Genome Analysis Of Cowpea Fusarium Wilt Pathogen And Screening Of Cowpea Fusarium Wilt Resistant Germplasm Resources

Vigna unguiculata(L.)walp,it is a leguminous cowpea annual herb with important economic value in China,with an annual planting area of about 50000 hectares.With the extension of cultivation years,the occurrence of cowpea diseases has increased year by year,especially the Fusarium wilt caused by Fusarium oxysporum has become one of the main factors hindering the development of cowpea industry.Taking Hainan cowpea Fusarium wilt pathogen and 104 cowpea germplasm resources as research materials,this study studied cowpea Fusarium wilt disease and disease resistant germplasm resources from five aspects: genome analysis of cowpea Fusarium wilt pathogen,indoor pesticide screening,disease resistant germplasm resources screening,determination of defense enzyme activity and malondialdehyde content of resistant and susceptible germplasm,and investigation of field agronomic characters.The purpose is to provide a theoretical basis for the breeding of cowpea varieties resistant to Fusarium wilt and the study of disease resistance mechanism.The results are as follows:1.Via Illumina hiseq × 10 platform analysis of the whole genome of JDKW-2strain,the pathogen of cowpea Fusarium wilt,showed that the genome size of the pathogen was 32.64 Mb,the scaffold was 34,and the GC content was 53.70%.A total of 9291 protein genes were predicted by glimmer 3.0 and Gene Mark S software.COG,KEGG and GO annotated 8075,1018 and 6663 genes respectively.These genes mainly have the functions of cell synthesis,metabolism,replication,repair and transcription.A total of 102 t RNAs,23 5s RNAs,3 5.8s RNAs,and 3 28 s RNAs were predicted by the software of r RNAmmer and t RNAascan.Among the 2445 genes annotated by PHI,37.50% are related to toxin,which is also the most,followed by extracellular enzymes and secretory system genes that may be involved in regulating the interaction between pathogen and host.In addition,the catabolic enzyme and cellulase genes in the glycoside hydrolase family annotated by CAZy and the genes related to lignin decomposition can participate in the degradation of cell wall,which helps the pathogen infect cowpea plants and lead to cowpea Fusarium wilt.2.The results showed that several chemical fungicides had certain inhibitory effect on the mycelium of the pathogen,including 25% Bromothalonil·Nonylphenolsulfonate Copper,32.5% Difenconazole·Azoxystrobin,68.75% Fluopicolide·Propamocarb and27.12% Copper dihydroxosulphate had the best inhibition effect on the mycelium of cowpea Fusarium wilt strain JDKW-2.The concentration for 50% of maximal effect of these chemicals were 0.199 μg/m L,0.004 μg/m L,3.002 μg/m L and 1.564 μg/m L,respectively.3.The resistance of 104 cowpea germplasm resources to Fusarium wilt was identified by indoor root cutting and soaking method.The results showed that there were 5 varieties with highly resistance,accounting for 4.81%;27 resistant varieties,accounting for 25.96%;30 medium resistant varieties,accounting for 28.85%;36susceptible varieties,accounting for 34.62%;there were 6 highly susceptible varieties,accounting for 5.77%.Among them,Qiangliyoubaidoujiao,Jipinhaitewang,Qingyi fairy,China wufengsheng and Liujiang No.8 are highly resistance,and Linfengchangdibai,Mingcui,Zhangtangwang,Huaguniang·Pangerjiang,Chunqiuzhaibujing and Gaochanlvguanwang are highly sensitivity.4.The defense enzyme activity and malondialdehyde content of highly resistant variety No.1(Qiangliyoubaidoujiao)and highly susceptible variety No.80(Huaguniang · Pangerjiang)were determined.The differences in the expression of defense enzymes and malondialdehyde(MDA)of roots and stems of cowpea were determined by studying the changes of defense enzyme activity and malondialdehyde(MDA)content in the roots and stems of cowpea.It was found that after inoculation with cowpea Fusarium wilt strain JDKW-2,the activities of POD,PPO,SOD,PAL,CAT and β-1,3-GA in highly resistant varieties or the peak of enzyme activity was earlier than that in highly susceptible varieties,or the change range of enzyme activity was greater than that in highly susceptible varieties,and the content of MDA in highly resistant varieties was also higher than that in highly susceptible varieties.5.The 104 tested cowpea germplasm resources were planted in the field,and the relevant agronomic characters were analyzed.24 main agronomic characters were selected for investigation.Through the analysis of principal component,correlation,clustering and grey correlation method,and comprehensive evaluation,8 varieties were finally selected,including Qiangliyoubaidoujiao,Rejiang No.1,Dafengshou,lvbatianxia,Linfengbaijiangwang,Linfengzhenruyi,Heshun and Hanmei No.8.These varieties have excellent phenotypes,the ability of resistance to Fusarium wilt is the strongest and the yield is the highest.It provides materials for the research of breeding high-yield resistance to Fusarium wilt and provides reference for improving the economic value of cowpea.