Genetics and the conservation and use of Australian wild relatives of crops

Genetical research stands to make crucial contributions to the in situ cons ervation of wild Australian relatives of crop plants, management of their e x situ germplasm collections, and their use in crop improvement. For instan ce, population genetic theory is basic in formulating collecting strategies . Results from the neutral allele model indicate that allelic richness in s amples from equilibrium populations is, although directly proportional to t he population size, proportional to the logarithm of the sample size. Such trends underline the importance of dividing the sampling effort among many populations. Our empirical genetical studies have been in the Australian wi ld relatives of soybean and cotton. These species not only contain signific ant genetic resources for improving their related crops, but also may be at risk from unwanted hybridisation. In perennial Glycine species, previous c ytological and genetic research detected major races within the G. tabacina polyploid complex. A maternal phylogeny on the basis of chloroplast restri ction-site variation defined plastome lineages and clarified the evolution of the polyploid complexes. Ongoing research with nuclear sequences focuses on the relationship between chloroplast and nuclear phylogenies and morpho logy. In Gossypium, estimates of interspecific hybrid fertility and outcros sing rates in natural populations near current cotton crops point to neglig ible risk of transgene escape from genetically engineered commercial cotton cultivars.