Pastoral Genomics - a foray into the clover genome

Abstract

Pastoral Genomics is engaged in applying molecular mapping and functional genomics to characterise and manipulate key phenotypic traits associated with improved productivity in the commercially important forage crop white clover (Trifolium repens L.). We report on the development of a framework linkage map for white clover and the application of this map to the identification of quantitative trait loci (QTL) associated with vegetative and seed yield traits. Homologues of genes responsible for the traits of interest have been identified and cloned in order to identify 'perfect markers' for marker assisted breeding and to develop a cisgenic® clover cultivar. We introduce western clover (T. occidentale), a diploid perennial clover species closely related to white clover, as a stoloniferous clover model to dissect low heritability traits initially intractable in white clover. We have identified extensive genetic variation in this species, which previously has been reported to be remarkably uniform. We have developed a framework map for T. occidentale and demonstrated conservation of marker order and spacing with white clover. An ethyl methane sulfonate (EMS) mutant population has been used to isolate three distinct groups of condensed tannin (CT) mutants. We have also investigated our model's transformation potential, achieving frequencies 2-3 fold higher than for white clover and suggest that this model is potentially useful for genomic analysis of white clover and other clonal species