Polyploid complexes of Glycine tabacina (Labill.) Benth. and G. tomentella Hayata revealed by cytogenetic analysis

Observations on geographical distribution, cytotypes, crossability, and meiotic chromosome behavior in intra- and interspecific F1 hybrids revealed that the complexes of Glycine tabacina (2n = 40, 80) and G. tomentella (2n = 38, 40, 78, 80) evolved through allopolyploidization. It is apparent from this study that 80-chromosome tabacinas are composed of two distinct morphological complexes having one common genome: with and without adventitious roots. In contrast, the tomentellas are inseparable morphologically. They are composed of accessions with at least three genomic complexes: (i) 2n = 80, accessions from Australia and Taiwan; (ii) 2n = 80, an accession from Papua New Guinea; and (iii) 2n = 78, accessions from Australia and Papua New Guinea. Hybrids within each group showed complete synapsis and set normal seeds; however, hybrids between the groups apparently differed by one genome and were completely sterile. Chromosome pairing in triploid interspecific F1 hybrids (2n = 59, 60) indicated that G. canescens (2n = 40) was probably the donor of the common genome for 80-chromosome tabacinas and tomentellas. Glycine latifolia (2n = 40) appears to have contributed its genome to G. tabacina (2n = 80) but could not have participated in the speciation of 80-chromosome tomentellas. Likewise, the 38-chromosome G. tomentella has no genomic affinity with 80-chromosome tabacinas but has complete affinity with 80-chromosome tomentellas. On the basis of present findings and the results published earlier, the evolution of the genus Glycine will be discussed. Key words: Glycine spp., genome, hybridization (intraspecific), hybridization (interspecific), speciation.