molecular biology of plant mitochondria

This is a study of advances in molecular biology and cell-culture techniques which have given impetus to investigations of plant mitochondria. The organization of mitochondrial genomes has been intensely studied in maize, wheat, Oenothera, petunia, Brassica, and a few other species. These investigations have disclosed an unusually large and plastic genome, a unique organization based on a master chromosome and subgenomic chromosomes, and extra mitochondrial elements. The structural RNAs of plant mitochondria have furnished several discoveries, including the import of tRNAs into the mitochondria, editing of mRNAs, and the "relaxed" nature of mitochondrial gene promoters. Cytoplasmic male sterility (CMS) is the most common mitochondrial gene mutation, and has therefore received extraordinary attention. Several mitochondrial gene mutations have been implicated in causing CMS, and attention is now focusing on the mechanism that causes pollen sterility, and how nuclear restorer genes interact with CMS genes to suppress sterility.