Genetic diversity among and within populations of Oryza granulata from Yunnan of China revealed by RAPD and ISSR markers: Implications for conservation of the endangered species

Abstract

In order to evaluate and preserve the endangered wild species of rice, Oryza granulata, we investigated the existing population distribution in Yunnan Province of Southwestern China. The genetic diversity among 14 populations (bulk samples) and within two populations (individual samples) was studied using random amplified polymorphic DNA (RAPD) and inter-simple sequence repeat (ISSR) amplification markers. The field survey showed that 44% natural populations of O. granulata in Yunnan have become extinct during the last 30 years. Of the 37 remaining wild populations, 28 (76%) are on the verge of extinction and nine (24%) were unaffected. For the study among the 14 populations, the percentage of polymorphic bands (PPB) was 59% for RAPDs and 64% for ISSRs. However, within populations, the PPB generated by RAPDs and ISSRs was 26 and 26% in the first population (S1) and similarly within the second population (S2) (21 and 22%, respectively). The results showed that genetic variation is much higher among populations of O. granulata than within populations. Analyses of Nei's gene diversity, unbiased genetic distance and Shannon's index also agreed with these results. Therefore, we proposed an appropriate strategy for conserving the genetic resources of O. granulata in Yunnan; namely, rescuing and conserving the core populations for in situ conservation, and sampling and preserving more populations with fewer individuals from each population for ex situ conservation. © 2004 Elsevier Ireland Ltd. All rights reserved.