ASSOCIATION MAPPING FOR DROUGHT TOLERANCE OF DIVERSE BREAD WHEAT GERMPLASM

Abstract

Genome-wide association studies (GWAS) were undertaken to detect SNP markers related with physiological, biochemical and yield traits in 92 genotypes from Pakistani historical set and synthetic hexaploid wheat collections. The field experiment was conducted during 2013–2015 seasons under controlled and drought conditions. Genotyping was done using high-density Illumina iSelect 15K SNP (single nucleotide polymorphism) array, and finally 7739 high quality SNPs were used in mapping. Population structure analysis identified two subpopulations (K = 2) that were representative of synthetic hexaploids and local cultivars of Pakistan. LD decay was observed at 11cM genetic distance for whole genome collection using 700 unlinked markers. In total, there were 1174 MTAs recorded for biochemical parameters at P<0.001 in stressed conditions using MLM approach, among them, 647 MTAs were flanked for more then one trait. Genome A, B and D contributed 431, 553 and 190 MTAs respectively. Highest number of MTAs were found on chromosome 2B. For yield components, out of 1035 markers, 274 were confined to a single trait. Highest number of MTAs were located on genome B (534), followed by genome A (406) and D (95). Trait wise number of MTAs were for PH(84), TGW(138), SL(106), GPS(147), DH(118), DPM(97), GL(143), PUB(89), Habit(52) and LR(61). Based upon this research, future breeding strategies can be conceived to start marker assisted breeding for manipulating favorable alleles of SNPs associated with drought related attributes to increase grain yield in stressed environments.