Further data on the genomic relationships among wild perennial species (2n = 40) of the genus Glycine Willd.

Abstract

The present study furnishes information about the current status of knowledge concerning the genomic relationships among 9 of the 12 wild perennial species (2n = 40) of the subgenus Glycine. Crossability rate, hybrid inviability, and meiotic pairing in intra- and inter-specific F1 hybrids revealed that genomically similar species, though morphologically distinct, crossed readily to produce hybrid progeny that were vigorous, fertile, and normal in meiotic pairing (20 bivalents at metaphase I). However, a chromatin bridge and acentric fragment were recorded in certain hybrid combinations, suggesting that the evolutionary divergence in genomically similar species occurred because of paracentric inversions. In contrast, crosses between genomically dissimilar species set pods that often aborted, showed hybrid weakness, seedling and vegetative lethality, seed inviability, and complete sterility. The sterility was attributed to disturbed meiotic pairing. It is obvious from this study that A-genome species such as G. canescens (AA) G. clandestina (intermediate pod, A1A1, and long pod, A2A2), and G. argyrea (A3A3), and B-genome species such as G. microphylla (BB), G. latifolia (B1B1), and G. tabacina (B2B2) predominate in the subgenus Glycine. Glycine cyrtoloba (CC) showed stronger genome homology to B-genome species than to A-genome species. Likewise, G. tomentella (DD) appeared to be more closely associated with A-genome species than to B-genome species. Although tomentellas with 38 and 40 chromosomes were indistinguishable morphologically, they differed genomically. Therefore, genome symbol EE was assigned to the 38-chromosome G. tomentella. Glycine falcata (FF) was found to be the most unusual species because it showed negligible chromosome homology with A- and B-genome species and did not set pods when cross-pollinated by C-, D-, and E-genome species.Key words: Glycine spp., genome, hybridization.