The cytoplasmic male-sterility (CMS) determinant of common bean is widespread in Phaseolus coccineus L. and Phaseolus vulgaris L.

To identify regions of the mitochondrial genome that potentially could specify cytoplasmic male sterility (CMS) in Phaseolus coccineus (including P. polyanthus), and to define differences amongst P. coccineus lines, mitochondrial (mt)DNA restriction patterns and Southern blots of total DNA from sterile and fertile lines were analysed. By restriction endonuclease mapping we isolated a region which was specific to CMS lines flanking an F1-ATPase alpha-subunit (atpA) gene. DNA sequence analysis of this region showed 99.9% homology to the region previously isolated from P. vulgaris CMS Sprite. A high frequency of plants carrying the CMS-fragment was observed in a wild Phaseolus population, perhaps explaining the occurrence of inter- and intra-specific gene flow observed in the autogamous species P. vulgaris.