Submitted to: Genetic Resources and Crop Evolution
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/11/1996
Publication Date: N/A
Interpretive Summary: There are various species of plants closely related to sugarcane, but only the Old World relatives have been used to any extent in breeding new commercial varieties. Interestingly, there are sugarcane relatives that are native to North America. These are an untapped genetic resource for sugarcane breeding. We have a collection of sugarcane relatives from North hAmerica that have been classified by species and by chromosome number. Ou objective in this study was to compare the DNA banding patterns of five New World species, an Old World type (Erianthus), and cultivated sugarcane (also of Old World origin) to determine their level of genetic divergence. We expected to find that the New World species would be most divergent given their supposed long period of separation from their Old World relatives. Instead, the New World species and cultivated sugarcane were more closely related than was sugarcane and its Old World cousin Erianthus. .The results confirmed the validity of reclassifying the New World relative from Erianthus into the sugarcane family. Our data also indicated that the three chromosome types of one of the New World species should be reclassified as separate varieties.
Technical Abstract: Saccharum (= Erianthus) native to North America is an untapped germplasm for genetic improvement of sugarcane (Saccharum spp. hybrids). There are five species and two varieties native to North America: S. alopecuroideum, S. baldwinii, S. brevibarbe vars. brevibarbe and contortum, S. coarctatum, and S. giganteum. There are three cytotypes of S. giganteum, and they overlap in gross morphology. Our objectives were to compare genetic diversity of New World and Old World members of Saccharum. Bulked DNA for five New World species, three Old World Erianthus spp. sect. Ripidium clones, and five sugarcane cultivars was tested by PCR with 13 RAPD primers. A total of 283 repeatable RAPD bands was scored for the nine taxa. Similarity coefficients ranged from 0.365 to 0.767 indicating substantial genetic diversity among taxa. Taxa were assigned to one of three cluster groups: 1) S. baldwinii, S. brevibarbe var. contortum, S. coarctatum, and S. giganteum 2n = 90; 2) S. giganteum 2n = 30 and 2n = 60, S. alopecuroideum, and sugarcane cultivars; and 3) Old World Erianthus. Thus, sugarcane and New World Saccharum were more genetically similar than sugarcane and Old World Erianthus. The data also support the taxonomic separation of cytotypes of S. giganteum.