RELATIONSHIPS AMONG ANCESTRAL SPECIES OF SUGARCANE REVEALED WITH RFLPUSING SINGLE-COPY MAIZE NUCLEAR PROBES

DNA restriction fragment length polymorphism (RFLP) analysis was perfo rmed on 50 wild and old cultivated sugarcane accessions. Ninety-four m aize low copy nuclear DNA sequences of known chromosomal position were screened for hybridization to digested sugarcane genomic DNA blots. S eventy-five (80%) gave very strong hybridization signals and usually y ielded many bands and detected profuse polymorphism. Twenty-nine probe s and 36 probe/enzyme combinations were selected on the basis of the s corability of the banding profiles. A total of 1110 fragments were sep arately identified among the 50 genotypes. Multivariate analyses of th e data allowed the separation of the three basic species, Saccharum sp ontaneum, S. robustum and S. officinarum, showed that S. spontaneum ha d structure which could be related to the geographic origin of the clo nes and supported current hypotheses on the origin of secondary specie s S. barberi and S. sinense. The use of more probes did not improve th e resolution between the various species examined but identified a few key polymorphisms which were not accounted for by current phylogeneti c hypotheses and can guide future analyses. RFLPs in sugarcane will be useful essentially for depicting the genomic constitution of modern v arieties of interspecific origin.