ANALYSIS OF GENETIC-VARIABILITY OF SOUTH-AMERICAN WILD-RICE POPULATIONS (ORYZA-GLUMAEPATULA) WITH ISOZYMES AND RAPD MARKERS

The knowledge of population structure and genetic diversity of wild re latives of rice is needed to investigate their evolutionary history an d potential use in breeding programs. Very little is known about the w ild rice species (Oryza spp.), particularly those that are native to S outh America. A study using isozyme and RAPD markers was conducted to estimate the level of genetic diversity of four South American wild ri ce populations (Oryza glumaepatula) recently collected in the Amazon f orest and western Brazil rivers. F-statistics and genetic diversity pa rameters calculated from isozyme and RAPD markers indicated high value s for inbreeding coefficients and differentiation among the four popul ations. In agreement with this, a pattern of greater variation between than within populations was observed with both types of markers. Thes e findings were corroborated by an AMOVA analysis, which indicated tha t a large portion of the total genetic variation was attributed to reg ional divergence. The partition of the AMOVA analysis among population s showed that most of the genetic diversity was due to differences amo ng populations. This distribution pattern of genetic variation of O. g lumaepatula populations is in agreement with the expectation for an au togamous species and provides important baseline data for conservation and collection strategies for this species.