Identification, pathogenicity, and fungicide sensitivity of Eutiarosporella dactylidis associated with leaf blight on maize in China

Maize(Zea mays L.) is an economically vital grain crop that is cultivated worldwide. In 2011, a maize foliar disease was detected in Lingtai and Lintao counties in Gansu Province, China. The characteristic signs and symptoms of this disease include irregular chlorotic lesions on the tips and edges of infected leaves and black punctate fruiting bodies in dead leaf tissues. Given favourable environmental conditions, this disease spread to areas surrounding Gansu. In this study, infected leaves were collected from Gansu and Ningxia Hui Autonomous Region between 2018and 2020 to identify the disease-causing pathogen. Based on morphological features, pathogenicity tests, and multilocus phylogenetic analysis involving internal transcribed spacer(ITS), 18S small subunit rDNA(SSU), 28S large subunit rDNA(LSU), translation elongation factor 1-alpha(TEF), and β-tubulin(TUB) sequences, Eutiarosporella dactylidis was identified as the causative pathogen of this newly discovered leaf blight. Furthermore, an in vitro bioassay was conducted on representative strains using six fungicides, and both fludioxonil and carbendazim were found to significantly inhibit the mycelial growth of E. dactylidis. The results of this study provide a reference for the detection and management of Eutiarosporella leaf blight.

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.

Exploration of cyclooxygenase-2 inhibitory peptides from walnut dreg proteins based on in silico and in vitro analysis

Walnut dreg protein hydrolysates(WDPHs)exhibit a variety of biological activities,however,the cyclooxygenase-2(COX-2)inhibitory peptide of WDPHs remain unclear.The aim of this study was to rapidly screen for such peptides in WDPHs through a combination of in silico and in vitro analysis.In total,1262 peptide sequences were observed by nano liquid chromatography/tandem mass spectrometry(nano LC-MS/MS)and 4 novel COX-2 inhibitory peptides(AGFP,FPGA,LFPD,and VGFP)were identified.Enzyme kinetic data indicated that AGFP,FPGA,and LFPD displayed mixed-type COX-2 inhibition,whereas VGFP was a non-competitive inhibitor.This is mainly because the peptides form hydrogen bonds and hydrophobic interactions with residues in the COX-2 active site.These results demonstrate that computer analysis combined with in vitro evaluation allows for rapid screening of COX-2 inhibitory peptides in walnut protein dregs.

Development of Spectral Features for Monitoring Rice Bacterial Leaf Blight Disease Using Broad-Band Remote Sensing Systems

As an important rice disease, rice bacterial leaf blight (RBLB, caused by the bacterium Xanthomonas oryzae pv.oryzae), has become widespread in east China in recent years. Significant losses in rice yield occurred as a result ofthe disease’s epidemic, making it imperative to monitor RBLB at a large scale. With the development of remotesensing technology, the broad-band sensors equipped with red-edge channels over multiple spatial resolutionsoffer numerous available data for large-scale monitoring of rice diseases. However, RBLB is characterized by rapiddispersal under suitable conditions, making it difficult to track the disease at a regional scale with a single sensorin practice. Therefore, it is necessary to identify or construct features that are effective across different sensors formonitoring RBLB. To achieve this goal, the spectral response of RBLB was first analyzed based on the canopyhyperspectral data. Using the relative spectral response (RSR) functions of four representative satellite or UAVsensors (i.e., Sentinel-2, GF-6, Planet, and Rededge-M) and the hyperspectral data, the corresponding broad-bandspectral data was simulated. According to a thorough band combination and sensitivity analysis, two novel spectralindices for monitoring RBLB that can be effective across multiple sensors (i.e., RBBRI and RBBDI) weredeveloped. An optimal feature set that includes the two novel indices and a classical vegetation index was formed.The capability of such a feature set in monitoring RBLB was assessed via FLDA and SVM algorithms. The resultdemonstrated that both constructed novel indices exhibited high sensitivity to the disease across multiple sensors.Meanwhile, the feature set yielded an overall accuracy above 90% for all sensors, which indicates its cross-sensorgenerality in monitoring RBLB. The outcome of this research permits disease monitoring with different remotesensing data over a large scale.

Development, Delivery and Evaluation of a Safety Training Program on Demolition for Blight Reduction

The main objective of the work presented in this paper was to develop a customized safety training program that can be incorporated into the demolition projects undertaken as part of blight reduction efforts in urban centers. A subsidiary objective was to devise and implement a safety program evaluation methodology, and gain insights on the relationships between knowledge acquisition through training and trainee demographics. Salient aspects of blight elimination efforts, as well as the main facets of building demolition practices and requirements, were reviewed. Information on various related safety and health hazards was studied in depth with a focus on demolition operations dealing with blighted properties. A unique safety hazard awareness training program was created for demolition workers, contractors and inspectors based on this research. In addition to devising a curriculum of relevant training topics along with traditional and online delivery systems to be employed, effectiveness evaluation instruments were formulated. Based on the limited data collected from the trainees it was concluded that the program was well-received by them and provided effective learning. It was also found that no statistically significant associations existed between the knowledge gain of the trainees, and either their experience level or union status, after taking this training.

Chemical composition of walnuts from three regions in China

To reveal the characteristic chemicals of walnuts from different origins, we analyzed fatty acid composition,tocopherols, phytosterols and total phenolic content (TPC) of walnuts from three main producing regions inChina. The results showed that walnuts were rich in polyunsaturated fatty acids, and the ratio of ω-6 to ω-3 fattyacids was close to the recommendation of Chinese Nutrition Society. Moreover, walnuts contain high contents oftocopherols (331.20–414.71 mg/kg), phytosterols (97.17–110.35 mg/100 g) and phenols (38.51–48.08 mg GAE/kg). Significant chemical differences exist among walnuts from three production regions. The highest content ofpolyunsaturated fatty acids was found in walnuts from the northern China, the highest content of tocopherols inwalnuts from southwest China, and the highest contents of phytosterol and TPC in walnuts from northwest China.However, there was no significant difference in the tocopherol, phytosterol and TPC content of walnuts betweenthe Northern China and Northwest China. The above results provide important references for manufacturers andconsumers to select suitable walnut scientifically and reasonably.

In Vitro Efficacy Assessment of Botanical Extracts against Botrytis gladiolorum Causing Gladiolus Leaf Blight

An experiment was conducted at the Mycology laboratory, Department of Plant Pathology, Sher-e-Bangla Agricultural University, Dhaka, Bangladesh to find out the efficacy of selected botanical extracts against Botrytis gladiolorum (Bg) causing gladiolus leaf blight. Infected leaves samples were collected from gladiolus farmers’ field and brought to the laboratory for study. Ten selected botanicals were used against the colony growth of (Bg). The botanicals were Mehendi, Chrysanthemum, Basil (Tulsi), Onion, Neem, Bael, Arjuna, Garlic, Aloevera (Ghritkumary) and Turmeric. Botanical extracts were applied at the rate of 5%, 10% and 20%. The radial mycelia growth was found minimum (11.60 mm) in garlic extract treated plate at the dose of 5% at 5 DAI, which was statistically similar with turmeric extract treated (14.00 mm) plate and the inhibition of growth was 60% and 51.72%, respectively. Similar trend was found at 10 DAI and 15 DAI. At 15 DAI, garlic and turmeric extract gave the best result against Bg, which was statistically similar with onion (50.07% inhibition) and mehendi (49.93%). All botanicals showed significantly different results over control and found effective in reducing the mycelial growth at the dose of 10%. At 5 DAI, no radial mycelia growth was found in garlic treated plate, which was statistically similar with onion treated plate, means that the inhibition of growth was 100%. Similar trend was also found at 10 DAI, and 15 DAI but at 15 DAI, onion (30.20 mm) gave the statistically similar results with Garlic (30.10 mm) and the mycelia growth inhibition was (57.70%) and (57.84%), respectively. In case of 20% dose, garlic extract showed the best result at 5 DAI and the radial mycelia growth was found minimum (00.00 mm) which was statistically similar with onion extract treated (00.00 mm) plate and turmeric extract treated plate. The inhibition of growth was 100%. At 15 DAI, the inhibition of fungal growth was found (73.74%), (71.23%) and (66.90%), respectively with treated by turmeric (18.80 mm), garlic (20.60 mm) and onion (23.70 mm).

The Physiological and Molecular Responses of Exogenous Selenium to Selenium Content and Fruit Quality in Walnut

To study the effect of exogenous selenium on fruit quality in walnut(Juglans regia L.),8-year-old walnut(Qingxiang)was taken as the research object.In the fruit expansion stage,300 mg/L of sodium selenate,yeast selenium and sodium selenite solutions were applied on the leaf of walnut,and the selenium levels in leaves,pericarp and kernel were determined at the ripening stage.The fruit quality,mineral nutrient content,antioxidant enzyme activity,and related genes’expression were analyzed.The results showed that the three exogenous selenium increased the selenium levels in leaves,pericarp and kernel of walnut.They also significantly increased fruit and kernel weights,and kernel linoleic acid,but markedly decreased kernel crude fat and saturated fatty acid.Selenium spraying promoted the absorption of mineral nutrients such as potassium and zinc,but inhibited the absorption of calcium,and had no significant effect on iron and magnesium in the kernel.Three exogenous selenium increased the activities of superoxide dismutase(SOD),peroxidase(POD),ascorbate peroxidase(APX),and catalase(CAT)significantly in the kernel.Except for sodium selenate treatment significantly reduced malondialdehyde(MDA)content in the kernel,the other two selenium sources treatments had no significant effect on MDA and hydrogen peroxide(H2O2)levels.They also increased the expression of JrCu/Zn-SOD,Jr2-Cys POD,JrCyt-APX and JrCAT in kernel,to different extents.These implies that,in the walnut fruit enlargement period,the foliar spraying selenium could increase the selenium content of walnut,affect the mineral nutrient absorption,improve the antioxidant capacity and related genes’expression,and reduce the degree of peroxide,and then improve the quality of fruit.Furthermore,yeast selenium showed the comprehensive effect of the best.

Simulation Analysis of Stress Field of Walnut Shell Composite Powder in Laser Additive Manufacturing Forming

A calculation model of stress field in laser additive manufacturing of walnut shell composite powder(walnut shell/Co-PES powder)was established.The DFLUX subroutine was used to implement the moveable application of a double ellipsoid heat source by considering the mechanical properties varying with temperature.The stress field was simulated by the sequential coupling method,and the experimental results were in good accordance with the simulation results.In addition,the distribution and variation of stress and strain field were obtained in the process of laser additive manufacturing of walnut shell composite powder.The displacement of laser additive manufacturing walnut shell composite parts gradually decreased with increasing preheating temperature,decreasing laser power and increasing scanning speed.During the cooling process,the displacement of laser additive manufacturing of walnut shell composite parts gradually increased with the increasing preheating temperature,decreasing scanning speed and increasing laser power.

Rice ferredoxin OsFd4 contributes to oxidative stress tolerance but compromises defense against blight bacteria

Ferredoxins(Fds)in plastids are the most upstream stromal electron receptors shuttling electrons to downstream metabolic systems and function in various physiological processes of dicots,but their roles in monocots’response to stresses are still unclear.In this study,the functions of OsFd4,the major non-photosynthetic type Fd in rice,were characterized under oxidative stress and Xanthomonas oryzae pv.oryzae(Xoo)infection.OsFd4-knockout mutants displayed no defects in key agronomic traits and blast resistance,but were more sensitive to hydrogen peroxide(H2O2)treatment than the wild type.Transient expression of OsFd4 alleviated H2O2-induced rice cell death,suggesting that OsFd4 contributes to rice tolerance to exogenous oxidative stress.Deletion of OsFd4 enhanced rice immune responses against Xoo.OsFd4 formed a complex in vivo with itself and OsFd1,the major photosynthetic Fd in rice,and OsFd1 transcripts were increased in leaf and root tissues of the OsFd4-knockout mutants.These results indicate that OsFd4 is involved in regulating rice defense against stresses and interplays with OsFd1.

Effect of Dandelion(Taraxacum mongolicum Hand.-Mazz.)Intercropping with Different Plant Spacing on Blight and Growth of Pepper(Capsicum annuum L.)

Intercropping of crops that can secrete bacteriostatic active substances can not only inhibit the occurrence of disease but also have an important effect on plant growth.However,the effects of dandelion intercropping on pepper blight control and pepper growth remain unclear.In this study,the control effect of dandelion on pepper blight was studied by inoculating the pepper leaves with Phytophthora infestans,and it also discusses the correlation of the occurrence of pepper epidemic disease with the pepper canopy environment,soil environment,pepper photo-synthesis,and yield index.The results showed that best plant distance for dandelion intercropping was 20 cm(P20),and the control effect reached 43.31%.As compared to the CK,SOD enzyme,POD enzyme,and PAL enzyme were significantly up-regulated during the growth of pepper;chlorophyll content in pepper leaves was significantly increased;photosynthetic characteristics were significantly increased;stem diameter and yield of crop pepper were effectively improved;and the quality of the pepper product was better,but intercropping dandelion resulted in a significant decrease of nutrients in the soil environment of pepper,so a reasonable intercropping distance was needed.The correlation analysis shows that the incidence of pepper blight(A)was significantly positively correlated with soil temperature(Q),intercellular carbon dioxide(L),and canopy air temperature(O).The incidence of capsicum blight(A)was significantly negatively correlated with chlorophyll content(F),net photo-synthetic rate(K),stomatal conductance(M),ww rate(N),soil sucrase activity(W),vitamin C(AB),and leaf PAL enzyme(J).Finally,it was deduced that intercropping dandelion could effectively control the occurrence of pepper blight while also demonstrating a complex interaction with the pepper growing environment.

Molecular Screening of Rice Cultivated in Benin for the Identification of Xanthomonas oryzae Pv. oryzae and Bacterial Leaf Blight Resistance Genes

One of the most devastating diseases of rice worldwide is bacterial blight (BLB) caused by Xanthomonas oryzae pv. Oryzae (Xoo). In Benin, Xoo was first described in 2013 on wild rice Oryzae longistaminata. So far, no study has been done on Beninese Xoo strains. We do not know whether the pathogen has already passed into the rice varieties grown, or if they are exposed to other bacteria. Whereas the use of resistant varieties, carrying resistance genes, is the only highly effective and environmentally friendly way to control this disease, no information is available on these Xoo resistance genes in rice varieties grown in Benin apart from the one we recently. This study aims to identify Beninese Xoo strains, causing BLB and screen rice varieties grown in Benin for the main resistance genes. Diseased rice leaves showing typical symptoms of fire blight collected from different rice fields in the three phytogeographic areas of Benin were analyzed by PCR for Xoo-specific sequence identification. Furthermore, seventy-five collected rice accessions were screened to identify xa5, Xa7, xa13, and Xa21 resistance genes to Xoo. The results reveal that Xanthomonas oryzae was identified in two fields in Banikouara and one in Malanville. On the other hand, Sphingomonas sp. has been identified in several other rice fields in Benin. Forty-seven of seventy-five rice accessions examined (62.66%) carried Xoo resistance genes with 3 (4%) and 40 (53.33%) of xa5 and Xa21 respectively. None of the accessions had either Xa7 or xa13 resistance genes. Three accessions possess both xa5 and Xa21 genes. Isogenic lines IRBB60 and IRBB21, supposed to be a positive control, presented a Xoo sensitivity allele. These results indicate that Xoo has moved from the wild rice variety to the cultivated variety in northern Benin and varietal improvement programs must be implemented with varieties having several resistance genes for the efficient response against a possible BLB pandemic in Benin.

Synthesis of Modified Walnut Shell Biochar and Its Performance of Cadmium Adsorption

Biochar is a functional and environmentally friendly material mainly made from by-products of industrial and agricultural production as raw material, which is cracked at high temperatures and slow speeds. The preparation of biochar requires the thermochemical conversion of biomass in an oxygen-restricted environment. Different raw materials and preparation processes result in biochar with different internal structures and biofunctional groups, which often have different properties. Adsorption of heavy metal pollutants is one of the main research directions for biochar application, and there are still areas that can be improved in the current research for biochar for treating heavy metal wastewater. In this study, we take the treatment of cadmium-containing wastewater as an example, walnut shell biochar (WSBC) as a carrier, iron(VI) compounds as a modifying reagent, and test the performance of cadmium-containing wastewater treatment using simulated cadmium-containing wastewater by adjusting the pyrolysis process and modification method at the same time to find the optimal experimental scheme, and give a reasonable theoretical explanation in relation to the results of the characterization tests, such as SEM, FT-IR, and so on. The characterized results show that iron(VI) compound (K2FeO4)-modified WSBC has a significant ability to remove cadmium contamination in the wastewater (remove 96.62% of cadmium in 1 minute), and its structure is different from other iron compound-modified ones. The aim of this study is to improve the efficiency of cadmium adsorption by specific types of biochar, while realizing the whole process as environmentally friendly as possible.

Marker-assisted selection to pyramid Fusarium head blight resistance loci Fhb1 and Fhb2 in the high-quality soft wheat cultivar Yangmai 15

Fusarium head blight(FHB)is one of the most detrimental wheat diseases which greatly decreases the yield and grain quality,especially in the middle and lower reaches of the Yangtze River of China.Fhb1 and Fhb2 are two major resistance loci against Fusarium graminearum.Yangmai 15(YM15)is one of the most popular varieties in the middle and lower reaches of the Yangtze River,and it has good weak gluten characters but poor resistance to FHB.Here we used Fhb1 and Fhb2 to improve the FHB resistance of YM15 by a molecular marker-assisted selection(MAS)backcrossing strategy.The selection of agronomic traits was performed for each generation.We successfully selected seven introgressed lines which carry homozygous Fhb1 and Fhb2 with significantly higher FHB resistance than the recurrent parent YM15.Three of the introgressed lines had agronomic and quality characters that were similar to YM15.This study demonstrates that the pyramiding of Fhb1 and Fhb2 could significantly improve the FHB resistance in wheat using the MAS approach.

Characterization and Pathogenicity of Pseudopestalotiopsis vietnamensis Causing Gray Blight of Wuyi Rock Tea(Camellia sinensis)in China and Specific Mechanisms of Disease Infection

Gray blight disease(GBD)causes significant losses in tea production in China.Although genes and biological processes involved in resistance to fungal disease in tea plants have been identified,specific mechanisms of the GBD infection process remain unknown.In this study,morphological and multi-gene(TEF-TUB-ITS)phylogenetic characteristics were used to identify isolate CLBB1 of Pseudopestalotiopsis vietnamensis.Pathogenicity tests confirmed that isolate CLBB1 from tea leaves caused GBD in the susceptible tea cultivar Wuyi Rock(Camellia sinensis var.sinensis cv.Shuixian).Spores began to germinate 24 h after infection(hai),and after 48 h,elongated fungal hyphae formed from a single conidium.Transcriptome analysis revealed that 482,517,and 369 genes were differentially expressed at 24,48,and 72 hai,respectively,in Wuyi Rock tea leaves.Isolate CLBB1 infection elicited phenotype-related responses and activated defense-related pathways,including plant–pathogen interaction,MAPK signaling,and plant hormone signal transduction,suggesting a possible mechanism underlying phenotype-based susceptibility to CLBB1.Thus,a new Ps.vietnamensis strain causing GBD in the tea cultivar‘Shuixian’was discovered in this study.Transcriptome analysis indicated that pathogen invasion activated chitin-related MAPK pathways and that tea plants required a hormone to restrict CLBB1.

In vitro and in silico studies of salicylic acid on systemic induced resistance against bacterial leaf blight disease and enhancement of crop yield

Salicylic acid(SA)is an effective elicitor to promote plant defenses and growth.This study aimed to investigate rice(Oryza sativa L.)cv.Khao Dawk Mali 105 treated with salicylic acid(SA)-Ricemate as an enhanced plant protection mechanism against bacterial leaf blight(BLB)disease caused by Xanthomonas oryzae pv.oryzae(Xoo).Results indicated that the use of SA-Ricemate as a foliar spray at concentrations of more than 100 mg L^(-1)can reduce the severity of BLB disease by 71%.SA-Ricemate treatment also increased the hydrogen peroxide(H_(2)O_(2))content of rice leaf tissues over untreated samples by 39–61%.Malondialdehyde(MDA)in rice leaves treated with SA-Ricemate also showed an increase of 50–65%when comparing to non-treated samples.The differential development of these defense compounds was faster and distinct when the SA-Ricemate-treated rice was infected with Xoo,indicating plant-induced resistance.Besides,SA-Ricemate elicitor at a concentration of 50–250 mg L^(-1)was correlated with a substantial increase in the accumulation of total chlorophyll content at 2.53–2.73 mg g^(-1)of fresh weight which suggests that plant growth is activated by SA-Ricemate.The catalase-and aldehyde dehydrogenase-binding sites were searched for using the CASTp server,and the findings were compared to the template.Chemsketch was used to design and optimize SA,which was then docked to the catalase and aldehyde dehydrogenase-binding domains of the enzymes using the GOLD 3.0.1 Software.SA is shown in several docked conformations with the enzymes catalase and aldehyde dehydrogenase.All three catalase amino acids(GLN7,VAL27,and GLU38)were discovered to be involved in the creation of a strong hydrogen bond with SA when SA was present.In this mechanism,the aldehyde dehydrogenase amino acids LYS5,HIS6,and ASP2 were all implicated,and these amino acids created strong hydrogen bonds with SA.In field conditions,SA-Ricemate significantly reduced disease severity by 78%and the total grain yield was significantly increased which was an increase of plant height,tiller per hill,and panicle in three field trials during Aug–Nov 2017 and 2018.Therefore,SA-Ricemate can be used as an alternative elicitor on replacing harmful pesticides to control BLB disease with a high potential of increasing rice defenses,growth,and yield components.

Exploring the nano-fungicidal efficacy of green synthesized magnesium oxide nanoparticles(MgO NPs)on the development,physiology,and infection of carrot(Daucus carota L.)with Alternaria leaf blight(ALB):Molecular docking

In this research,green synthesized magnesium oxide nanoparticles(MgO NPs)from lemon fruit extracts and their fungicidal potential was evaluated against Alternaria dauci infection on carrot(Daucus carota L.)under greenhouse conditions.The scanning and transmission electron microscopy(SEM and TEM)and ultra-violet(UV)visible spectroscopy were used to validate and characterize MgO NPs.The crystalline nature of MgONPs was determined using selected area electron diffraction(SAED).MgO NPs triggered substantial antifungal activity against A.dauci when exposed to 50 and 100 mg L^(–1)concentrations but the higher antifungal potential was noticed in 100 mg L^(–1)under invitro conditions.In fungal inoculated plants,a marked decrease in growth,photosynthetic pigments,and an increase in phenol,proline contents,and defense-related enzymes of carrot were seen over control(distilled water).However,foliar application of MgO NPs at 50 and 100 mg L^(–1)resulted in significant improvement of plant growth,photosynthetic pigments,phenol and proline contents,and defense enzymes activity of carrots with and without A.dauci infection.Spraying of MgO NPs at 100 mg L^(–1)had more plant length(17.11%),shoot dry weight(34.38%),plant fresh weight(20.46%),and root dry weight(49.09%)in carrots when challenged with A.dauci over inoculated control.The leaf blight indices and percent disease severity were also reduced in A.dauci inoculated plants when sprayed with MgO NPs.The non-bonding interactions of Alternaria genus protein with nanoparticles were studied using molecular docking.

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.

Intron Retention Fine-Tunes the Resistance of the Rice Mutant pls4 to Rice Sheath Blight(Rhizotonia solani AG I.1a)

OsPLS4 encodes aβ-ketoacyl carrier protein reductase(KAR).The role of OsPLS4 in rice sheath blight(Rhizoctonia solani)remains unclear.Our preliminary studies showed that premature leaf senescence mutants(pls4)were highly susceptive to sheath blight in the early stage of rice development.To explore the role of this gene in the development of rice sheath blight,the transcriptome profiles of the rice pls4 mutant and wild type were compared by RNA-seq.The results revealed 2,569 differentially expressed genes(DEGs).The down-regulated genes were significantly enriched in the defense response-related biological processes.These down-regulated genes included the chitinase genes and WRKY genes,which were significantly changed in pls4 mutants.Furthermore,467 genes induced significant alternative splicing(AS)events.Among them,intron retention(IR)affected gene expression levels and functions of the vitamin B6(VB6)metabolism pathway related to sheath blight.This result suggests that IR plays an important role in the sheath blight resistance of mutant pls4.Together,these results indicate that pls4 could be involved in the biological process of sheath blight via DEGs and the fine-tuning of IR.The present study provides a molecular basis for further investigation of the resistance of rice to sheath blight.

Codominance Functional Marker of Bacterial Blight Resistance Gene Xa7 in Rice

[Objectives]A codominance functional marker of the broad-spectrum bacterial blight resistance gene,Xa7,of rice was identified for accurate detection,generation tracking,and differentiation between homozygous and hemizygous genotypes of the gene.[Methods]A potential functional marker containing four primers was designed using Premier 5 software and based on the differences on the sequences of Xa7,xa7,and allele-free genomes.The molecular distinctness of the marker in different materials was verified by PCR.Three crossbreed lines of Xa7 and their parents were inoculated with seven bacterial blight strains at the booting stage to examine the affected agronomic traits at maturation.[Results]The homozygous R084 of Xa7 could be amplified into a 91 bp band and the Nip free of allele with a 153 bp band,while the heterozygote Nip/R084,91 bp and 153 bp bands.The candidate codominance marker,Xa7fun,amplified fragments that matched the predicted target bands.No 91 bp fragment was amplified from 18 germplasms of varied types,indicating a lack of Xa7 in them.Whereas Ry1,Ry2 and Ry3 had a 91 bp band,suggesting the inclusion of homozygous Xa7.Under an elevated temperature,Huazhan responded to the seven bacterial blight pathogens as highly susceptible(HS),intermediate susceptible(MS),or susceptible(S);R084 to six of the seven pathogens(HNA1-4,FuJ,GDA2,GD1358,PX086,and YN24)as highly resistant(HR),intermediate resistant(MR)or resistant(R);Ry-1 to five pathogens(GDA2,HNA1-4,FuJ,GD1358,and YN24)as HR or MR;Ry-2 to five pathogens(GDA2,GD1358,HNA1-4,PXO86,and YN24)as HR or R;and Ry-3 to 6 pathogens(HNA1-4,FuJ,GDA2,GD1358,PXO86,and YN24)as HR or MR.Therefore,the infiltration of Xa7 in the improved crossbred lines RY-1,RY-2,and RY-3 significantly accentuated the blight resistance of Huazhan.[Conclusions]Homozygous or hemizygous Xa7 could be accurately differentiated by the currently identified codominance functional marker Xa7 fun.The Xa7 introgression did not significantly alter the critical agronomic traits in the hybridization from generation to generation and could be safely applied in breeding rice varieties with bacterial blight resistance.