QTL Analysis and Gene Expression Studies in White Clover

Abstract

In white clover (Trifolium repens L.) plant persistence, overwintering and grazing tolerance are to a significant extent determined by the presence of a dense network of horizontal stems or stolons. At IGER, we have developed new linkage maps of white clover specifically to facilitate the identification of quantitative trait loci (QTLs) for important components of stolon morphology. The parents of the F₁ mapping family were derived following two generations of divergent selection for stolon traits, in particular length and thickness. One parental genotype had thick, sparse stolons and one parent had thin profuse stolons. Two linkage maps were generated for each parental clone: one consisted of 16 linkage groups with 154 markers covering 710 cM and the other consisted 13 linkage groups with 86 markers covering 524 cM. There are 31 shared markers across the two maps. A total of nine QTLs were identified on the maps for the following traits: stolon width, internode length, petiole length, leaf length and width, plant spread and height. Potential QTLs associated with water use efficiency (WUE) have also been identified.