COMPARATIVE-EVALUATION OF WITHIN-CULTIVAR VARIATION OF RICE (ORYZA-SATIVA L) USING MICROSATELLITE AND RFLP MARKERS

The objective of this study was to determine an efficient way of detec ting within-cultivar variation in rice varieties obtained from nationa l and international germplasm collections, Seventy-one rice cultivars were evaluated for within-cultivar variation using a combination of ph enotypic, RFLP, and mitrosatellite or simple sequence length polymorph ism (SSLP). Variation between individuals within an accession and betw een duplicate accessions within a cultivar was detected even in cultiv ars that had been purified by phenotypic evaluation. Landrace cultivar s were more heterogeneous and displayed a larger number of both RFLP a nd SSLP alleles than did modem cultivars. Microsatellite markers detec ted a greater number of alleles and were able to discriminate between even closely related individuals more efficiently than RFLPs. Some mic rosatellite markers were more informative than others for assessing ge netic diversity. Single markers revealed 5.6-61.1% of the total variat ion detected by the 10 SSLP markers. Some marker combinations were com plementary, providing more information than others. Several combinatio ns of 4 SSLP markers detected as much as 94% of the total within-culti var variation detected by the 10 SSLP markers. These results suggest t hat the use of four well-chosen microsatellites would be an efficient method for evaluating the heterogeneity of rice accessions.