MOLECULAR MARKERS LINKED TO GENES AFFECTING PLANT HEIGHT IN WHEAT USING A DOUBLED-HAPLOID POPULATION

Plant height in wheat (Triticum aestivum L. em Thell) is known to be u nder polygenic control. Crosses involving genes Rht-B1 and Rht-D1, loc ated on chromosomes 4BS and 4DS, respectively, have shown that these g enes have major effects. Two RFLP loci were found to be linked to thes e two genes (Xfbal-4B with Rht-B1 and Xfba211-4D with Rht-D1) by genot yping a population of F-1-derived doubled-haploid lines ['Courtot' (Rh t-B1b + Rht-D1b) x 'Chinese Spring']. Using a well-covered molecular m arker map, we detected three additional regions and one interaction in fluencing plant height. These regions, located on chromosome arms 4BS (near the locus Xglk556-4B), 7AL (near the locus Xglk478-7A) and 7BL ( near the locus XksuD2-7B) explained between 5% and 20% of the variabil ity for this trait in this cross. The influence of 2 loci from chromos ome 4B (Xfbal-4B and Xglk556-4B) suggests that there could be a duplic ation of Rht-B1 on this chromosome originating from Cv 'Courtot'. More over, an interaction effect between loci from chromosome arms 1AS (nea r the locus Xfba393-1A) and 1BL (near the locus Xcdo1188-1B) was compa rable to or even higher than those of the Rht-B1b and Rht-D1b alleles. A model including the main effects of the loci from chromosomes 4B an d 4D (Xfbal-4B, Xglk556-4B and Xfba211-4D) and the interaction effect between Xfba393-1A and Xcdo1188-1B is proposed, which explains about 5 0% of the variation inplant height. The present results are discussed in relation to those obtained using nullisomic or substitution lines.