Interval mapping and meta-QTL analysis of grain traits in common wheat (Triticum aestivum L.)

Common wheat is unique in providing a large number of diverse end-products, including chapati, biscuits, bread and noodles. Grain weight and other grain traits contribute to grain yield and milling quality. Many earlier QTL studies reported at least 332 QTLs for grain traits including grain weight. We conducted a QTL analysis (composite interval mapping) of grain traits using a set of 92 recombinant inbred lines (RILs) derived from a cross between Rye Selection 111 (superior grain traits) and Chinese Spring (inferior grain traits). Forty-five QTLs for six grain traits, on 19 of the 21 chromosomes (except 2D and 3D) were identified. Nineteen of these QTLs, each for 2-3 traits were located on six chromosomes (2A, 3B, 6B, 6D, 7A and 7D). The pleiotropic nature or tight linkage of QTLs controlling different correlated traits (except the one on 6DS) was confirmed by joint MCIM. Meta-QTL (M-QTL) analysis of grain traits (including grain weight) was conducted using earlier reported QTL results (including QTLs reported in the present study). From this analysis, 23 M-QTLs were identified on eight chromosomes. These results were compared with those of our current QTL analysis and previous studies; three M-QTLs were identified as relatively more important for molecular breeding and will facilitate further work on genetic architecture and cloning of QTLs for grain traits including grain weight.