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.

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.

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.

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.

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。

Identification of a pleiotropic QTL cluster for Fusarium head blight resistance,spikelet compactness,grain number per spike and thousand-grain weight in common wheat

Simultaneously improving Fusarium head blight(FHB)resistance and grain yield is challenging in wheat breeding.The correlations between spikelet compactness(SC),grain number per spike(GNS),thousandgrain weight(TGW)and FHB resistance remains unclear in common wheat.Identification of major quantitative trait loci(QTL)conferring FHB resistance and yield components,and development of breeder-friendly markers for the QTL are prerequisites for marker-assisted selection(MAS).Here,a recombinant inbred line(RIL)population derived from a cross between a resistant cultivar Yangmai 12(YM12)and a susceptible cultivar Yanzhan 1(YZ1)was used to map QTL for FHB resistance and yield components.A total of 22 QTL were identified;among these,six are likely to be new for corresponding traits.A QTL cluster(Qclu.yas-2D)for FHB type II resistance,SC,GNS,and TGW was detected on chromosome 2D.Breeder-friendly kompetitive allele-specific PCR(KASP)markers flanking the interval of Qclu.yas-2D were developed and validated in a diverse panel of 166 wheat cultivars and advanced lines.The YM12 alleles of Qclu.yas-2D significantly increased FHB resistance,SC,and GNS but decreased TGW in the validation population.The KASP markers developed for Qclu.yas-2D have great potential for breeding high-yielding wheat cultivars with enhanced FHB resistance.

FgGyp8 as a putative FgRab1 GAP is required for growth and pathogenesis by regulating FgSnc1-mediated secretory vesicles fusion in Fusarium graminearum

Fusarium graminearum is an important plant pathogenic fungus that causes disease and yield reduction in many cereal crops, such as wheat and barley. Gyp8 stimulates GTP hydrolysis on Ypt1 in yeast. However, the functions of Gyp8 in plant pathogenic fungi are still unknown. In this study, we investigated the roles of Fg Gyp8 in F. graminearum by genetic and pathological analyses. Through gene knockout and phenotypic analyses, we found that Fg Gyp8 is required for vegetative growth in F. graminearum. The conidiation, conidial size and number of septa per conidium of ΔFggyp8 mutant are significantly reduced when compared to the wild type PH-1. Furthermore, Fg Gyp8 is crucial for pathogenicity on wheat coleoptiles and wheat heads. Fg Gyp8 contains a conserved TBC domain. Domain deletion analysis showed that the TBC domain, C-and N-terminal regions of Fg Gyp8 are all important for its biological functions in F. graminearum. Moreover, we showed that Fg Gyp8 catalyzes the hydrolysis of the GTP on Fg Rab1 to GDP in vitro, indicating that Fg Gyp8 is a GTPase-activating protein(GAP) for Fg Rab1. In addition, we demonstrated that Fg Gyp8 is required for Fg Snc1-mediated fusion of secretory vesicles with the plasma membrane in F. graminearum. Finally, we showed that Fg Gyp8 has functional redundancy with another Fg Rab1 GAP, Fg Gyp1, in F. graminearum. Taken together, we conclude that Fg Gyp8 is required for vegetative growth, conidiogenesis, pathogenicity and acts as a GAP for Fg Rab1 in F. graminearum.

Mitochondrial dynamics caused by QoIs and SDHIs fungicides depended on FgDnm1 in Fusarium graminearum

Fusarium head blight(FHB) caused by Fusarium graminearum is a devastating fungal disease on small grain cereal crops,because it reduces yield and quality and causes the mycotoxin contamination to the grain.Dynamins and dynamin-related proteins(DRPs) are large GTPase superfamily members,which are typically involved in the budding and division of vesicles in eukaryotic cells,but their roles in Fusarium spp.remain unexplored.Here,we found that FgDnm1,a DRP and homolog to Dnm1 in Saccharomyces cerevisiae,contributes to the normal fungal growth,sexual reproduction and sensitivity to fungicides.In addition,we found FgDnm1 co-localizes with mitochondria and is involved in toxisome formation and deoxynivalenol(DON) production.Several quinone outside inhibitors(QoIs) and succinate dehydrogenase inhibitors(SDHIs) cause fragmentated morphology of mitochondria.Importantly,the deletion of FgDnm1displays filamentous mitochondria and blocks the mitochondrial fragmentation induced by QoIs and SDHIs.Taken together,our studies uncover the effect of mitochondrial dynamics in fungal normal growth and how such events link to fungicides sensitivity and toxisome formation.Thus,we concluded that altered mitochondrial morphology induced by QoIs and SDHIs depends on FgDnm1.

霸王鞭内生真菌Fusarium sp.DCJ-A发酵物的次生代谢产物研究

采用多种色谱方法对分离自大戟属植物霸王鞭(Euphorbia royleana Boiss)的内生真菌Fusarium sp.DCJ-A的发酵物进行提取和分离,所得化合物的结构通过核磁共振波谱法进行了结构解析,共鉴定了8个化合物,其中包括2个含氧杂环化合物、3个含氮杂环化合物以及3个苯环衍生物,分别为:1 H-imidazole-4-carboxylic acid(1)、4-methlpyrazole-3(5)-carboxylic acid(2)、p-hydroxy phenylacetic acid(3)、methyl-2-(4-hydroxyphenyl)acetate(4)、methyl-4-butyranmiddobenzoate(5)、6-(1-hydroxypentyl)-4-methoxy-2 H-pyran-2-one(6)、(3 S,6R)-6-(l-methylethyl)-3-phenylmethyl-l,4-perhydrooxazine-2,5-dione(7)和xylophone(8),其中化合物2、5、7和8共4个化合物均首次从镰刀菌属Fusarium中分离得到.

Increasing Fusarium verticillioides resistance in maize by genomicsassisted breeding:Methods,progress,and prospects

Maize(Zea mays L.)is an indispensable crop worldwide for food,feed,and bioenergy production.Fusarium verticillioides(F.verticillioides)is a widely distributed phytopathogen and incites multiple destructive diseases in maize:seedling blight,stalk rot,ear rot,and seed rot.As a soil-,seed-,and airborne pathogen,F.verticillioides can survive in soil or plant residue and systemically infect maize via roots,contaminated seed,silks,or external wounds,posing a severe threat to maize production and quality.Infection triggers complex immune responses:induction of defense-response genes,changes in reactive oxygen species,plant hormone levels and oxylipins,and alterations in secondary metabolites such as flavonoids,phenylpropanoids,phenolic compounds,and benzoxazinoid defense compounds.Breeding resistant maize cultivars is the preferred approach to reducing F.verticillioides infection and mycotoxin contamination.Reliable phenotyping systems are prerequisites for elucidating the genetic structure and molecular mechanism of maize resistance to F.verticillioides.Although many F.verticillioides resistance genes have been identified by genome-wide association study,linkage analysis,bulkedsegregant analysis,and various omics technologies,few have been functionally validated and applied in molecular breeding.This review summarizes research progress on the infection cycle of F.verticillioides in maize,phenotyping evaluation systems for F.verticillioides resistance,quantitative trait loci and genes associated with F.verticillioides resistance,and molecular mechanisms underlying maize defense against F.verticillioides,and discusses potential avenues for molecular design breeding to improve maize resistance to F.verticillioides.

ZmMYC7 directly regulates ZmERF147 to increase maize resistance to Fusarium graminearum

The jasmonic acid(JA)signaling pathway is involved in plant growth,development,and response to abiotic or biotic stresses.MYC2,a bHLH transcription factor,is a regulatory hub in the pathway.The function of ZmMYC7,a putative MYC2 ortholog,in jasmonate-signaled defense responses of maize has not been reported.In this study,we found that ZmMYC7 possesses JID,TAD,bHLH and Zip domains and essential characteristics of transcription factors:a nuclear location and transactivation activity.The ZmMYC7mutants showed markedly increased sensitivity to Fusarium graminearum and Setosphaeria turcica.The expression levels of the defense-associated genes ZmPR1,ZmPR2,ZmPR3,ZmPR5,ZmPR6,and ZmPR7 in response to F.graminearum infection were downregulated in ZmMYC7 mutants,while ZmPR4 and ZmPR10 were up-regulated.ZmMYC7 interacted with members of the ZmJAZ family,including ZmJAZ8,ZmJAZ11,and ZmJAZ12.ZmMYC7 physically interacted with G-box cis-elements in the ZmERF147 promoter in vitro and transcriptional activation of ZmERF147 by ZmMYC7 was inhibited by ZmJAZ11 and ZmJAZ12.ZmERF147 mutants were more susceptible to F.graminearum infection than inbred line B73with concomitant down-regulation of all defense-associated ZmPRs except ZmPR4.These findings indicate that ZmMYC7 functions in maize resistance to F.graminearum and sheds light on maize defense responses to pathogenic fungi via the JA signaling pathway.

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.

Changes in concentrations and transcripts of plant hormones in wheat seedling roots in response to Fusarium crown rot

Fusarium crown rot(FCR) is a soilborne disease causing severe yield losses in many wheat-growing areas of the world. Diseased plants show browning and necrosis of roots and stems causing white heads at maturity. Little is known about the molecular processes employed by wheat roots to respond to the disease. We characterized morphological, transcriptional and hormonal changes in wheat seedling roots following challenge with Fusarium pseudograminearum(Fp), the main pathogen of FCR. The pathogen inhibited root development to various extents depending on plants' resistance level. Many genes responsive to FCR infection in wheat roots were enriched in plant hormone pathways. The contents of compounds involved in biosynthesis and metabolism of jasmonic acid, salicylic acid, cytokinin and auxin were drastically changed in roots at five days post-inoculation. Presoaking seeds in methyl jasmonate for 24 h promoted FCR resistance, whereas presoaking with cytokinin 6-benzylaminopurine made plants more susceptible. Overexpression of TaOPR3, a gene involved in jasmonic acid biosynthesis, enhanced plant resistance as well as root and shoot growth during infection.