水稻抗病相关基因的分离克隆和功能鉴定  

Isolation and functional characterization of pathogen-induced defense-responsive genes of rice

作　　者：丁新华[1] 

机构地区：[1]华中农业大学生命科学技术学院,武汉430070

出　　处：《华中农业大学学报》2011年第1期121-123,共3页Journal of Huazhong Agricultural University

摘　　要：水稻白叶枯病和稻瘟病分别是由白叶枯病菌（Xanthomonas oryzae pv.oryzae,Xoo）和稻瘟病菌（Magnaporthe grisea）引起，是世界水稻生产中的两大重要病害，造成的损失巨大。通过改良水稻自身防御体系来控制病害，是一种既经济又绿色的方法。鉴定水稻抗病相关基因，研究水稻抗病机理对改良水稻有着重要的理论意义和应用前景。植物激素生长素诱导的信号通常被认为能调节植物的生长和发育。本研究报道的水稻基因GH3-8是1个生长素反应基因，在依赖于生长素的发育中发挥功能，同时也调节不依赖于水杨酸和茉莉酸的信号路径的抗病反应。白叶枯病菌诱导水稻至少在被侵染部位合成生长素，而生长素继而诱导水稻大量合成松弛细胞壁的蛋白质——伸展蛋白（α-和β-expansins），破坏细胞壁对病原菌的先天屏障作用，以利病原菌在水稻中生长繁殖。在携带有抗病基因Xa21或Xa26抗病水稻品种中，病原菌引起的水稻感染部位生长素的合成可诱导水稻快速合成IAA酰胺合成酶GH3-8。GH3-8通过催化IAA-氨基酸的合成抑制生长素的作用，从而阻止细胞壁的松弛，增强植物对病原菌的自身免疫功能。超量表达GH3-8基因增强水稻对白叶枯菌的抗性，同时也延缓了植株的生长和发育，至少部分抑制了生长素信号,从而抑制了α-和β-expansins的合成。本研究结果揭示了病原菌利用生长素作为毒性因子侵染水稻的机理以及水稻应对这一毒性因子的调控途径，同时也从一个方面解释了植物在抗病反应中通常要付出生长被抑制的代价的原因。超量表达GH3-8导致植株不育。通过正反交试验显示GH3-8超量表达植株是雄性和雌性都不育。通过形态学观察发现，GH3-8超量表达植株的雌蕊柱头发育不正常；通过激光共聚焦显微镜对雌蕊胚囊观察发现，GH3-超量表达植株的成熟胚囊发育不�Rice bacterial blight disease caused by Xanthomonas oryza pv.oryza and fungal blast disease caused by Magnaporthe grisea,are two of the most devastating diseases of rice worldwide.These two diseases can lead to tremendous yield loss every year.Efficient control of disease through improving rice defense system is economic and environment friendly.Characterizing rice disease resistance related genes and elucidating the mechanism of rice disease resistance are important both in scientific theory and in rice improvement.The signaling induced by the plant growth hormoneauxin is generally recognized to regulate plant growth and development.Here we report rice GH3-8,an auxin-responsive gene functioned in auxin-dependent development,activates disease resistance in a salicylic acid–and jasmonic acid–signaling-independent pathway.Bacteria induce accumulation of indole-3-acetic acid （IAA）,the major type of auxin in rice.IAA induces the expression of α- and β-expansins,the proteins that are known to loose cell wall,the native barrier of biotic intruder,to facilitate the growth of cells.In rice resistance variety carrying Xa21 or Xa26,the infection of bacteria induce rice to synthesize GH3-8 in infection site of rice. GH3-8 encodes an IAA-amino synthetase that prevents free IAA accumulation and looseness of cell wall.Over-expression of GH3-8 enhanced disease resistance and delayed growth and development,which is partly due to inhibiting the expression of α- and β-expansins via suppressing auxin signaling.Here we show the mechanism of bacteria hijacks auxin as virulence factor to infect rice,and the regulating pathway of rice to the virulence factor; in addition to,explain the cause that plants growth was restrained in disease resistance. Overexpression of GH3-8 results in sterility of plants.Analysis of forward and reverse cross showed that GH3-8-overexpressing plants were male sterility and female sterility.We found that the stigmas of GH3-8-overexpressing plants are abnormal by morphological observation.We obser

关 键 词：水稻 白叶枯病 稻瘟病 抗病相关基因 生长素 水杨酸 茉莉酸 基础抗性 伸展蛋白 GH3—8 维生系B1 类病斑突变体 凋亡 

分 类 号：S512.1[农业科学—作物学]