Abstract

Plant hormones play major roles in abiotic stress. This study shows that gibberellin acid-inefficient transgenic rice (Oryza sativa L.) is more tolerant to drought and salinity stress. We also investigated the underlying molecular mechanism by which plants respond to salinity and drought stress. We previously showed how the HD-Zip family I gene Oshox4 (Homeobox 4) regulates GA deactivation by controlling DELLA subfamily and rice GA 2-oxidase and GA 3-oxidase genes in rice. Here we investigated the role of rice Oshox4 gene for drought and salinity stress tolerance. Phenotypic analysis indicated that Oshox4 transgenic lines are more tolerant to drought and salinity stress relative to non-transgenic IR64 plants. To explain the strong osmotic stress tolerance of Oshox4 transgenic lines, we studied the expression of rice GA 2-oxidase, rice YABBY, rice KRP, and rice GRAS gene families. qRT-PCR results showed that OsGA2ox4, OsGA2ox6, OsGA2ox8, OsGAI and OsSCRL were highly expressed under severe drought in Oshox4 transgenic plants. Oshox4 enhanced the expression of OsGA2ox5, OsKRP2 and OsKRP5 under 50 mM salt treatment and OsSCRL under 200 mM salt treatment. Our findings have confirmed that Oshox4 transgenic rice plants are more tolerant to drought and salinity stress and that Oshox4 plays a role in rice osmatic tolerance. This study provides novel insights into methods of maintaining higher yield amidst a limited supply of water by improving physiological conditions.

中文翻译：

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Oshox4的过表达增强了水稻的耐旱和耐盐性

摘要

植物激素在非生物胁迫中起主要作用。这项研究表明，赤霉素低酸转基因水稻（Oryza sativa L.）对干旱和盐分胁迫的耐受性更高。我们还研究了植物响应盐分和干旱胁迫的潜在分子机制。我们之前曾展示过HD-Zip家族I基因Oshox4（Homeobox 4）如何通过控制DELLA亚家族和水稻中的GA 2-氧化酶和GA 3-氧化酶基因来调节GA失活。在这里，我们调查了水稻Oshox4基因在干旱和盐碱胁迫耐受性中的作用。表型分析表明，Oshox4相对于非转基因IR64植物，转基因品系更耐干旱和盐分胁迫。为了解释Oshox4转基因株系的强渗透胁迫耐受性，我们研究了水稻GA 2-氧化酶，水稻YABBY，水稻KRP和水稻GRAS基因家族的表达。qRT-PCR结果表明，Oshox4转基因植物在严重干旱下高表达OsGA2ox4，OsGA2ox6，OsGA2ox8，OsGAI和OsSCRL。在50 mM盐处理和OsSCRL处理下，Oshox4增强了OsGA2ox5，OsKRP2和OsKRP5的表达。在200 mM盐处理下。我们的发现已经证实，Oshox4转基因水稻植物对干旱和盐分胁迫具有更强的耐受性，并且Oshox4在水稻的渗透压耐受中发挥了作用。这项研究为通过改善生理条件在有限的水供应中维持较高产量的方法提供了新见解。