PHYLOGENETIC-RELATIONSHIPS AMONG FERTILE AND PETALOID MALE-STERILE ACCESSIONS OF CARROT, DAUCUS-CAROTA L

Mitochondrial (mt) DNA variation for six petaloid cytoplasmic male-ste rile (CMS) and three fertile maintainer lines of carrot was assessed t o establish genetic relationships. Total DNA was digested with restric tion enzymes and probed with six homologous mtDNA cosmid probes. The s ix CMS accessions derived from wild carrot, four from Guelph, Ontario, one from Orleans, Massachusetts, and one from Madison, Wisconsin? wer e more closely related with each other (F = 0.91) than with fertile ma intainer lines derived from cultivated germplasm (F = 0.62). The ferti le maintainer lines were likewise found to be more similar to each oth er (F = 0.78) than to the sterile lines. Three sterile lines, originat ing from wild carrot populations within 1 km of each other in Guelph, Ontario, were most closely related (F = 0.96). The high degree of simi larity among the six petaloid CMS lines which originated from individu al wild carrot plants, some from geographically diverse regions, sugge sts that the cytoplasm responsible for this trait was imported to, or else evolved, only once in North America.