Host: The Japan Radiation Research Society
Rice cultivars vary widely in their UVB sensitivity and this has been correlated with CPD photolyase mutations that alter the structure/function of this photorepair enzyme. Here, in order to test whether CPD photolyase function determines the UVB sensitivity of rice, we constructed transgenic plants bearing the CPD photolyase gene of the UV-resistant rice cultivar Sasanishiki (japonica) in the sense or the antisense orientation using the Sasanishiki (sense; S-B and S-C lines, antisense; AS-D line), UVB-sensitive Norin 1 (japonica) (SN-F line) and UVB-sensitive Surjamkhi (indica) (SSu-B line) rice as wild-type plants. The sense transgenic plants had higher photolyase activities than the each wild-type plant, were significantly more resistant to UVB-caused growth inhibition, and maintained significantly lower CPD levels in their leaves during growth under elevated UVB radiation. Conversely, the antisense transgenic plant had little photolyase activity, was severely damaged by elevated UVB radiation, and maintained higher CPD levels in its leaves during growth under UVB radiation. These results strongly indicate that CPDs are one of principal cause of UVB-induced growth inhibition in rice, and that increasing CPD photolyase activity can significantly produce alleviation of UVB-caused growth inhibition.
