Abstract
Japanese rice (Oryza sativa L.) cultivars vary widely in their sensitivity to UVB radiation. We previously showed that cyclobutane pyrimidine dimer (CPD)-photorepair activity in UVB-sensitive Norin 1 was lower than in its close relative UVB-resistant Sasanishiki, and that the CPD-photorepair deficiency in Norin 1 resulted from a functionally altered photolyase. There was a variation between the deduced amino acid sequences of Norin 1 and Sasanishiki CPD photolyases. These results suggested that the difference in the UVB-sensitivity between those two cultivars might be due to the structural alteration of CPD photolyase. In this study, we investigated the deduced amino acid sequences of photolyases, CPD-photolyase activities in vitro and the UVB-sensitivities of close relatives and progenitors of Sasanishiki and Norin1. Two genotypes of CPD photolyase were found. One is the "Sasanishiki type" and the other was "Norin 1 type". We discuss the relationship among the difference in the UVB-sensitivities, CPD photolyase activities and genotypes of CPD photolyase. [J Radiat Res 44:416 (2003)]
