Instituto de Biología Molecular y Celular de Plantas (IBMCP), Universidad Politécnica de Valencia (UPV)-Consejo Superior de Investigaciones Científicas (CSIC), Ingeniero Fausto Elio s/n, 46022 Valencia, Spain.
J Plant Physiol. 2011 Feb 15;168(3):233-41. doi: 10.1016/j.jplph.2010.07.023.
We examined the gibberellin (GA) and ethylene regulation of submergence-induced elongation in seedlings of the submergence-tolerant lowland rice (Oryza sativa L.) cvs Senia and Bomba. Elongation was enhanced after germination to facilitate water escape and reach air. We found that submergence-induced elongation depends on GA because it was counteracted by paclobutrazol (an inhibitor of GA biosynthesis), an effect that was negated by GA(3). Moreover, in the cv Senia, submergence increased the content of active GA(1) and its immediate precursors (GA(53), GA(19) and GA(20)) by enhancing expression of several GA biosynthesis genes (OsGA20ox1 and -2, and OsGA3ox2), but not by decreasing expression of several OsGA2ox (GA inactivating genes). Senia seedlings, in contrast to Bomba seedlings, did not elongate in response to ethylene or 1-aminocyclopropane-1-carboxylic-acid (ACC; an ethylene precursor) application, and submergence-induced elongation was not reduced in the presence of 1-methylcyclopropene (1-MCP; an ethylene perception inhibitor). Ethylene emanation was similar in Senia seedlings grown in air and in submerged-grown seedlings following de-submergence, while it increased in Bomba. The expression of ethylene biosynthesis genes (OsACS1, -2 and -3, and OsACO1) was not affected in Senia, but expression of OsACS5 was rapidly enhanced in Bomba upon submergence. Our results support the conclusion that submergence elongation enhancement of lowland rice is due to alteration of GA metabolism leading to an increase in active GA (GA(1)) content. Interestingly, in the cv Senia, in contrast to cv Bomba, this was triggered through an ethylene-independent mechanism.
我们研究了赤霉素(GA)和乙烯对低地水稻(Oryza sativa L.)品种 Senia 和 Bomba 幼苗淹水诱导伸长的调节作用。在萌发后,幼苗伸长以促进水分逸出并到达空气。我们发现,淹水诱导的伸长取决于 GA,因为它被多效唑(一种 GA 生物合成抑制剂)抵消,而 GA(3)则可以消除这种作用。此外,在 Senia 品种中,淹水通过增强几个 GA 生物合成基因(OsGA20ox1 和 -2,以及 OsGA3ox2)的表达来增加活性 GA(1)及其直接前体(GA(53)、GA(19)和 GA(20))的含量,但不会通过降低几个 OsGA2ox(GA 失活基因)的表达来增加。与 Bomba 幼苗不同,Senia 幼苗对乙烯或 1-氨基环丙烷-1-羧酸(ACC;乙烯前体)的应用不伸长,并且在存在 1-甲基环丙烯(1-MCP;乙烯感知抑制剂)的情况下,淹水诱导的伸长不会减少。在 Senia 幼苗在空气中生长和淹水后再淹水时,乙烯的排放相似,而在 Bomba 中则增加。乙烯生物合成基因(OsACS1、-2 和 -3,以及 OsACO1)在 Senia 中的表达没有受到影响,但 OsACS5 的表达在 Bomba 中迅速在淹水时增强。我们的结果支持这样的结论,即低地水稻淹水伸长增强是由于 GA 代谢的改变导致活性 GA(GA(1))含量增加。有趣的是,在 Senia 品种中,与 Bomba 品种不同,这是通过一种乙烯非依赖的机制触发的。