Identification of RFLP markers linked with heading date and its heterosis in hexaploid wheat

Recombinant inbred lines (RILs) from a cross between hexaploid wheat (T. aestivum cv. Chinese Spring (CS) and T. spelta (Sp)) were used for RFLP analysis of heading date and heterosis. Fourteen RFLP markers linking with heading date were identified; two were localized on chromosome 1A, one on 2A, three on 2B, one on 2D, four on 5A, two on 7A and one unlinked but reported to be on group 2. All of these markers may be attributable to genes for earliness par sc. However, the markers in the chromosomes of 1A and 7A are new to this study. RILs were crossed with (tim)-CS, the alloplasmic CS with T. timopheevi cytoplasm, and the heterosis from earlier-parent and mid-parents were calculated for the F(1)s to examine the heterotic effect toward earliness on heading date. Five and two RFLP markers were associated with heterosis from the earlier-parent and mid-parents, respectively. They were distributed on the chromosomes of homoeologous groups 1 and 2.