MOLECULAR CHARACTERIZATION OF FERTILE AND STERILE CYTOPLASMS IN BETA SPP

Mitochondrial DNA (mtDNA) from sugar beet carrying fertile (F) and mal e sterile (CMS) cytoplasms, and from male sterile accession of Bera ma ritima collected in Brittany (France) were characterized and compared by restriction fragment length polymorphism (RFLP) and Southern hybrid ization with coxII. The F and CMS cytoplasms could be clearly distingu ished from each other by RFLP when XhoI, EcoRI and BrunHI endonuclease s were used. Southern hybridization with the coxII gene provided furth er evidence that mitochondrial genome organization differs between fer tile and sterile plants. All cytoplasmic male sterile lines from diffe rent breeding stations showed the same restriction and hybridization p atterns, which confirms the uniformity of mitochondrial genomes within the materials used for hybrid seed production in several European cou ntries. No visible differences were found between the maintainer lines studied. However, comparisons of XhoI restriction profiles of mtDNA f rom maintainer lines and from fertile monogerm populations revealed sl ight differences, which were reflected by the appearance of a unique 0 .9 kb fragment in the latter. Analysis of mtDNA from male sterile plan ts of the wild beet B. maritima showed different restriction and hybri dization patterns in comparison with normal and sterile sugar beet cyt oplasms. This shows the unique nature of cytoplasmic male sterility in this species.