Molecular aspects of cytoplasmic male sterility in perennial ryegrass (Lolium perenne L.): mtDNA and RNA differences between plants with male-sterile and fertile cytoplasm and restriction mapping of their atp6 and coxI homologous regions.

Lolium perenne L. male-sterile and fertile cytoplasms contain different mitochondrial genomes, as revealed by Southern hybridization with a number of heterologous mitochondrial probes. In addition, transcriptional patterns of atp6 and coxI genes distinguish both cytoplasmic types. The majority of the L. perenne sequences from male-sterile and fertile cytoplasm showing homology with these two genes has been cloned and mapped by restriction digestion. A complex genomic organization, especially concerning coxI homologous sequences, was found in the male-sterile cytoplasm. Furthermore, during the course of these studies tissue-culture-induced mtDNA mutations in a number of coxI-containing sequences were detected in regenerated plants.