我国人口众多，保障粮食生产安全显得更加重要。粮食生产高度依赖于水资源，而水资源濒乏严重制约粮食生产安全。在世界经济的发展特别是发展中国家的发展对水资源的需求日趋增加，缺水的情况逐渐加剧的情况下，一方面不断提高水资源管理水平提高粮食生产，另一方面利用生物技术手段特别是转基因技术育种有效地提高农作物抗干旱和抗盐碱能力，为我国粮食生产提供有力的保障，已经成为了一个重要的关键技术。在农作物转基因技术日趋成熟背景下，挖掘行之有效地抗干旱基因是农业生物技术发展迫切需求。中科院版纳植物园功能基因研究组余迪求研究员领导的研究小组从水稻逆境诱导的cDNA文库中克隆获得一个能有效调控植物抗干旱和盐碱能力的转录调节基因WRKY45。表达谱分析表明，OsWRKY45受干旱、盐碱、病源菌等多种逆境因子，以及非生物逆境调控激素脱落酸（ABA）处理而强烈诱导表达。在转基因拟南芥中过量表达OsWRKY45可以激活植物抗病相关基因PRs的表达，从而提高植物对病原菌的抗性。另一方面，该基因也能有效地提高转基因植物对高盐及干旱的耐性，同时减弱了转基因植物在萌发阶段及其后期的幼苗生长阶段对ABA的敏感性，一些逆境相关基因及ABA合成基因的表达也有所增强。进一步研究证实，OsWRKY45也能有效地提高转基因水稻抗干旱能力。这揭示了OsWRKY45可以提高多种植物抗干旱能力，具有广泛的应用前途。
一般而言，如果一个基因能够有效地提高转基因植株对逆境的抗性水平，那么该基因必定会降低转基因植物的生物量，从而导致产量降低。然而OsWRKY45基因就表现出不同的特征，在水稻和拟南芥中高表达该基因后不仅能有效地提高转基因植株抗干旱能力，而且不会引起任何转基因植物在其形态发生、花器官发育、授粉特征、结实率及最终产量等指标没有任何降低，相反还有一定程度的改善。
相关研究结果发表在爱思唯尔期刊《环境与实验植物学》（Environmental and Experimental Botany）上。（生物谷Bioon.com）
生物谷推荐原始出处：
Environmental and Experimental Botany，doi:10.1016/j.envexpbot.2008.07.002，Yuping Qiu，Diqiu Yu
Over-expression of the stress-induced OsWRKY45 enhances disease resistance and drought tolerance in Arabidopsis
Yuping Qiua, b and Diqiu Yua, ,
aXishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Kunming 650223, PR China
bGraduate School of the Chinese Academy of Sciences, Beijing 100039, PR China
Abstract
The WRKY transcriptional factor superfamily regulates diverse functions, including processes such as plant development and stress response. In this study, we have shown that the rice WRKY45 (OsWRKY45) expression is markedly induced in response to stress-related hormone abscisic acid (ABA) and various stress factors, e.g., application of NaCl, PEG, mannitol or dehydration, treatment with 0 °C and 42 °C as well as infection by Pyricularia oryzae Cav. and Xanthomonas oryzae pv. oryzae. Together, these results indicate that the OsWRKY45 may be involved in the signal pathways of both biotic and abiotic stress response. Further analyses of 35S:OsWRK45 Arabidopsis plants have shown that ectopic, constitutive over-expression of the OsWRKY45 transgene confers a number of properties to transgenic plants. These properties include significantly increased expression of PR genes, enhanced resistance to the bacterial pathogen Pseudomonas syringae tomato DC3000, enhanced tolerance to salt and drought stresses, decreased sensitivity toward ABA signalling during seed germination and post-germination processes, and modulation of ABA/stress-regulated genes during drought induction. In addition, higher levels of OsWRKY45 expression in transgenic plants correlate positively with the strength of the abiotic and biotic responses mentioned above. More specifically, the decreased ABA sensitivities, the enhanced disease resistance and drought tolerances may be attributed, in part, to stomatal closure and induction of stress-related genes during drought induction. The relationship between OsWRKY45 expression and ABA signalling is discussed.
