A study of genetic diversity in Oryza rhizomatis D.A. Vaughan accessions using AFLP markers and morphological traits
G. Rajkumar*, O.V.D.S.J. Weerasena and K.K.S. Fernando
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Abstract: Oryza rhizomatis is a wild rice species endemic to Sri Lanka and is reported to have tolerance to biotic and abiotic stresses prevailing in the dry zone of the country. Several morphological differences have been observed in O. rhizomatis grown under different agro-ecological conditions of Sri Lanka. Therefore, these rice species (accessions) may have genetic differences to consider them as ‘ecotypes’. Morphological and genetic diversity of O.rhizomatis accessions collected from different locations were carried out to observe genetic differences among them. Scattered diagram of PCoA of O. rhizomatis accessions, based on morphological data showed that there were no significant differences among them. According to molecular analysis by AFLP, all the accessions were genetically similar and Jaccard genetic similarity coefficient varied with a very narrow range between the accessions (0.915 to 1.000). According to the results, the O. rhizomatis accessions tested did not show significant morphological and genetic differences. In this study representative samples from different locations were grown in the green house, exposing them to the same environmental conditions. This may have contributed to results obtained with no observable morphological differences. Further studies have to be carried out with insitu collections from different locations when extreme weather conditions are prevailing to see the morphological characters are changed as an adaptation and to assess any genetic diversity.
Fig.: Two dimensional PCoA plot of relationships among Oryza rhizomatis accessions based on thirty nine morphological parameters. Ovale indicate the well- defined group.