Variation in allelic frequencies at loci associated with kernel weight and their effects on kernel weight-related traits in winter wheat

Abstract Knowledge of allelic frequencies at loci associated with kernel weight and effects on kernel weight-related traits is crucial for yield improvement in wheat. Kernel weight-related traits were evaluated in 200 Chinese winter wheat cultivars (lines) grown at the Xinxiang Experimental Station, Chinese Academy of Agricultural Sciences , Xinxiang in Henan Province, for three consecutive years from 2014 to 2016. Alleles associated with kernel weight at nine loci, TaCKX6-D1 , TaCwi-A1 , TaCWI-4A , TaGS1a , TaGS5-A1 , TaGS3-3A , TaGW2-6A , TaSus2-2B , and TaTGW6-A1 , were determined for all cultivars (lines). ANOVA showed that genotypes, years and their interactions had significant effects on thousand-kernel weight (TKW), kernel length (KL) and kernel width (KW). The overall mean frequencies of alleles conferring high and low TKW at the nine loci were 65.9% and 33.4%, with the ranges of 37.0%–85.0% and 13.5%–63.0% for single loci. The frequencies of high-TKW alleles were over 50.0% at eight of the loci. Genotypes at each locus with the high-TKW allele had higher TKW than those with the low-TKW allele. The high-TKW allele Hap-H at the TaSus2-2B locus can be preferably used to increase grain yield due to its high TKW (49.32 g). A total of 18 main allelic combinations (ACs) at nine loci were detected. Three ACs (AC1–AC3) had significantly higher TKW than AC6 with high-TKW alleles at all nine loci even though they contained some low-TKW alleles. This indicated that other loci controlling kernel weight were present in the high-TKW cultivars. This work provides important information for parental selection and marker-assisted selection for breeding.