Abstract
We previously reported that, (1) increasing UVB radiation inhibited growth, yield, and grain development, (2) such UVB-induced damage caused by UVB-induced cyclobutane pyrimidine dimers (CPDs), and that (3) increasing CPD photolyase activity can significantly alleviate UVB-caused growth inhibition. In this study, to evaluate experimentally the influence of the solar-UVB on rice, we have conducted field experiment in Miyagi (2006-2008) and Kagoshima (2008) Pref., using UVB-resistant rice Koshihikari (japonica) with higher photolyase activity and the UVB-sensitive chromosomal segment substitution line (SL-229), substituted chr.10 by UVB-sensitive rice Kasalath (indica), as experimental plant: CPD photolyase gene locates on chr.10. As a result, grain size and pollen fertility of SL-229 grown under current outdoor conditions were reduced, and the degrees of SL-229 grown in Kagoshima Pref. were higher than in Miyagi Pref. These results mean that growth and yield of rice grown under current environmental conditions would be inhibited by UVB in natural sunlight.
