Discrimination between Oryza malampuzhaensis Krish. et Chand. and Oryza officinalis Wall ex Watt based on RAPD markers and morphological traits

Abstract

Oryza malampuzhaensis, one of the tetraploid taxa of the genusOryza, is geographically restricted to Western Ghats of South India. Its taxonomic status is not well established and is generally treated as a tetraploid race of O. officinalis. Sixty-three morphological traits and 262 random amplified polymorphic DNA (RAPD) markers generated by 23 random decamer primers were used to assess the genetic relationship between O. malampuzhaensis and O. officinalis. Pair wise comparisons based on both RAPDs and morphological traits revealed 60% genetic distance between the two taxa and was significantly higher (p <0.01) than the corresponding intra-specific distances. Cluster and principal component analysis (PCA) of genetic distance estimations based on RAPDs and morphological traits clearly differentiated the two taxa. High frequency of discrete O. malampuzhaensis specific RAPDs (21%) and the significantly higher (p < 0.05) mean number of amplification products per individual in O. malampuzhaensis observed in the study reflect its allopolyploid nature. Low genetic diversity within O. malampuzhaensis revealed by RAPD analysis indicates the recent origin of this taxa. The RAPD analysis further revealed the possibility that the putative ‘C’ genomeprogenitor of O. malampuzhaensis is a close relative of O. officinalis. In addition, amplification products diagnostic to O. malampuzhaensis were identified. The results of the present study clearly demonstrated that the O. malampuzhaensis is a distinct entity, and support the recent conclusion that O. malampuzhaensis has diverged enough to deserve species status.