Abstract
Rice cultivars (Oryza sativa) vary widely in their sensitivities to UVB. Many UVB-resistant cultivars belong to Japanese lowland group and boro ecotype. Among Japanese lowland and indica cultivars, Sasanishiki was most resistant to UVB followed by Norin 1 and Surjamkhi (indica) in this order. Cyclobutane pyrimidine dimer (CPD) photorepair activity of Sasanishiki was greatest, while Surjamkhi was lowest. That of Norin 1 was intermediate. There were variations at positions 126 and 296 in amino acid sequences of CPD photolyases of these three cultivars. We suggested that the difference in the UVB sensitivity in rice might be caused by structural alteration of CPD photolyase due to variation in amino acid sequence. We report here correlation between UVB sensitivity, activity and amino acid sequence of CPD photolyase in wild rice (O. rufipogon from Asia, O. meridionalis from Australia, and O. barthii from Africa).
