Abstract
Lower or higher temperature stress reduces seed setting rate in several plant species. In this phenomenon, development of pollen is more sensitive to the stress than that of female gamate. In this study, we aimed to elucidate the role of gibberellin in low-temperature injury of rice. Rice plants were cultured in a growth cabinet under 27C day/ 22C night with a 12-h photoperiod prior initiating panicle development, and were transferred to deep cool water (20.5C) as low-temperature treatment until heading period. As a result, under low temperature conditions, the number of mature pollen and the seed setting rate were significantly reduced. In addition, certain gibberellins-insensitive mutants became much more sensitive to low-temperature stress. Moreover, in Koshihikari sd1 (Tsukuba 1) lacking SD1 gene, which encodes a gibberellin biosynthesis enzyme, the injury was much severe than that of parental line Koshihikari. On the other hand, we could not find any influence on the female development under these experimental conditions. These findings suggest that gibberellin and its signaling make an important and essential contribution to cold tolerance in anther development.
