Submitted to: American Society for Horticultural Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 2, 1996
Publication Date: N/A
Interpretive Summary: The cole crop family includes many important vegetables such as broccoli, cabbage, and cauliflower. Also in this family is collard, a major leafy-green crop grown extensively in southern states. Unlike broccoli and cauliflower, which were brought to America in this century, collard greens have been grown in the South for several hundred years. Surprisingly, little is known about collard and its relationship to other cole crops. This research was undertaken to gain a better understanding of collard and its place in the cole crop family. Using modern DNA fingerprinting techniques, it was shown that collard is a distinct member of the cole crop family, but is most closely related to cabbage. In addition, results indicated that collard has unique genetic characters not found in other cole crops. This information provides evidence that collard may prove to be a source of new and useful genes for improving varieties of cole crops. With this knowledge public and private breeders can more efficiently breed improved varieties of collard and the other cole crops as well.
Technical Abstract: Collard (Brassica oleracea L. Acephala group) germplasm including 13 cultivars or breeding lines and 5 landraces, was evaluated using random amplified polymorphic DNA (RAPD) markers and compared to representatives of kale (Acephala group), cabbage (Captitata group), broccoli (Italica group), Brussels sprouts (Gemmifera group), and cauliflower (Botrytis group). Objectives were to assess genetic variation and relationships among collar and other crop entries, evaluate intrapopulation variation of open- pollinated (OP) collard lines, and determine if collard landraces might provide new B. oleracea genes. RAPD bands (316) were scored from 18 oligonucleotide decamer primers when collard and other crop entries were compared. Of these bands, 224 (70%) were polymorphic and 31 were specific to collard. Similarity indices between collard entries computed from RAPD data ranged from 0.76 to 0.98 with an average of 0.83. Collard entries were eclosely related to cabbage (similarity index = 0.80) and Brussels sprouts entries (index = 0.78). Analysis of individuals of an OP cultivar and landrace indicated that intrapopulation genetic variation is as great as that observed between populations. RAPD analysis indicated collard landraces are unique genotypes and sources of unique DNA markers. Collection of collard landraces should enhance diversity of the B. oleracea germplasm pool and provide genes for future crop improvement.