Genetic identification and characterization of a novel locus for wheat kernel length

Kernel length (KL) is one of the components that determine grain weight (GW) in wheat. In this study, a putative locus on chromosome arm 2BL was identified from mutant BLS2 with long kernels using a bulked segregant analysis (BSA) combined with a 60K SNP array. This putative locus was then confirmed as a major and stable QTL based on linkage mapping. The locus, Qkl.sau-BC-2B.1, was mapped in an interval of 0.4 cM, and the phenotypic variance explained by it varied from 17.01 to 30.53% across different environments. The effects of this locus were further verified in a second population. The positive allele of the locus could significantly increase hundred-kernel weight and prolong the anthesis date, but it did not affect plant height, tiller number, spike length, or spikelet number per spike. Expression and sequencing analyses identified TraesCS2B02G478100, which has a G to C transition variation leading to an amino acid change, as the likely candidate gene underlying this locus. In addition, a new model for analyzing the genetic basis of yield-related traits is proposed. Taken together, our results provide a foundation for subsequent gene mining and the use of this promising QTL in breeding for KL.