干旱胁迫下玉米雄穗结构性状的GWAS及全基因组选择OA

Drought is a major abiotic stress that affects maize growth and development,leading to reduced yield.Tassel length(TL)and tassel primary branch number(TBN)are key structural traits influencing pollen dispersal and yield formation in maize.Elucidating the genetic basis of TL and TBN under drought stress provides theoretical support for breeding drought-tolerant and stable-yielding maize varieties.In this study,an association panel consisting of 395 maize inbred lines was subjected to multi-environment phenotyping under well-watered(WW)and drought-stressed(DS)conditions.High-density SNP markers ob-tained from resequencing were used to perform genome-wide association studies(GWAS)and genomic selection(GS)with the FarmCPU model.TL,TBN,and their drought resistance indices were significantly affected by environment,genotype,and geno-type×environment interaction.Drought stress significantly reduced the phenotypic values of TL and TBN(P<0.0001).Both TL and TBN exhibited high heritability under WW and DS,ranging from 72.12%to 90.19%.The heritability of the drought resis-tance index was 57.43%for TL and 86.22%for TBN.GWAS identified multiple SNPs significantly associated with TL,TBN,and their drought resistance indices.Specifically,71 and 51 SNPs were associated with TL under WW and DS,respectively,while 70 and 81 SNPs were associated with TBN under WW and DS conditions,respectively.Some significant SNPs were repeatedly de-tected under different water regimes or in the drought resistance index analysis,indicating certain environmental stability.Among them,three co-localized SNPs were detected across WW,DS,and drought resistance index analyses,and ten co-localized SNPs were found between DS and the drought resistance index.For TBN,six co-localized SNPs were identified across WW,DS,and the drought resistance index,and thirteen co-localized SNPs between DS and the drought resistance index.These co-localized loci may be involved in the regulation of drought response in maize.GS analysis showed that when the training population proportion was 60%-70%with 20,000 markers,prediction accuracy stabilized,ranging from 0.347 to 0.483 for TL and from 0.587 to 0.609 for TBN.The prediction performance for TBN under drought stress was superior to that for TL.This study systematically eluci-dated the genetic characteristics of maize tassel structural traits under drought stress,providing an important theoretical basis for improving tassel architecture and drought tolerance in maize.