Fu X, Sudhakar D, Peng J, Richards D E, Christou P, Harberd N P
John Innes Centre, Norwich Research Park, Colney Lane, Norwich NR4 7UH, United Kingdom.
Plant Cell. 2001 Aug;13(8):1791-802. doi: 10.1105/tpc.010020.
Bioactive gibberellins (GAs) are essential endogenous regulators of plant growth. GA signaling is mediated via GAI, a nuclear member of the GRAS family of plant transcription factors. Previous experiments have suggested that GAI is a GA-derepressible repressor of plant growth. Here we test this hypothesis by examining the effects of the expression of Arabidopsis GAI in transgenic Basmati rice. High-level expression of GAI caused dwarfism and reduced GA responses, and the strength of this effect was correlated with the level of transgene expression. In particular, the expression of GAI abolished the GA-mediated induction of rice aleurone alpha-amylase activity, thus implicating GAI orthologs in the well-characterized cereal aleurone GA response. The GA derepressible repressor model predicts that high-level expression of GAI should confer dwarfism, and these observations are consistent with this prediction.
生物活性赤霉素（GAs）是植物生长必需的内源性调节因子。GA信号通过GAI介导，GAI是植物转录因子GRAS家族的一个核成员。先前的实验表明，GAI是植物生长的GA去抑制型阻遏物。在这里，我们通过检测拟南芥GAI在转基因巴斯马蒂水稻中的表达效应来验证这一假设。GAI的高水平表达导致矮化并降低了GA反应，且这种效应的强度与转基因表达水平相关。特别是，GAI的表达消除了GA介导的水稻糊粉层α-淀粉酶活性的诱导，从而表明GAI直系同源物参与了特征明确的谷物糊粉层GA反应。GA去抑制型阻遏物模型预测，GAI的高水平表达应该导致矮化，而这些观察结果与这一预测一致。
