Basal defense is enhanced in a wheat cultivar resistant to Fusarium head blight

Fusarium head blight(FHB),mainly caused by the fungal pathogen Fusarium graminearum,is one of the most destructive wheat diseases.Besides directly affecting the yield,the mycotoxin residing in the kernel greatly threatens the health of humans and livestock.Xinong 979(XN979)is a widely cultivated wheat elite with high yield and FHB resistance.However,its resistance mechanism remains unclear.In this study,we studied the expression of genes involved in plant defense in XN979 by comparative transcriptomics.We found that the FHB resistance in XN979 consists of two lines of defense.The first line of defense,which is constitutive,is knitted via the enhanced basal expression of lignin and jasmonic acid(JA)biosynthesis genes.The second line of defense,which is induced upon F.graminearum infection,is contributed by the limited suppression of photosynthesis and the struggle of biotic stress-responding genes.Meanwhile,the effective defense in XN979 leads to an inhibition of fungal gene expression,especially in the early infection stage.The formation of the FHB resistance in XN979 may coincide with the breeding strategies,such as selecting high grain yield and lodging resistance traits.This study will facilitate our understanding of wheat-F.graminearum interaction and is insightful for breeding FHB-resistant wheat.

A novel pathogen Fusarium cuneirostrum causing common bean(Phaseolus vulgaris)root rot in China

Several fungal pathogens cause root rot of common bean,among which Fusarium spp.are the most common pathogens causing Fusarium root rot(FRR)worldwide.FRR has been becoming an increasingly severe disease of common bean in China,but the species of Fusarium spp.have remained unclear.Thus,this study was performed to identify the pathogen causing common bean root rot in Liangcheng County,Inner Mongolia,China.Nineteen Fusarium-like isolates were obtained after pathogen isolation and purification.The pathogenicity test indicated that eight isolates caused severe disease symptoms on common bean,while 11 other isolates were not pathogenic.The eight pathogenic isolates,FCL1–FCL8,were identified as Fusarium cuneirostrum by morphological characterization and phylogenetic analysis using partial sequences of EF-1α,ITS,28S,and IGS regions.Host range test showed that the representative F.cuneirostrum isolate FCL3 was also pathogenic to mung bean,while not pathogenic to adzuki bean,chickpea,cowpea,faba bean,pea,and soybean.Moreover,50 common bean and 50 mung bean cultivars were screened for resistance to FRR,and seven highly resistant or resistant cultivars of common bean were identified,while no resistant cultivars of mung bean were screened.This study revealed that F.cuneirostrum was one of common bean FRR pathogens in Inner Mongolia and it could induce mung bean root rot as well.To our knowledge,this is the first report of F.cuneirostrum causing FRR of common bean in China.

5-Aminolevulinic acid against strawberry Fusarium wilt:Bidirectional regulation of biocontrol agents and pathogens

Strawberry Fusarium wilt (SFW) is a systematic soil-borne disease caused by Fusarium oxysporum f.sp.fragaria (Fof),which infects the vascular bundles,blocking water and nutrient transport from roots to the aboveground.It is a severe pathogen which spreads rapidly and destroys strawberry production.Finding a way to control this disease is of great scientific value and practical importance.In this study,three fungi were isolated from the vascular tissues of sick strawberries in the field.After DNA sequencing,they were identified as Fof,Aspergillus fumigatus and Trichoderma harzianum,respectively,among which the first two are pathogens and the third is a probiotic.All fungi were controlled by thiophanate-methyl (TM),a commercial fungicide.On PDA medium,20 mg·L^(-1)5-aminolevulinic acid (ALA),a natural non-protein amino acid,promoted T.harzianum proliferation,but inhibited Fof and A.fumigatus.In confrontation test,the growth of Fof or A.fumigatus was inhibited by T.harzianum and exogenous ALA promoted T.harzianum growth but significantly inhibited the pathogen growth.When three species of fungi were separately or combinedly inoculated on healthy strawberry plants,T.harzianum promoted plant growth and development while Fof or A.fumigatus caused growth retardation,where Fof directly caused leaf yellowing and plant wilting.When the plants inoculated with different fungus were treated with ALA,the results turned out that ALA alleviated SFW symptoms by bidirectionally promoting T.harzianum proliferation and inhibiting Fof and A.fumigatus.Thus,ALA might be used in comprehensively controlling SFW in strawberry industry.

四种杀菌剂及复配组合测定亚洲镰刀菌(Fusarium asiaticum)的毒力

为了筛选防治小麦赤霉病的有效杀菌剂及其复配制剂。通过菌丝生长速率法测定咪鲜胺、甲基硫菌灵、丙硫菌唑和戊唑醇4种杀菌剂以及咪鲜胺与丙硫菌唑复配剂对小麦赤霉病菌亚洲镰刀菌的室内毒力。结果表明,4种杀菌剂对亚洲镰刀菌均有明显的防治作用,其中,咪鲜胺对亚洲镰刀菌菌丝生长抑制效果最为明显,EC_(50)仅为0.285 9μg/mL;其次是丙硫菌唑,EC_(50)为0.348 1μg/mL;甲基硫菌灵和戊唑醇的EC_(50)分别为0.947 7、1.260 9μg/mL。复配剂咪鲜胺∶丙硫菌唑(1∶1、3∶1,V/V)具有增效作用,增效系数(SR)在1.719 1~3.069 4,其中以咪鲜胺∶丙硫菌唑(1∶1,V/V)的增效作用最好,其SR为3.069 4;其他不同组合复配剂均表现为相加作用,其SR为1.075 5~1.367 0。

WRKY11 up-regulated dirigent expression to enhance lignin/lignans accumulation in Lilium regale Wilson during response to Fusarium wilt

Lilium are highly economically valuable ornamental plants that are susceptible to Fusarium wilt caused by Fusarium oxysporum.Lilium regale Wilson,a wild lily native to China,is highly resistant to F.oxysporum.In this study,a WRKY transcription factor,WRKY11,was isolated from L.regale,and its function during the interaction between L.regale and F.oxysporum was characterized.The ectopic expression of LrWRKY11 in tobacco increased the resistance to F oxysporum,moreover,the transcriptome sequencing and UHPLC-MS/MS analysis indicated that the methyl salicylate and methyl jasmonate levels rose in LrWRKY11 transgenic tobacco,meanwhile,the expression of lignin/lignans biosynthesis-related genes including a dirigent(DiR)was up-regulated.The lignin/lignans contents in LrWRKY11-transgenic tobacco also significantly increased compared with the wild-type tobacco.In addition,the resistance of L.regale scales in which LrWRKY11 expression was silenced by RNAi evidently decreased,and additionally,the expression of lignin/lignans biosynthesis-related genes including LrDIR1 was significantly suppressed.Therefore,LrDIR1 and its promoter(PLrDIR1)sequence containing the W-box element were isolated from L.regale.The interaction assay indicated that LrWRKY11 specifically bound to the W-box element in PLrDIR1 and activated LrDIR1 expression.Additionally,β-glucuronidase activity in the transgenic tobacco co-expressing LrWRKY11/PLrDIR1-β-glucuronidase was higher than that in transgenic tobacco expressing PLrDIR1-β-glucuronidase alone.Furthermore,the ectopic expression of LrDIR1 in tobacco enhanced the resistance to F.oxysporum and increased the lignin/lignans accumulation.In brief,this study revealed that LrWRKY11 positively regulated L.regale resistance to F.oxysporum through interaction with salicylic acid/jasmonic acid signaling pathways and modulating LrDIR1 expression to accumulate lignin/lignans.

A potential hyphal fusion protein complex with an important role in development and virulence interacts with autophagy-related proteins in Fusarium pseudograminearum

Hyphal fusion(anastomosis)is a common process serving many important functions at various developmental stages in the life cycle of ascomycetous fungi.However,the biological roles and molecular mechanisms in plant pathogenic fungi were widely unknown.In this study,a hyphal fusion protein FpHam-2 was screened from a T-DNA insertion mutant library of Fusarium pseudograminearum,and FpHam-2 interacts with another 2 hyphal fusion protein homologues FpHam-3 and FpHam-4.Each of these 3 genes deletion mutant revealed in similar defective phenotypes compared with the WT and complemented strains,including reduction in growth rate,defects in hyphal fusion and conidiation,more sensitive for cell membrane,cell wall and oxidative stress responses,and decreased in virulence.The yeast two-hybrid assay was used to identify that FpHam-2 interacts with 3 autophagy-related proteins,including FpAtg3,FpAtg28 and FpAtg33.Furthermore,FpHam-2-deletion mutant showed decreased accumulation of autophagic bodies in hypha.In conclusion,FpHam-2,FpHam-3 and FpHam-4 have an essential role for hyphal fusion and regulating the growth,conidiation and virulence in F.pseudograminearum.

Identification and characterization of FpRco1 in regulating vegetative growth and pathogenicity based on T-DNA insertion in Fusarium pseudograminearum

Fusarium pseudograminearum is a devastating pathogen that causes Fusarium crown rot(FCR)in wheat and poses a significant threat to wheat production in terms of grain yield and quality.However,the mechanism by which F.pseudograminearum infects wheat remains unclear.In this study,we aimed to elucidate these mechanisms by constructing a T-DNA insertion mutant library for the highly virulent strain WZ-8A of F.pseudograminearum.By screening this mutant library,we identified nine independent mutants that displayed impaired pathogenesis in barley leaves.Among these mutants,one possessed a disruption in the gene FpRCO1 that is an ortholog of Saccharomyces cerevisiae RCO1,encoding essential component of the Rpd3S histone deacetylase complex in F.pseudograminearum.To further investigate the role of FpRCO1 in F.pseudograminearum,we employed a split-marker approach to knock out FpRCO1 in F.pseudograminearum WZ-8A.FpRCO1 deletion mutants exhibit reduced vegetative growth,conidium production,and virulence in wheat coleoptiles and barley leaves,whereas the complementary strain restores these phenotypes.Moreover,under stress conditions,the FpRCO1 deletion mutants exhibited increased sensitivity to NaCl,sorbitol,and SDS,but possessed reduced sensitivity to H_(2)O_(2)compared to these characteristics in the wild-type strain.RNA-seq analysis revealed that deletion of FpRCO1 affected gene expression(particularly the downregulation of TRI gene expression),thus resulting in significantly reduced deoxynivalenol(DON)production.In summary,our findings highlight the pivotal role of FpRCO1 in regulating vegetative growth and development,asexual reproduction,DON production,and pathogenicity of F.pseudograminearum.This study provides valuable insights into the molecular mechanisms underlying F.pseudograminearum infection in wheat and may pave the way for the development of novel strategies to combat this devastating disease.

Effects of Nitrogen-Regulating Gene AreA on Growth,Pathogenicity,and Fumonisin Synthesis of Fusarium proliferatum

Rice spikelet rot disease not only threatens rice yields but also poses risks to humans and animals due to the production of the category 2B carcinogen fumonisins by the pathogen Fusarium proliferatum.Nitrogen(N)metabolism is known to have a significant influence on fungal growth and the synthesis of secondary metabolites.AreA is a global N regulatory gene belonging to the GATA transcription factor family.In this study,we observed that theΔAreA mutant exhibited a notable reduction in growth rate and conidium production.Pathogenicity experiments revealed thatΔAreA had almost lost its ability to infect rice spikelets.

Silencing of early auxin responsive genes MdGH3-2/12 reduces the resistance to Fusarium solani in apple

Apple replant disease(ARD)has led to severe yield and quality reduction in the apple industry.Fusarium solani(F.solani)has been identified as one of the main microbial pathogens responsible for ARD.Auxin(indole-3-acetic acid,IAA),an endogenous hormone in plants,is involved in almost all plant growth and development processes and plays a role in plant immunity against pathogens.Gretchen Hagen3(GH3)is one of the early/primary auxin response genes.The aim of this study was to evaluate the function of MdGH3-2 and MdGH3-12 in the defense response of F.solani by treating MdGH3-2/12 RNAi plants with F.solani.The results show that under F.solani infection,RNAi of MdGH3-2/12 inhibited plant biomass accumulation and exacerbated root damage.After inoculation with F.solani,MdGH3-2/12 RNAi inhibited the biosynthesis of acid-amido synthetase.This led to the inhibition of free IAA combining with amino acids,resulting in excessive free IAA accumulation.This excessive free IAA altered plant tissue structure,accelerated fungal hyphal invasion,reduced the activity of antioxidant enzymes(SOD,POD and CAT),increased the reactive oxygen species(ROS)level,and reduced total chlorophyll content and photosynthetic ability,while regulating the expression of PR-related genes including PR1,PR4,PR5 and PR8.It also changed the contents of plant hormones and amino acids,and ultimately reduced the resistance to F.solani.In conclusion,these results demonstrate that MdGH3-2 and MdGH3-12 play an important role in apple tolerance to F.solani and ARD.

Biochar alleviates apple replant disease by reducing the growth of Fusarium oxysporum and regulating microbial communities

Apple replant disease(ARD)negatively affects plant growth and reduces yields in replanted orchards.In this study,biochar was applied to apple replant soil with Fusarium oxysporum.Our aim was to investigate whether biochar could promote plant growth and alleviate apple replant disease by reducing the growth of harmful soil microorganisms,changing soil microbial community structure and improving the soil environment.This experiment included five treatments:apple replant soil(CK),methyl bromide fumigation apple replant soil(FM),replant soil with biochar addition(2%),replant soil with F.oxysporum spore solution(8×10^(7)spores·mL^(-1)),and replant soil with biochar and F.oxysporum spore solution addition.Seedling biomass,the activity of antioxidant enzymes in the leaves and roots,and soil environmental variables were measured.Microbial community composition and community structure were analyzed using 16SrDNA and ITS2 gene sequencing.Biochar significantly reduced the abundance of F.oxysporum and increased soil microbial diversity and richness.Biochar also increased the soil enzyme activities(urease,invertase,neutral phosphatase,and catalase),the biomass(plant height,fresh weight,dry weight)and the activity of antioxidant enzymes(superoxide dismutase,peroxidase,and catalase).The root indexes of apple seedlings was also increased in replant soil by biochar.In sum,biochar promoted the growth of plants,improved the replant soil environment,and alleviated apple replant disease.

Reactions of Oil Palm (Elaeis guineensis Jacq) Progenies to Fusarium Wilt Disease Caused by Fusarium oxysporum f.sp. Elaeidis under Natural Infection

The oil palm (Elaeisguineensis Jacq) is used worldwide in commercial agriculture for the production of palm oil, palm kernel oil and palm wine. It produces more oil per plant than any other oil-producing crop in the world. Production is constrained by several factors among which pests/diseases are of utmost importance. Vascular wilt (VW) caused by Fusarium oxysporum is the most devastating disease infecting this crop. Its soil-borne ecology has made the use of fungicides to manage this disease too expensive and inpragmatic. There is need for concerted research in the breeding and selection of wilt-tolerant progenies as an essential step in the management of Fusarium wilt disease. The study aims to assess the incidence and severity of vascular wilt among tested oil palm progenies, to evaluate the reduction in yield caused by the disease in the susceptible progenies and to identify the wilt-tolerant, high-yielding progenies. The study was carried out at Pamol Plantations Limited (PPL) in Ndian Estate (Ndian Division), in the Southwest Region of Cameroon. Three field trials were evaluated for tolerance/susceptibility to Fusarium wilt. Each trial consisted of 15 oil palm progenies replicated 4 times. Each progeny had 25 oil palm stands in each replicate. Hence, a total of 1500 oil palm stands were assessed. The experimental design was a randomized complete block (RCB) with trial codes: Trial 2001/1, planted in 2001;Trial 2001/2, planted in 2002;Trial 2001/3, planted in 2003. Each trail had an area of 12 ha, with a plant density of 143 palms·ha−1. Wilt incidence, severity, index, and yield were evaluated on 45 progenies from the 3 trails after identifying Fusarium oxysporum from oil palm plant part. Data was subjected to analysis of variance, Fischer’s least significant difference test (LSD) for mean separation. Identification of Fusarium was based on descriptive analysis. Incidence of VW in the 3 trials ranged from 1% - 39%. Also, 45% of infected plants were from progeny 676 while 1% was from progenies 689, 693, 694 and 710. Disease severity was from 0.9 in progeny 686 to 4.55 in 676. Wilt index ranged from 131 for progeny 694 and 710 to 495 for progenies 705. Out of the 45 progenies evaluated, 27 were tolerant (1 < 100) and 18 susceptible (1 ≥ 100). Within the tolerant progenies, 4 were significant (1 < 20) while 5 out of 18 were significantly susceptible (1 ≥ 185). Mean yield reduction of the susceptible progenies was 34.8% while in the tolerant progenies, it increased by 9.5% when compared to their controls. Progenies 702, 703 and 709 are recommended for planting based on the level of tolerance to Fusarium wilt disease and yield.

Comparison of aerial and ground spraying applications in controlling fusarium crown rot in wheat

Fusarium crown rot (FCR) is a chronic disease in many regions of the world in wheat, caused by Fusarium culmorum, Fusarium pseudograminearum, and Fusarium graminearum. The operational efficacy of pesticide applications using unmanned aerial vehicles (UAVs) significantly affects the biological efficacy of the pesticides. This study aimed to compare the effectiveness of unmanned aerial vehicle and field sprayer applications in controlling crown rot diseases frequently observed in wheat crops in the Thrace region, Turkey. A licensed fungicide containing the active ingredients, prochloraz plus trifloxystrobin plus cyproconazole mixture was applied to wheat during the ZGS 27 growth stage. The disease severity, disease incidence, and the effectiveness of fungicide treatment on disease severity (%) were evaluated for F. culmorum crown rot disease. The results showed that the severity of the disease during the seedling stage was 11.25% and 18.33% for unmanned aerial vehicle and field sprayer applications, respectively. In the harvest stage, the incidence of disease was 28.33%-39.99% and 48.75%-51.25%, respectively, and the effectiveness of unmanned aerial vehicle application was found to be high, approximately 52%, during the seedling and harvest stages. The unmanned aerial vehicle, acting similarly to the field sprayer, exhibited higher grain quality under conditions of stress from disease. Furthermore, spike weight, grain weight, and number of grains exhibited stronger positive correlations compared to unmanned aerial vehicle treatment. Therefore, unmanned aerial vehicles have promising potential as viable options to manage FCR when the prevailing environmental conditions are not conducive to the use of field sprayer. The results of this research will guide future studies to investigate the efficacy of UAVs on a wider range of pesticides and to further develop the technology to investigate its effectiveness, cost-effectiveness, and sustainability in agricultural applications.

Detection of fusarium head blight using a YOLOv5s-based method improved by attention mechanism

Fusarium head blight (FHB) is one of the most destructive diseases in global wheat production. In order to count the FHB-infected wheat ears under field conditions, this study proposed an algorithm for diseased wheat ear detection based on improved YOLOv5s (Tr-YOLOv5s). The Swin Transformer was used to replace the CSPDarknet backbone network to enhance the extraction of characteristic information of the population wheat ears of FHB in the field background. The convolutional block attention module (CBAM) attention mechanism was added to improve the detection effect of target wheat ears, subsequently improving the overall accuracy of the model. The original loss function complete intersection over union (CIoU) was replaced by Scylla intersection over union (SIoU) loss to accelerate the model convergence and decrease the loss value. The results showed that the mean average precision (mAP) of the Tr-YOLOv5s model reached 90.64%, making a 4.63% improvement compared to the original YOLOv5s model. The improved model could quickly detect and count wheat FHB ear in the field environment, which laid a foundation for the subsequent automatic disease identification and grading of wheat FHB under field conditions.

Effects of Fungi Fusarium sp. to Rhizosphere Soil and Physiological Characteristics of Camellia oleifera Abel.

[Objectives]To study the effects of fungi Fusarium sp.to rhizosphere soil and physiological characteristics of Camellia oleifera Abel.[Methods]We investigated the effects of Fusarium sp.to rhizosphere soil nutrient element content and metabolites of C.oleifera.C.oleifera was inoculated with the suspension of Fusarium sp.in pot experiments and ammonium-N,available phosphorus,available potassi-um,organic matter,enzymes and pH of rhizosphere soil,MDA content,activity of SOD,POD of C.oleifera leaves were analyzed.[Results]Fusarium sp.stress significantly inhibited soil enzyme activities and significantly reduced available phosphorus content,especially for phospha-tase and sucrase.Antioxidant enzyme activities in C.oleifera tissues showed that Fusarium sp.stress significantly increased MDA and SOD enzyme activities and decreased POD enzyme activity.Especially,SOD enzyme activity was elevated by 53.86%compared with the CK group.In addition,analysis of the content of major metabolites in C.oleifera leaves showed that Fusarium sp.stress significantly reduced the content of total flavonoids,quercetin,isoquercitrin and isoquercitrin in C.oleifera leaves by 7.80%,50.00%and 75.90%,respectively.[Conclusions]Our results are an important step which showed strong resistance of C.oleifera and can give a novel insight for researches on the effects in the rhizosphere soil enzyme,soil nutrient elements and metabolites of C.oleifera under the Fusarium sp.too.

一株中华稻蝗内生真菌Fusarium lateritium ZMT01的代谢产物

研究一株中华稻蝗内生真菌Fusarium lateritium ZMT01的代谢产物,采用大米培养基发酵真菌,色谱技术分离纯化单体,波谱分析鉴定结构,共从发酵物中分离鉴定了10个化合物:fusopoltide A(1)、fusopoltide B(2)、fusopoltide D(3)、solaniol(4)、javanicin(5)、(1S,4S,10S)-3,4-dihydro-6,9-dihydroxy-8-methoxy-10(-2-oxopropyl)-1,4-methano-2-benzoxepin-5(1H)-one(6)、2,2′‐methylenebis(4‐methyl‐6‐tert‐butylphenol)(7)、2-hydroxymethyl-5-isopropoxy-4-methoxynaphthalen(8)、β-sitosterol(9)和walterolactone A(10)。其中化合物8、10为首次从Fusarium属中得到,除化合物9外,其他化合物为首次从Fusarium lateritium中分离到。采用二倍稀释法测试抗菌活性,结果显示化合物4和5对O6血清型大肠杆菌Escherichia coli有强抑制活性,MIC为6.25μg/mL,化合物4对尖孢镰孢菌Fusarium oxysporum显示中等抑菌活性,MIC为200μg/mL。

猕猴桃内生真菌Fusarium tricinctum化学成分研究

为研究猕猴桃内生真菌Fusarium tricinctum的固体发酵次级代谢产物及其抗菌活性,采用正/反相硅胶柱色谱、Sephadex LH-20凝胶柱色谱以及HPLC制备等方法,从Fusarium tricinctum的大米发酵提取物中分离得到15个化合物.通过核磁共振、高分辨质谱以及文献调查等方法将化合物结构鉴定为:1H-indole-3-carboxaldehyde(1)、indole-3-acetic acid(2)、indole-3-acetic acid methyl ester(3)、nicotinic acid(4)、N-acetylanthranilic acid(5)、4-hydroxybenzaldehyde(6)、methyl 4-hydroxybenzeneacetate(7)、methyl p-hydroxyphenyl acetate(8)、methyl 4-hydroxy3-methoxyphenylacetate(9)、α-hydroxy-β-phenylpropionic acid(10)、methyl 4-hydroxy-3,5-dimethoxybenzeneacet ate(11)、3,4,5-trimethoxyphenylacetic acid methyl ester(12)、3,7,9-trihydroxy-1-methyl-6H-dibenzo[b,d]pyran-6-one(13)、enniatin B1(14)和enniatin A1(15).化合物14对丁香假单胞杆菌猕猴桃变种(Pseudomonas syringae pv.Actinidiae,Psa)有一定的抑制作用(MIC为25µg/mL).

Fusarium wilt of banana:Current update and sustainable disease control using classical and essential oils approaches

Fusarium species were reported to produce biofilms.Biofilms are superficial societies of microbes bounded and endangered by being situated or taking place outside a cell or cells.The most destructive fungal diseases caused by phytopathogens are as a result of biofilms formation.Fusarium wilt of banana(Panama disease)is caused by a soil-borne pathogen called Fusarium oxysporum f.sp.cubense.Fusarium oxysporum occurs in a form of a species complex(FOSC)which encompasses a crowd of strains.Horizontal genetic factor transfer may donate to the observed assortment in pathogenic strains,while sexual reproduction is unknown in the FOSC.Fusarium wilt is a notorious disease on several crops worldwide.Yield loss caused by this pathogen is huge,and significant to destroy crop yields annually,thereby affecting the producer countries in various continents of the world.The disease is also resistant to various synthetic chemical fungicides.However,excessive use of synthetic fungicides during disease control could be lethal to humans,animals,and plants.This calls for alternative eco-friendly management of this disease by targeting the biofilms formation and finally suppressing this devastating phytopathogen.In this review,we,therefore,described the damage caused by Fusarium wilt disease,the concept of filamentous fungal biofilms,classical control strategies,sustainable disease control strategies using essential oils,and prevention and control of vegetables Fusarium wilt diseases.

Elimination of the yellow pigment gene PSY-E2 tightly linked to the Fusarium head blight resistance gene Fhb7 from Thinopyrum ponticum

Fhb7 is a major gene that was transferred from Thinopyrum ponticum to chromosome 7D of wheat(Triticum aestivum)and confers resistance to both Fusarium head blight(FHB)and Fusarium crown rot(FCR).However,Fhb7 is tightly linked to the PSY-E2 gene,which causes yellow flour,limiting its application in breeding.To break this linkage,marker K-PSY was developed for tagging PSY-E2 and used with Fhb7 markers to identify recombination between the two genes.Screening 21,000 BC1F2 backcross progeny(Chinese Spring ph1bph1b*2/SDAU 2028)revealed two Fhb7^(+)wheat-Tp7el_(2)L lines,Shannong 2–16and Shannong 16–1,that carry a desired truncated Fhb7^(+)translocation segment without PSY-E2.The two lines show levels of resistance to FHB and FCR similar to those of the original translocation line SDAU 2028,but have white flour.To facilitate Fhb7 use in wheat breeding,STS markers were developed and used to isolate Fhb7 on a truncated Tp7el_(2) translocation segment.Near-isogenic lines carrying the Fhb7^(+)segment were generated in the backgrounds of three commercial cultivars,and Fhb7^(+)lines showed increased FHB and FCR resistance without yield penalty.The breakage of the tight linkage between Fhb7 and PSY-E2 via homoeologous recombination provides genetic resources for improvement of wheat resistance to FHB and FCR and permit the large-scale deployment of Fhb7 in breeding using marker-assisted selection.

接触辉光放电等离子体对Fusarium solani的杀菌作用机制及动力学模型研究

为研究接触辉光放电等离子体(CGDP)对茄病镰刀菌(Fusarium solani)的杀菌作用及机制,本试验以Fusarium solani为试材,考察CGDP处理过程中电压、处理时间、抗坏血酸浓度、孢子初始浓度等因素对杀菌效果的影响;并对Fusarium solani生长、孢子形态、细胞膜完整性及过程中所产生的活性粒子进行分析。通过Linear、Weibull和Log-Logistic 3种数学模型分析不同电压下CGDP杀菌动力学特性,以相关系数(R^(2))、精确因子(Af)、偏差因子(Bf)和均方根方差(RMSE)4个参数评价拟合效果。结果表明,CGDP对Fusarium solani孢子有着明显的杀菌效果;升高电压、延长处理时间、降低抗坏血酸浓度和孢子初始浓度均能有效抑制孢子生长,使杀菌效率提高(P<0.05);CGDP处理30 min,活性物质(·OH、H_(2)O_(2)、NO_(3)^(-))浓度分别增加至1.57 mg·L^(-1)、73.89 mmol·L^(-1)和12.72 mg·L^(-1),pH值由7.07降至4.66;孢内核酸和蛋白质的渗漏量以及PI染色和扫描电镜结果表明,CGDP对Fusarium solani的杀菌作用可能是通过破坏孢子形态和细胞膜完整性后被活性物质攻击而引起的;模型拟合结果表明,Weibull模型拟合度最高(R^(2)=0.9242),并且RMSE较小(0.6367),可以用于描述和预测CGDP对Fusarium solani的杀菌动力学特征。本研究结果为低温等离子体杀菌技术和杀菌机制研究提供了理论指导。

Fusarium graminearum sensu stricto和F.asiaticum在玉米秸秆和水稻秸秆上子囊壳形成的比较

为探究麦田前茬作物玉米秸秆和水稻秸秆上中国小麦赤霉病菌的两个优势种Fusarium graminearum sensu stricto(F.graminearum)和F.asiaticum子囊壳形成和发育成熟过程的差异,分别选择3株F.graminearum菌株(SE81,3-ADON型;LcA-2,15-ADON型;HX5-1,NIV型)和2株F.asiaticum菌株(M4A,3-ADON型;M31-2,NIV型),用其孢子悬浮液接种玉米秸秆和水稻秸秆,放置于花泥和地表两种环境条件下,比较接种不同菌株秸秆上子囊壳的形成和发育成熟情况及5个菌株对‘郑麦366’(高感小麦赤霉病品种)的致病力。结果表明:花泥环境下产生子囊壳的速度要快于地表,以玉米秸秆为载体子囊壳产生速度比水稻秸秆快且多数密度大,3个F.graminearum菌株(SE81、LcA-2和HX5-1)在同种秸秆相同环境下比2个F.asiaticum菌株(M4A和M31-2)产生子囊壳的速度快且子囊壳密度大。5个菌株在不同环境的不同秸秆上产生的子囊壳的成熟度均无规律,接种‘郑麦366’后其病情指数间有极显著差异(P<0.01),在花泥和地表的玉米秸秆和水稻秸秆上3次调查的子囊壳密度与‘郑麦366’的病情指数呈显著正相关,不同环境条件下的子囊壳产生速度(AUPGC)与‘郑麦366’的病情指数呈极显著正相关。本研究将为阐明F.graminearum和F.asiaticum在中国小麦赤霉病上表现区域性地理分布的原因提供参考依据。