Genomic diversity and multiple origins of tetraploid (2n = 78, 80) Glycine tomentella.

Among 15 wild perennial species of the genus Glycine Willd. subgenus Glycine, G. tomentella is exceptional. It is composed of four cytotypes (2n = 38, 40, 78, 80), is diverse in morphological features, and covers a wide geographical area. The objectives of this study were to uncover the genomic diversity in 78- and 80-chromosome cytotypes through a multidisciplinary approach, using cytogenetic, biochemical, and molecular methods, to verify previously identified isozyme groupings and to determine their possible origins. The cytogenetic observations, total seed protein and protease inhibitor profile comparisons, and the phylogenetic analysis of restriction fragment length polymorphisms identified three distinct groups (T1, T5, T6) among aneutetraploid (2n = 78) and four distinct groups (T2, T3, T4, T7) among tetraploid (2n = 80) G. tomentella accessions. The groupings were congruent with those of isozyme analysis. Tetraploid accessions from Indonesia were assigned to a new group, T7, based on the present study. Morphology, cytology, and seed protein banding patterns of synthetic tetraploids indicated that the T1 and T5 group aneutetraploids were composed of D3D3EE and AAEE genomes, respectively, and the T2 group tetraploid accessions consisted of AAD3D3 genomes. Various groups within the 78- and 80-chromosome G. tomentella were suggested to have originated in Australia by allopolyploidization, most likely through multiple independent events.