Stalk Crosscut Identification And Evaluation Of Resistance To Verticillium Wilt And Genome Wide Association Analysis In Cotton

In this study,384 upland cotton core collection population lines were used to investigate and identify the disease resistance traits to solve the problems of accuracy in cotton Verticillium Wilt resistance and the correlation of disease resistance and yield in field.Five environments were performed,which are located at Kuitun(in north Xinjiang,both 2018 and 2019),Alar(in southern Xinjiang,both 2018 and 2019),and Anyang(in Henan Province,2019).The trait of Verticillium wilt resistance on different plant part(upper、middle and lower)and yield were investigated.This study is of great significance in discovering resistance genes and screening elite varieties with comprehensive favorable characters.The main results are as follows:1.There was a significant positive correlation among different cotton stem parts,and the order of disease index was lower>middle>upper,which indicates a holistic and transmissible effect on cotton.There was a significant difference in locations,with the most serious disease at Kuitun,the middle incidence at Anyang,and the least susceptible at Alar.2.Correlation analysis revealed that plant height can be used as a reference index due to the closely relationship between disease resistance and agronomic traits.The relationship between disease resistance and yield traits demonstrated that the cotton yield was influenced most seriously,followed by boll weight and lint percentage,but little effect on boll number.3.Cotton varieties could be divided into five categories according to the cluster analysis of factor scores in SPSS.The results showed that the fourth group(Ⅳ)had the lightest disease index with the heaviest boll weight and the highest yield.And the varieties could be divided into 7 categories according to the disease index of Verticillium wilt in different plant stem parts.The results showed that:the VII group had the highest disease index with the lowest yield;the group I had the lowest disease index with the highest yield.These results were basically consistent with the results of cluster analysis.Two type of varieties(type 1:resistance in upper and tolerance in middle and lower;type 2:tolerance in all stem parts)could be utilized as the resistance reference materials due to the similar higher yield in group Ⅰ、Ⅲ and Ⅳ.4.Twelve resistance cotton accessions were screened initially according to the disease index in different stem parts at five environments,which were Jizi 64,4133bt,Liao 4853,Qik,M-8124-1159,Han 284,Ari3696,Ao siv2,Langhuang F10,Zhong 21371,Jinmian 20,and Ji 169.And 3 final accessions were selected with elite comprehensive characters by the yield traits,which were Jizi 64,4133bt,and Zhong 21371。5.A total of 38 associated SNP locus of Verticillium wilt resistance were detected through GWAS analysis.There were 10 SNP locus at A subgenome and 28 locus in D subgenome.Two haplotypes,CGCA(haplotypel)and TATG(haplotype2),were identified on chromosome D12,and the former was resistant haplotype,the latter was susceptible one.