Genome-wide association mapping for stay-green and stem reserve mobilization traits in wheat (Triticum aestivum L.) under combined heat and drought stress.

Stay-green (SG) and stem reserve mobilization (SRM) are two significant mutually exclusive traits, which contributes to grain-filling during drought and heat stress in wheat. The current research was conducted in a genome-wide association study (GWAS) panel consisting of 278 wheat genotypes of advanced breeding lines to find the markers linked with SG and SRM traits and also to screen the superior genotypes. SG and SRM traits, viz. soil plant analysis development (SPAD) value, canopy temperature (CT), normalized difference vegetation index (NDVI), leaf senescence rate (LSR) and stem reserve mobilization efficiency (SRE) were recorded. The trial was conducted in α-lattice design, under control and combined heat and drought stress (HD). Analysis of variance and descriptive statistics showed a significant difference across the evaluated traits. The highest mean of SRE (31.7%) and SRM (0.42 g/stem) was reported in HD, while highest SRE in HD and lowest in control was 52.56% and 15.7%, respectively. Genotyping was carried out using the 35 K Axiom R Wheat Breeder's Array, 14,625 SNPs were kept after filtering. Through GWAS, 36 significant marker trait associations (MTAs) were identified on 16 distinct chromosomes; out of this, 22 MTAs were found under control and 14 MTAs under HD. Candidate genes that code for UDP-glycosyltransferase 73C4-like and protein detoxification 40-like was linked to SPAD and CT respectively. One MTAs was detected for SRM on chromosome 6B that code for wall associated receptor kinase 4 like. These SNPs can be utilized to generate cultivars that adapt to climate change by a marker-assisted gene transfer.