Abstract:

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 cfd67₂₀₅, and 4.98, 3.49, 4.06, and 4.84 g for cfd40₁₈₇ compared with cfd67₂₀₃ and cfd40₁₉₀ 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) (r² > 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.

Wang Y, Hao C, Zheng J, Ge H, Zhou Y, Ma Z, Zhang X (2015) A haplotype block associated with thousand-kernel weight on chromosome 5DS in common wheat (Triticum aestivum L.). J Integr Plant Biol 57: 662–672. doi: 10.1111/jipb.12294

Key words: Association mapping, haplotype, thousand-kernel weight, Triticum aestivum