Cytoplasmic male sterility in sunflower: comparison of molecular biology and genetic studies.

The genetics of male fertility restoration and the RFLP of mitochondrial DNA were studied for 16 sunflower cytoplasms (15 male-sterile and a male-fertile). Male fertility restoration/male sterility maintenance patterns distinguished 12 cytotypes. Four cytoplasms were completely unrestored so they were not distinguished genetically. The sunflower lines, tested for their restorer/maintenance reaction, showed that there was a continuous range between 0% and 100% of restorer genotypes according to the CMS considered. Restoration/maintenance patterns indicated that at least some restorer genes are specific to certain CMS. RFLP of mitochondrial DNA revealed specific differences between the cytotypes studied. Three restriction enzymes and 12 probes permitted distinction of 13 cytotypes. No relationship exists between CMS cytotypes and the species from which they originated. For genetical and mitochondrial RFLP studies, phenograms were constructed according to the similarity indexes between cytotypes. Most of the CMS defined by restoration patterns correspond with a restriction fragment pattern of mitochondrial DNA.