A haplotype block associated with thousand‐kernel weight on chromosome 5DS in common wheat ( Triticum aestivum L.)

Spike number per unit area, number of grains per spike, and thousand‐kernel weight (TKW) are important yield components for wheat ( Triticum aestivum L.). TKW has the highest heritability among the three components. We validated 27 simple sequence repeat (SSR) loci associated with TKW in an F 2:5 breeding population grown in four environments. A cfd78 265bp marker on chromosome 5DS showed the strongest association with TKW and had a significantly positive effect on TKW compared to allele cfd78 259bp , with mean increases of 5.17, 3.63, 4.11, and 5.16 g in the four environments. Markers cfd67 and cfd40 flanking cfd78 also showed significantly positive associations with TKW with increases of 5.11, 3.29, 4.31, and 4.50 g for cfd67 205 , and 4.98, 3.49, 4.06, and 4.84 g for cfd40 187 compared with cfd67 203 and cfd40 190 in the four environments, respectively. A major quantitative trait locus for TKW spanning 2.94 cM on chromosome 5DS was detected by association mapping. Strong linkage disequilibrium (LD) ( r 2  > 0.2) was detected among the three linked markers, which formed three haplotype blocks in the F 2:5 breeding population. Mean TKW differences between HapB ‐I and HapB ‐II were 5.80, 4.41, 4.02, and 5.06 g in the four environments, respectively. Moreover, significant LD was detected only between cfd78 and cfd67 and between cfd67 and cfd40 in a germplasm collection. This study provides a base for cloning genes related to TKW on chromosome 5DS.