Assessment of genetic diversity in Oryza officinalis using morphological and SSR markers
2009
Mercado, S.M.Q. | Naredo, M.E.B. | McNally, K.L., International Rice Research Inst., Los Baños, Laguna (Philippines) T.T. Chang Genetic Resources Center
Oryza officinalis is the most common and widely distributed species among the species under the Ser. Latifoliae of the genus Oryza. Seventy-two O.officinalis accessions were selected to represent the distribution pattern of the species across Southeast Asia, Bangladesh, China, India, Nepal and Papua New Guinea. The samples were phenotyped using 25 quantitative and 17 qualitative morphological traits. Allelic diversity was screened using 23 SSR markers. Multivariate analyses based on nominal characters or quantitative traits showed that samples were differentiated according to their geographic distribution. Materials from China, India, and Myanmar (mainly South Asia) formed a cluster distinct from accessions coming from the Philippines, Indonesia, Vietnam, Malaysia and Brunei, and Papua New Guinea (mainly Southeast Asia), SSR analysis revealed 97 alleles ranging from 2 to 18 alleles per locus. Gene diversity (He) of the populations ranged from 0.0138 (RM447) to 0.9028 (RM224) with a mean of 0.5760. Based on the data for the 72 accessions, the diversity of the species is relatively high with materials from South East Asia having a higher diversity (He=0.5354) compared to South Asia (He=0.4853). Clusters generated using DARwin showed 5 major groups with some outliers. There is however, no distinct clustering of species based on their geographic distribution. Population structure was analyzed using the model-based methods of STRUCTURE and Instruct with K=4 and K=8, as the best fits, respectively. Both methods identified some putative admixture among the materials.
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