Unlocking the grain quality enigma: A KASP-driven voyage through bread wheat's quantitative trait nucleotides under heat adversity

Heat stress is a critical factor affecting global wheat production and
productivity. In this study, out of 500 studied accessions a diverse panel
of 126 wheat genotypes grown under twelve distinct environmental
conditions was analyzed. Using 35K single-nucleotide polymorphism (SNP)
genotyping assays and trait data on five biochemical parameters, including
grain protein content (GPC), grain amylose content (GAC), grain total
soluble sugars (TSS), grain iron (Fe), and zinc (Zn) content, six
multi-locus GWAS models were employed for association analysis. This
revealed 67 significantly associated QTNs linked to grain quality
parameters, explaining phenotypic variations ranging from 3% to 44% under
heat stress conditions. By considering the results in consensus to at
least three GWAS models and three locations, the final QTNs were reduced
to 17, with 14 being novel findings. Notably, two novel markers,
AX-94461119 (chromosome 6A) and AX-95220192 (chromosome 7D), associated
with grain iron and zinc, respectively, were validated through KASP
approach. Candidate genes, such as chaperonin Cpn60/GroEL/TCP-1 family,
P-loop containing nucleoside triphosphate hydrolases (NTPases),
Bowman-Birk type proteinase inhibitor (BBI), and NPSN13 protein, were
identified from the associated genomic regions, which could be potentially
targeted for improving quality traits and heat tolerance in wheat.