Interspecific hybridization between cultivated american species of the genusphaseolus

Summary Attempted interspecific hybridization between the speciesPhaseolus vulgaris, P. coccineus, P. acutifolius andP. lunatus has indicated that a close genetic relationship exists betweenP. vulgaris andP. coccineus. Viable hybrids of varying fertility can be made reciprocally between these species. Affinity is indicated withP. acutifolius by the formation of viable but sterile hybrids. Less affinity is apparent between these three species andP. lunatus with which they do not produce viable interspecific hybrids. Nevertheless morphological resemblances between the four species justify their retention within the same section of the genus.Effects of cytoplasmic constitution on both fertility and viability were shown in the F₂ and backcross progenies ofP. vulgaris () ×P. coccineus () hybrids and on viability in theP. vulgaris () ×P. acutifolius () and reciprocal hybrids. In slightly fertileP. vulgaris () ×P. coccineus () hybrids it was concluded that distorted F₂ segregations were due to differential loss ofP. coccineus genes in sporogenesis and embryogenesis occurring in aP. vulgaris plasmon.Formerly at The School of Agriculture, University of Cambridge.