Organelle assortment and mitochondrial DNA rearrangements in Brassica somatic hybrids and cybrids

Protoplast fusion permits manipulations of organelle genomes not readily achieved by other in vitro procedures or sexual crosses. Although considerable information is now available about the fate of chloroplasts and mitochondria in fusion products of various genera, many additional questions about factors affecting organelles after fusion remain to be answered. Brassica species are particularly favorable materials for such studies. Organelle assortment, mitochondrial DNA (mtDNA) recombination, and plant phenotypes observed after fusion of protoplasts from cytoplasmic male sterile B. oleracea with protoplasts from B. campestris, B. oleracea or B. napus are described. The somatic hybrids and cybrids obtained at Cornell have been used for detailed studies of recombinant mtDNA, including correlation of a specific mtDNA region with the ogura type of cytoplasmic male sterility, and have provided plant materials for possible use in hybrid breeding programs.