Abstract:

The rice Rim2 is a unique stress-induced transposon superfamily recently identified in Oryza genomes. The polymorphisms of Rim2 core region provide a novel technique to fingerprint rice genetic variation. In the past decade, DNA markers such as RAPD, AFLP, RFLP and SSR have been extensively used for fingerprinting and exploring the genetic diversity and evolutionary relation of rice genetic resources. In this paper, Rim2 elements were used as the DNA marker to fingerprint indica and japonica hybrid rice and to predict their heterosis according to the molecularly genetic distance. Five pairs of PCR primers based on the Rim2 sequences were selected to amplify cDNA of twenty-one indica and twenty japonica rice, including three sterile lines, nine restoring lines and nine hybrids in indica and three sterile lines, eight restoring lines and nine hybrids in japonica. A total of thirty-eight bands were obtained, of which twenty-six were polymorphic, accounting for 69.64%. The average polymorphism rate of japonica was 56.67%, which was apparently higher than that of indica. The dendrogram based on Nei’s distance showed that twenty-one indica rice and twenty japonica rice could be divided into six groups and seven groups respectively. The analysis of genetic relationship among materials showed that Rim2 molecular fingerprint could distinguish most of indica or japonica rice. Correlations were found in japonica rice between the genetic distance of parents and their hybrid heterosis, while not in indica rice. These findings demonstrate the potential of developing a more powerful molecular tool based on the tremendous variability of the Rim2 superfamily to explore on administration of seed production, variety licensing, marker-aid selection in breeding programs, such as RAPD, AFLP, RFLP and SSR have achieved.

Key words: Oryza sativa L., Rim2 molecular fingerprint, Dendrogram, Heterosis