水稻病程相关基因OsPR1b启动子的表达特性研究

Expression Characteristics of Rice OsPR1b Gene Promoter

目的:分析水稻病程相关基因OsPR1b的表达特性,以进一步了解其表达和调控机制。方法:利用PCR技术从水稻日本晴基因组中扩增OsPR1b基因的启动子片段,命名为OsPR1bp,并构建相应的OsPR1bp::GUS融合表达载体,采用农杆菌介导的转基因技术获得转基因植株,进行GUS组织化学分析;利用Real-time PCR对OsPR1b基因在植物激素、非生物因子和水稻白叶枯菌(Xoo)毒性菌株P10(PXO124)处理下的表达水平进行分析。结果:GUS组织染色结果表明OsPR1b在水稻叶片中的表达量较高,而在茎、根、愈伤和花器中的表达量较低;植物激素水杨酸(SA)、茉莉酸甲酯(MeJA)、激动素(KT)、脱落酸(ABA)及NaCl、PEG均可不同程度地提高OsPR1b在叶片中的表达水平,Me-JA、KT和NaCl的处理能提高其在根部的表达水平,但这些激素在诱导OsPR1b在叶片和根部的表达程度上存在明显差异;单独接种Xoo毒性菌株P10 24 h对OsPR1b表达的影响不大,而MeJA与其共同处理后则可显著增强其在叶片中的表达。结论:作为一种防卫基因,OsPR1b在健康植株中的表达水平较低,容易受盐/干旱胁迫及Xoo病原菌的诱导,多种植物激素如JA、KT和ABA很可能作为信号分子参与激活和介导了这种系统性的反应。

Objective： In order to gain further insight into the expression/regulation of marker gene OsPR1b in rice immune response, expression analysis of OsPR1b in rice was carried out. Methods： OsPR1b gene promoter fragment was amplified using the technology of PCR from rice Nipponbare genome and named OsPR1bp. The plas-mid of OsPR1bp：：GUS was introduced into japonica rice via Agrobacterium-mediated transformation for further histo-chemical GUS analysis. In addition, the expression level of OsPR1b gene in rice leaves and roots was analyzed af-ter treated with plant hormones, abiotic factors and Xanthomonas oryzae pv. oryzae（Xoo） P10（PXO124） strain re-spectively. Results： The expression level of OsPR1b gene was much higher in leaf than that in stem, root, callus and flower. The expression of OsPR1b in leaves was differentially increased under the treatments of salicylic acid （SA）, methyl jasmonate（MeJA）, kinetin（KT）, abscisic acid（ABA） as well as NaCl and PEG. The expression of OsPR1b in roots was increased under the treatments of MeJA, KT and NaCl. However, the increased fold of ex-pression were different between leaves and roots. Inoculation with P10 alone for 24 h had no effect on OsPR1b ex-pression, while co-treated with MeJA can significantly enhanced the expression level of OsPR1b in leaves. Conclu-sion： OsPR1b is described as a defense gene and the promoter we isolated directed a very low GUS gene expres-sion under normal conditions but responded to salt/drought stress and Xoo, and plants hormones such as JA, KT and ABA probably act as signals to trigger and mediate the systematic response.