Breaks of macrosynteny and collinearity among moth bean (Vigna aconitifolia), cowpea (V. unguiculata), and common bean (Phaseolus vulgaris)

摘要

Comparative cytogenetic mapping is a powerful approach to gain insights into genome organization of orphan crops, lacking a whole sequenced genome. To investigate the cytogenomic evolution of importantVignaandPhaseolusbeans, we built a BAC-FISH (fluorescent in situ hybridization of bacterial artificial chromosome) map ofVigna aconitifolia(Vac, subgenusCeratotropis), species with no sequenced genome, and compared withV. unguiculata(Vu, subgenusVigna) andPhaseolus vulgaris(Pv) maps. SeventeenPvBACs, eightVuBACs, and 5S and 35S rDNA probes were hybridized in situ on the 11Vacchromosome pairs. FiveVacchromosomes (Vac6,Vac7,Vac9,Vac10, andVac11) showed conserved macrosynteny and collinearity betweenV. unguiculataandP. vulgaris. On the other hand, we observed collinearity breaks, identified by pericentric inversions involvingVac2 (Vu2),Vac4 (Vu4), andVac3 (Pv3). We also detected macrosynteny breaks of translocation type involving chromosomes 1 and 8 ofV. aconitifoliaandP. vulgaris; 2 and 3 ofV. aconitifoliaandP. vulgaris; and 1 and 5 ofV. aconitifoliaandV. unguiculata. Considering our data and previous BAC-FISH studies, six chromosomes (1, 2, 3, 4, 5, and 8) are involved in major karyotype divergences between genera and five (1, 2, 3, 4, and 5) betweenVignasubgenera, including mechanisms such as duplications, inversions, and translocations. Macrosynteny breaks betweenVignaandPhaseolussuggest that the major chromosomal rearrangements have occurred within theVignaclade. Our cytogenomic comparisons bring new light on the degree of shared macrosynteny and mechanisms of karyotype diversification duringVignaandPhaseolusevolution.