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

Abstract

Genetical research stands to make crucial contributions to the in situ conservation of wild Australian relatives of crop plants, management of their ex situ germplasm collections, and their use in crop improvement. For instance, population genetic theory is basic in formulating collecting strategies. Results from the neutral allele model indicate that allelic richness in samples from equilibrium populations is, although directly proportional to the 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 wild relatives of soybean and cotton. These species not only contain significant genetic resources for improving their related crops, but also may be at risk from unwanted hybridisation. In perennial Glycine species, previous cytological and genetic research detected major races within the G. tabacina polyploid complex. A maternal phylogeny on the basis of chloroplast restriction-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 morphology. In Gossypium, estimates of interspecific hybrid fertility and outcrossing rates in natural populations near current cotton crops point to negligible risk of transgene escape from genetically engineered commercial cotton cultivars.