Cytological and Isozyme Diversity in Glycine tomentella Hayata (Leguminosae)

Abstract

A collection of 11 5 accessions of Glycine tomentella from New South Wales, Queensland, Papua New Guinea and Taiwan was surveyed for isozyme variation in 10 enzyme systems. The most polymorphic system was glucosephosphate isomerase (GPI) with 30 distinct phenotypes. Some GPI phenotypes were widespread geographically and included both aneuploid and euploid tetraploids. Taken as a group, zymograms were predictive of ploidy level (i.e. diploid or tetraploid) but were not reliable predictors of aneuploidy (2n = 38, 78) or euploidy (2n = 40, 80). The somatic chromosome numbers of about half the accessions were determined. The frequency of the diploids was greater than expected on morphological grounds and both diploid and tetraploid forms were widely distributed geographically. The aneuploid forms at both levels of ploidy had a more southerly distribution than the euploid forms. The species was found to be highly diverse for isozymes and chromosome number. Crosses between several of the tetraploid accessions were made and the meiotic configurations determined. Sterile hybrids were obtained from the majority of interregional crosses but in some exceptional crosses the intraregional hybrids were sterile and the interregional crosses were fertile. In all cases sterile hybrids apparently shared two of their four primitive genomes. The degree of cytological affinity of the genomes as measured by the genome affinity index was positively related to their degree of isozyme similarity.