvement of WRKY members in plant defense against V.dahliae,but the underlying mechanisms involved need to be further elucidated.Here,we demonstrated that Gossypium hirsutum WRKY DNA-binding protein 33(GhWRKY33) functions as a negative regulator in plant defense against V.dahliae.GhWRKY33 expression is induced rapidly by V.dahliae and methyl jasmonate,and overexpression of GhWRKY33 reduces plant tolerance to V.dahliae in Arabidopsis.Quantitative RT-PCR analysis revealed that expression of several JA-associated genes was significantly repressed in GhWRKY33 overexpressing transgenic plants.Yeast one-hybrid analysis revealed that GhWRKY33 may repress the transcription of both AtERF1 and GhERF2 through its binding to their promoters.Protein-protein interaction analysis suggested that GhWRKY33 interacts with G.hirsutum JASMONATE ZIM-domain protein 3(GhJAZ3).Similarly,overexpression of GhJAZ3 also decreases plant tolerance to V.dahliae.Furthermore,GhJAZ3 acts synergistically with GhWRKY33 to suppress both AtERF1 and GhERF2 expression.Our results imply that GhWRKY33 may negatively regulate plant tolerance to V.dahliae via the JA-mediated signaling pathway.
基金the Ministry of Agriculture and Rural Affairs of the People’s Republic of China(2018ZX0800917B)grant from Yunnan Provincial Science and Technology Department(202005AF150026).
文摘Plants adaptively change their cell wall composition and structure during their growth,development,and interactions with environmental stresses.Dirigent proteins(DIRs)contribute to environmental adaptations by dynamically reorganizing the cell wall and/or by generating defense compounds.A maize DIR,ZmDRR206,was previously reported to play a dominant role in regulation of storage nutrient accumulation in endosperm during maize kernel development.Here we show that ZmDRR206 mediates maize seedling growth and disease resistance by coordinately regulating biosynthesis of cell wall components for cell-wall integrity(CWI)maintenance.Expression of ZmDRR206 was induced in maize seedlings upon pathogen infection.ZmDRR206 overexpression in maize resulted in reduced seedling growth and photosynthetic activity but increased disease resistance and drought tolerance,revealing a tradeoff between growth and defense.Consistently,ZmDRR206 overexpression reduced the contents of primary metabolites and down-regulated genes involved in photosynthesis,while increasing the contents of major cell wall components,defense phytohormones,and defense metabolites,and up-regulated genes involved in defense and cell-wall biosynthesis in seedlings.ZmDRR206-overexpressing seedlings were resistant to cell-wall stress imposed by isoxaben,and ZmDRR206 physically interacted with ZmCesA10,which is a cellulose synthase unit.Our findings suggest a mechanism by which ZmDRR206 coordinately regulates biosynthesis of cell-wall components for CWI maintenance during maize seedling growth,and might be exploited for breeding strong disease resistance in maize.
文摘Due to the hidden nature of roots in the soils, it is more challenging to investigate their resistance traits and defense responses as compared to those of the aerial organs. At the same time, it is self-evident that root health is fundamental to a plant’s entire life and productivity. It is also easily conceivable that root function, physiology, morphology, and architecture are constantly impacted by the complex soil environment including both biotic and abiotic factors. This report summarizes and updates the challenges and progress in evaluating resistance responses of apple root to infection from a necrotrophic oomycete pathogen, Pythium ultimum. Several obstacles impede the progress of investigating apple root resistance traits including the difficulties of direct and real-time evaluation and the lack of a continuous supply of apple plants for repeated infection assays. Systematic and detailed analyses were made possible by implementing a micropropagation procedure for continuously generating uniform apple plants for repeated infection assays. As a result, an elite panel of apple rootstock germplasm with distinct resistance levels was identified. These apple rootstock genotypes with well-defined resistance levels are the much-needed plant materials for subsequent genomics and transgenics analyses to define the functional roles of specific candidate genes. Careful microscopic examination revealed contrasting necrosis progression patterns between resistant and susceptible genotypes, which shed light on the potential mechanisms underlying resistance traits. Our continuing research will provide a clearer view regarding the genetic elements regulating resistance traits in apple roots to P. ultimum infection.
基金financially supported by the National Natural Science Foundation of China(Grant No.32202463)China Agriculture Research System(Grant No.CARS-27)the Agricultural Science and Technology Innovation Program(Grant No.CAAS-ASTIP-2021-RIP-02)。
文摘Apple leaf spot,caused by the Alternaria alternata apple pathotype(AAAP),is an important fungal disease of apple.To understand the molecular basis of resistance and pathogenesis in apple leaf spot,the transcriptomes of two apple cultivars‘Hanfu'(HF)(resistant)and‘Golden Delicious'(GD)(susceptible)were analyzed at 0,6,18,24 and 48 h after AAAP inoculation by RNA-Seq.At each time point,a large number of significantly differentially expressed genes(DEGs)were screened between AAAP-inoculated and uninoculated apple leaves.Analysis of the common DEGs at four time points revealed significant differences in the resistance of‘HF'and‘GD'apple to AAAP infection.RLP,RNL,and JA signal-related genes were upregulated in both cultivars to restrict AAAP development.However,genes encoding CNLs,TNLs,WRKYs,and AP2s were only activated in‘HF'as part of the resistance response,of which,some play major roles in the regulation of ET and SA signal transduction.Further analysis showed that many DEGs with opposite expression trends in the two hosts may play important regulatory roles in response to AAAP infection.Transient expression of one such gene MdERF110 in‘GD'apple leaves improved AAAP resistance.Collectively,this study highlights the reasons for differential resistance to AAAP infection between‘HF'and‘GD'apples which can theoretically assist the molecular breeding of disease-resistant apple crops.
基金supported by the National Natural Science Foundation of China(Grant No.31771836)the National Key Research and Development Program of China(Grant No.2018YFD0201003).
文摘With the development of tourism at home and abroad,Rapeseed(Brassica napus)has become an important ornamental plant.However,its ornamental value at the inflorescence stage is greatly reduced by Sclerotinia sclerotiorum.Identification of important genes in the defense responses is critical for molecular breeding,which is an important strategy for controlling the disease.In this study,we isolated a B.napus WRKY transcription factor gene,BnaWRKY75.BnaWRKY75 was found to encode a nucleus-localized protein and exhibited relatively high expression in the stems.Arabidopsis thaliana transgenic plants expressing BnaWRKY75 showed enhanced resistance to S.sclerotiorum,and both ProBnaWRKY75:GUS and gene expression analyses showed that BnaWRKY75 was highly responsive to S.sclerotiorum infection,indicating the involvement of BnaWRKY75 in response to this infection.Furthermore,overexpression(OE)of BnaWRKY75 in B.napus significantly enhanced the resistance to S.sclerotiorum,whereas the resistance was reduced in RNAi transgenic B.napus plants.Moreover,the BnaWRKY75-OE B.napus plants exhibited constitutive activation of salicylic acid-,jasmonic acid-,and ethylene-mediated defense responses and the inhibition of both H_(2)O_(2)and O_(2)·^(-)accumulation in response to this pathogen.By contrast,BnaWRKY75-RNAi plants showed a reverse pattern,suggesting that BnaWRKY75 is involved in hormonal signaling pathways and in the control of reactive oxygen species accumulation.In conclusion,these data indicate that BnaWRKY75,a regulator of multiple defense responses,positively regulates resistance against S.sclerotiorum,which may guide the improvement of resistance in rapeseed.
基金the Beijing Leafy Vegetables Innovation Team of Modern Agro-industry Technology Research System,China(BAIC07)the Beijing Natural Science Foundation,China(5051002)。
文摘Chinese cabbage(Brassica rapa subsp.pekinensis)suffers from soft rot disease caused by Pectobacterium carotovorum(Pc).To uncover the mechanisms underlying the defense response of Chinese cabbage to Pc,we constructed a suppression subtractive hybridization(SSH)library from Pc-infected cabbage and obtained 1919 non-redundant expressed sequence tags(ESTs),which were used for cDNA microarray.We detected 800 differentially expressed genes(DEGs)in cabbage at different time points post-Pc inoculation,which were further confirmed by quantitative real-time PCR.One quarter of these DEGs were involved in the biotic stress pathways visualized by MapMan.Among them,8,8,1,3,and 2 DEGs were related to jasmonic acid(JA),ethylene(ET),JA+ET,auxin,and abscisic acid(ABA)signaling pathways,respectively,while no DEG was detected for salicylic acid(SA)signaling.Assessment of phytohormone production in the Pc-infected leaves showed that JA and ET production was increased,while SA production was decreased.Treatment with JA,methyl jasmonate(MeJA),the ET precursor 1-aminocyclopropane-1-carboxylate(ACC),or combinations thereof,reduced the disease severity,and the JA and JA+ACC treatments were superior and performed equally well.Our findings suggest that JA and ET may act synergistically against Pc infection in Chinese cabbage,and JA-mediated signaling might be the most significant.
基金supported by the grants from the National Key R&D Program of China (2017YFD0100901-4 and 2016YFC0502604)the National Natural Science Foundation of China (31660390)+5 种基金the Major Special Project of Science and Technology Program in Guizhou, China (2017-5411-06 and 2017-5788)the Construction Project of State Engineering Technology Institute for Karst Desertification Control, China (2012FU125X13)the Innovation Talents Team Construction of Science and Technology in Guizhou, China (2016-5624)the Major Research Project of Innovation Group in Guizhou, China (2016-023)the Graduate Innovation Fund of Guizhou University, China (2017025)the Science and Technology Project in Guizhou, China (2019-4246)
文摘Triticum aestivum L. cv. Guizi 1(GZ1) is a drought-tolerant local purple wheat cultivar. It is not clear how purple wheat resists drought stress, but it could be related to anthocyanin biosynthesis. In this study, transcriptome data from droughttreated samples and controls were compared. Drought slightly reduced the anthocyanin, protein and starch contents of GZ1 grains and significantly reduced the grain weight. Under drought stress, 16 682 transcripts were reduced, 27 766 differentially expressed genes(DEGs) were identified, and 379 DEGs, including DREBs, were related to defense response. The defense-response genes included response to water deprivation, reactive oxygen, bacteria, fungi, etc. Most of the structural and regulatory genes in anthocyanin biosynthesis were downregulated, with only Ta DFR, Ta OMT, Ta5,3GT, and Ta MYB-4 B1 being upregulated. Ta CHS, Ta F3H, TaCHI, Ta4CL, and TaF3’H are involved in responses to UV, hormones, and stimulus. Ta CHS-2D1, Ta DFR-2D2, Ta DFR-7D, TaOMT-5A, Ta5,3 GT-1B1, Ta5,3GT-3A, and Ta5,3GT-7B1 connect anthocyanin biosynthesis with other pathways, and their interacting proteins are involved in primary metabolism, genetic regulation, growth and development, and defense responses. There is further speculation about the defense-responsive network in purple wheat. The results indicated that biotic and abiotic stress-responsive genes were stimulated to resist drought stress in purple wheat GZ1, and anthocyanin biosynthesis also participated in the drought defense response through several structural genes.
基金This work was supported by the National Natural Science Foundation of China (No. 30230300).
文摘Black spot disease in poplar is a disease of the leaf caused by fungus. The major pathogen is Marssonina brunnea f. sp. multigermtubi. To date, little is known about the molecular mechanism of poplar (M. brunnea) interaction. In order to identify the proteins related to disease resistance and understand its molecular basis, the clone "NL895" (P. euramericana CL"NL895"), which is highly resistant to M. brunnea f. sp. multigermtubi, was used in this study. We used two-dimensional gel electrophoresis (2-DE) and mass spectrometry (MS) to identify the proteins in poplar leaves that were differentially expressed in response to black spot disease pathogen, M. brunnea f. sp. multigermtubi. Proteins extracted from poplar leaves at 0, 12, 24, 48, and 72 h after pathogen-inoculation were separated by 2-DE, About 500 reproducible protein spots were detected, of which 40 protein spots displayed differential expression in levels and were subjected to Matrix assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) followed by database searching. According to the function, the identified proteins were sorted into five categories, that is, protein synthesis, metabolism, defense response and unclassified proteins.
基金This research was supported by National Natural Science Foundation of China (No.30170764)
文摘Lyantria dispar larvae were fed with the leaves of Populus deltoids seedlings exposed to methyl jasmonate (MeJA) for 24 h. The growth and development of the larvae were investigated, and phenolics contents in treated leaves including pyrocatechol, caffeic acid, coumarin, fernlic acid and benzoic acid were also surveyed by high-pressure liquid chromatography (HPLC). Results indicated that approximate digestibility, efficiency of conversion of ingested food, efficiency of conversion of digested food, and weight of the larvae were inhibited obviously, especially from the sixth day, which may result from the increase of total phenolics contents in treated leaves. This result provides strong supports for MeJA acting as the airborne signal molecule between woody plants.
基金This work was supported by the Hebei Province Scientific and Technological Support Program(Grant No.16226308D-4)Hebei Vegetable Innovation Projects of Modern Agricultural Industry Technology System(Grant No.HBCT2018030209)Hebei Province High Education Science and Technology Research Project(Grant No.BJ2018002).
文摘Downy mildew is a serious disease in cucumber production worldwide,which is caused by Pseudoperonospora cubensis(Berk.&Curt.)Rostov.Underlying the mechanism of cucumber response to downy mildew infection is important for breeding improvement and production;however,the research remains largely elusive.A comparative proteomic approach was used to reveal the differential accumulation of the proteomes from leaves of cucumber(susceptible line and resistant line)that were inoculated with P.cubensis or not by two-dimensional electrophoresis and MALDI-TOF/TOF MS.A total of 76 protein spots were successfully identified with significant changes in abundance(>2-fold,P<0.05)in downy mildew infected or not leaves for the susceptible line and resistant line.By the functional annotation,these proteins were classified into 8 groups including photosynthesis(29%),energy and metabolism(29%),cell rescue and defense(17%),and protein biosynthesis,folding and degradation(13%),unclassified(7%),nucleotide metabolism(3%),signal transduction(1%)and cellular process(1%).Among the 17 differentially expressed proteins between the resistant and susceptible cucumber line,most of the protein spots were concentrated in cell rescue and defense(4)and energy and metabolism(4).Moreover,a schematic diagram containing majority of the metabolic pathways of cucumber leaves in response to downy mildew was proposed.This network revealed the positive effect of several functional components in cucumber seedlings’resistant to downy mildew such as accumulation of energy supply and resistance-related proteins,hastened protein metabolism and photorespiratory,inhibited photosynthesis,and triggered photosystem repair and programmed cell death.Taken together,these results have advanced a further understanding of the key metabolic pathways of cucumber resistance to downy mildew and pathogen control in the proteomic level.
基金financial support by the National Natural Science Foundation of China(32001934)the Key Science and Technology Project of Sichuan Tobacco Company,China(SCYC202114)。
文摘Investigations into the potential application of nanoparticles acting as nanofungicides in sustainable agriculture are rapidly expanding due to the high antimicrobial properties of these compounds,which do not risk inducing pathogen resistance to fungicides.A detailed understanding of the impact of copper oxide nanoparticles(CuO NPs)on soil-borne phytopathogenic fungi is yet to be obtained.This study aimed to explore the in vitro antifungal activity and control efficacy of CuO NPs applied via irrigation with respect to tobacco black shank(TBS)disease caused by Phytophthora nicotianae.The results revealed that CuO NPs greatly interfered with the reproductive growth process of this fungus,repressing hyphal growth,spore germination and sporangium production.Additionally,morphological damage,intracellular ROS accumulation and increased SOD enzyme activity in hyphae were the antifungicidal mechanisms of these NPs.In pot experiments,treatment with CuO NPs at 100 mg L^(–1)significantly suppressed TBS development,compared with the effect on control plants,and the control efficacy reached 33.69%without inducing phytotoxicity.Exposure to CuO NPs significantly activated a series of defense enzymes,and resistance genes in tobacco can further explain the mechanisms by which CuO NPs suppressed fungal infection.The Cu content in both the leaves and roots of P.nicotianae-infested plants increased by 50.03 and 27.25%,respectively,after treatment with 100 mg L^(–1)CuO NPs,compared with that of healthy plants.In particular,a higher Cu content was observed in infected roots than in leaves.Therefore,this study showed the potential of CuO NPs applied as nanofungicides and as nanoinducers of fungus resistance genes for the management of TBS through inhibition of pathogen infection and stimulation of plant defenses.
基金partially supported by the National Key Research and Development Program of China(2017YFC1600903 and 2016YFD040015)the National Natural Science Foundation of China(32072377)+2 种基金the Beijing Natural Science Foundation,China(6192023)the Agricultural Science and Technology Innovation Program of China(CAAS-ASTIP-2020-IFST-03)the scholarship grant from the China Scholarship Council(CSC)(2017GXZ022555)。
文摘During the attack of a pathogen, a variety of defense-associated proteins are released by the host plant in the apoplast to impede the perceived attack. This study utilized the mass spectrometry(LC-MS/MS) and label-free quantification method to analyze the apoplastic fluid(APF) from maize stalk and identified the proteins responsive to the Fusarium verticillioides infection. We have identified 742 proteins, and among these, 119 proteins were differentially accumulated(DAPs), i.e., 35 up-regulated, 18 down-regulated, and 66 proteins were only induced by the pathogen infection. The differentially accumulated proteins were analyzed for their Gene Ontology(GO) and Kyoto Encyclopedia of Gene and Genomes(KEGG) pathway enrichment. The highly enriched Biological Process(BP) term was the L-serine biosynthesis process, whereas the most enriched Molecular Function(MF) term was the cysteine-type endopeptidase inhibitor activity. It was also found that the pathways related to the biosynthesis of amino acid, biosynthesis of secondary metabolites, protein processing in the endoplasmic reticulum, and carbohydrate metabolic pathways were significantly enriched. Moreover, 61 out of 119 differentially accumulated proteins were predicted as secretory proteins. The secretory pathways analysis showed that a greater number of proteins were secreted through the conventional secretion system compared to the unconventional secretion system. The identified secreted proteins were related to a variety of pathways in defense responses including cell redox homeostasis, cell wall modification, signal transduction, carbohydrate metabolism, binding proteins(metal ion binding, RNA binding and heme-binding), maintenance and stabilization of other proteins, indicating a complex response from the plant to the fungal infection. Our data suggested that a number of host proteins belonging to various pathways have been modulated in the apoplastic region.
基金the National Natural Sci-ence Foundation of China(30270918) the National High Technology Research and Development Programof China(863 Program2003AA241170).
文摘The changes of malondialdehyde (MDA), H2O2, and O2^7 content, or the activities of superoxide dismutase (SOD), catalase (CAT), ascrobate peroxidase (APX), peroxidase (POD), phenylalanine ammonia lyase (PAL), and polyphenol oxidase (PPO) in pea seedlings (Pisum sativum L.) under wounding and treatment of exogenous jasmonic acid (JA) were investigated. The results showed that the activities of both phenylalanine ammonia lyase (PAL) and polyphenol oxidase (PPO) were significantly increased by wounding and application of JA. The metabolism of reaction oxidative species (ROS) was enhanced, especially O2^7 and H2O2 appeared to rapidly increase. The activities of antioxidant enzymes such as SOD, CAT, APX and POD were also increased. Treatment of JA of 1 or 10 μmol L^-1 could effectively induce plant defense response, and thus decrease the peroxidation of cell membrane lipid. However, high concentration of JA (100 μmol L^-1) resulted in unbalance of metabolism of ROS and promoted the peroxidation of cell membrane lipid. We thus suggested that JA, under the suitable concentration, could induce defense response of pea seedlings to wounding.
文摘Animals promote their survival by avoiding rapidly approaching objects that indicate threats.It is believed that looming cues are detected by retinal ganglion cells(RGCs)that project to the superior colliculus(SC).However,the exact type of RGC that transmits looming-related signals remains unclear.Here we identify a specific transient type of RGCs that controls mouse looming-evoked defensive response by sending axonal collaterals to the dorsal raphe nucleus(DRN)and SC.Looming signals transmitted by DRN-projecting RGCs activate DRN GABA neurons and in turn inhibit serotonin neurons.Moreover,optogenetically stimulating serotonin neurons reduces looming-evoked defensive behaviors.Thus,a dedicated population of RGCs detects rapidly approaching visual threats and their input to the DRN controls a serotonergic self-gating mechanism that regulates innate defensive responses.Our study provides new insights into how DRN and SC work in concert to extract and translate visual threats into defensive behavioral responses.
基金supported by the National Natural Science Foundation of China(31872030,31572064)the Taishan Scholar Foundation of Shandong Province(tsqn20161040)the First-class Grassland Science Discipline Program in Shandong Province,China.
文摘Field monitoring revealed that the infection ratio of the bacterial symbiont Cardinium in the whitefly(Bemisia tabaci MED)was relatively low in northern China.However,the role of this symbiont and the symbiont-whitefly-host plant interaction mechanism are poorly understood.We investigated the influence of Cardinium on the competitiveness of the host whitefly and the physiological interaction between the host plants and host whiteflies.Cardinium-infected whiteflies were displaced by uninfected whiteflies after 5 generations,which showed that Cardinium infection reduced whitefly competitiveness.The defense response genes of cotton significantly decreased under infestation by infected whiteflies compared to uninfected whiteflies.The expression of detoxification metabolism genes,especially the uridine 5ʹ-diphospho-glucuronyltransferase and P450 genes,in infected whiteflies significantly decreased.These results demonstrated that Cardinium could inhibit the defense response of the host plant and decrease the detoxification metabolism ability of the host whitefly.The reduced competitiveness of infected whiteflies may be associated with the inhibition of the whitefly detoxification metabolism by Cardinium,resulting in the reduced performance of infected whiteflies.However,Cardinium infection can suppress plant defenses,which may benefit both infected and uninfected whiteflies when they coexist.This research illustrates the symbiont–whitefly–host plant interaction mechanism and the population dynamics of the whitefly.
基金supported by grants from the National Key R&D Program of China(2017YFE0103400)the National Nature Science Foundation of China(81470628).
文摘Parvalbumin-positive retinal ganglion cells(PV+RGCs)are an essential subset of RGCs found in various species.However,their role in transmitting visual information remains unclear.Here,we characterized PV+RGCs in the retina and explored the functions of the PV+RGC-mediated visual pathway.By applying multiple viral tracing strategies,we investigated the downstream of PV+RGCs across the whole brain.Interestingly,we found that the PV+RGCs provided direct monosynaptic input to PV+excitatory neurons in the superficial layers of the superior colliculus(SC).Ablation or suppression of SC-projecting PV+RGCs abolished or severely impaired the flight response to looming visual stimuli in mice without affecting visual acuity.Furthermore,using transcriptome expression profiling of individual cells and immunofluorescence colocalization for RGCs,we found that PV+RGCs are predominant glutamatergic neurons.Thus,our findings indicate the critical role of PV+RGCs in an innate defensive response and suggest a non-canonical subcortical visual pathway from excitatory PV+RGCs to PV+SC neurons that regulates looming visual stimuli.These results provide a potential target for intervening and treating diseases related to this circuit,such as schizophrenia and autism.