Unlocking the genetic control of spring wheat kernel traits under normal and heavy metals stress conditions

Background and aims Pb and Sn concentration increase rapidly due to the industrial revolution and cause a significant reduction in wheat production and productivity. Understanding the genetic control of Pb and Sn tolerance is very important to produce wheat cultivars that are tolerant to such metals. Methods Extensive genetic analyses using genome-wide association study, functional annotation, and gene enrichment were investigated in a set of 103 highly diverse spring wheat genotypes. Kernel traits such as kernel length (KL), kernel diameter (KD), kernel width (KW), and 1000-kernel weight (TKW) were measured under each metal as well as under controlled conditions. Results The GWAS identified a total of 131, 126, and 115 markers that were associated with kernel traits under Ctrl, Pb, and Sn. Moreover, the stress tolerance index (STI) for Pb and Sn was calculated and GWAS revealed 153 and 105 significant markers, respectively. Remarkably, one SNP Ku_c269_2643 located within TraesCS2A02G080700 gene model was found to be associated with KL under the three conditions. The results of gene enrichment revealed three, three, and six gene networks that have an association with the processes involved in kernel formation. The target alleles of all significant markers detected by GWAS were investigated in the most tolerant wheat genotypes to truly select the candidate parents for crossing in future breeding programs. Conclusion This is the first study that unlocked the genetic control of kernel yield under controlled and heavy metals conditions. Understanding the genetic control of kernel traits under heavy metals will accelerate breeding programs to improve wheat tolerance to Pb and Sn.