Genetic Analysis of Kernel Uniformity and Thousand‐Kernel Weight in Modern Wheat (Triticum aestivum L.) Using GWAS

ABSTRACT Kernel uniformity (KU) plays an essential role in the appearance and milling quality, as well as plant growth and development evenness, and even yield stability in wheat ( Triticum aestivum L.). However, the underlying connection between KU and thousand‐kernel weight (TKW) remains poorly understood. In this study, KU was calculated and evaluated by the coefficient of variation of kernel length, width, perimeter and area from 149 diverse modern wheat genotypes using the affiliation function method, which was found to be a weak negative correlation ( R 2 = −0.38) with TKW. A genome‐wide association study was performed using the Wheat 55K SNP array to dissect the genetic architecture underlying KU and TKW, with the aim of facilitating integrated genetic selection. A total of four marker‐trait associations (MTAs) ( p < 0.001) were identified for KU on chromosomes 2A (2), 2D and 7A, and four MTAs for TKW on chromosomes 1B, 4A, 4B and 5B, explaining 7.80%–10.35% and 8.16%–11.41% of the phenotypic variations, respectively. Among them, one stable MTA for KU ( KU‐2A.2 ) and two for TKW ( TKW‐4A and TKW‐4B ) were identified, each containing more than three associated SNPs within the linkage disequilibrium (LD) decay distance. Haplotype analysis showed that HapKU‐2A.2‐III , HapTKW‐4A‐IV and HapTKW‐4B‐III were the superior haplotypes. Notably, only four elite genotypes—Bainong 64, Fanmai 5, Huaimai 44 and Wankenmai 0622—simultaneously carried favourable haplotypes associated with both improved KU and increased TKW. The study can provide valuable genetic information for modern wheat improvement.