A novel QTL discovered for grain protein content without grain weight penalty in wheat (Triticum aestivum L.)

Wheat (Triticum aestivum L.) is a global food crop with a relatively low protein content of 9-12%. Enhancing grain protein content (GPC) without compromising grain yield remains a challenge due to the negative correlation between yield and GPC. However, recent advances in genome-wide DNA markers, high-throughput phenotyping, genome-wide association studies (GWAS), and quantitative trait loci (QTL) mapping have facilitated the identification of important QTLs. This study utilized a stable recombinant inbred line (RIL) F_7 - 9 population, genotyped using high-depth genotyping-by-sequencing (GBS), and phenotyped across multi-environmental field trials to identify stable QTLs for GPC. In contrast to the often-reported negative correlation between GPC and Thousand Grain Weight (TGW), the RIL population exhibited a significant positive correlation of 0.143 (p < 0.001) between the two traits. Significant genetic variation in GPC was observed in the population, with a heritability of 0.72, indicating a strong genetic influence. Further genetic analysis revealed the presence of ten QTLs responsible for GPC variation, located on chromosomes 1D, 2B, 4B, 5 A, and 5B. Among these, QGPC.nabi-2B.2 and QGPC.nabi-5B.1 were identified in more than three environments as major QTLs. Precise mapping of QGPC.nabi-2B.2, using indigenously designed SSRs, identified potential candidate genes involved in GPC regulation. Three SNPs from this region were converted into Tetra-ARMS-PCR markers and validated in Indian wheat varieties and a genetically different RIL population. This study provides a foundation for future research into the genetic regulation of GPC in wheat, suggesting key candidate genes that could improve wheat's nutritional quality without compromising grain weight.

The online version contains supplementary material available at 10.1007/s12298-026-01707-5.