A UNIQUE CYTOPLASMIC MALE-STERILITY (CMS) DETERMINANT IS PRESENT IN 3PHASEOLUS SPECIES CHARACTERIZED BY DIFFERENT MITOCHONDRIAL GENOMES

Previous results have shown that cytoplasmic male sterility (CMS) in l ines from Phaseolus coccineus and Phaseolus vulgaris contain the same CMS-specific sequence, raising the question of whether this sequence r earrangement arose before divergence of the two species or afterward w ith subsequent transfer by introgression. Hybridization patterns of to tal DNA from eight P. vulgar is lines with cytoplasm from P. coccineus and three P. vulgaris lines were examined in order to analyze the mit ochondrial DNA (mtDNA) diversity within each species and to determine differences between CMS lines derived from the two species. Three rest riction enzymes and 17 heterologous mtDNA sequences were used. The ana lysis of the different hybridization patterns revealed a considerable diversity in mtDNA organization particularly within P. coccineus. We o btained distinctive hybridization patterns for the five CMS lines test ed. The resulting classification showed that mitochondrial genomes fro m P. coccineus CMS lines group with those of fertile P. coccineus but not with CMS lines from P. vulgaris. The groupings concur with the tax onomic classification of these lines. The results support the hypothes is of a single ancient origin of the CMS determinant and exclude the t ransfer of cytoplasm by introgression from P. vulgaris to P. coccineus and P. coccineus ssp polyanthus.