Overexpression of a Chinese cabbage BrERF11 transcription factor enhances disease resistance to Ralstonia solanacearum in tobacco

Ethylene-responsive factors (ERFs) play diverse roles in plant growth, developmental processes and stress responses. However, the roles and underlying mechanism of ERFs remain poorly understood, especially in non-model plants. In this study, a full length cDNA of ERF gene was isolated from the cDNA library of Chinese cabbage. According to sequence alignment, we found a highly conservative AP2/ERF domain, two nuclear localization signals, and an ERF-associated Amphiphilic Repression (EAR) motif in its C-terminal region. It belonged to Villa group ERFs sharing the highest sequence identity with AtERF11 in all of the ERFs in Arabidopsis and designated BrERF11. BrERF11-green fluorescence protein (GFP) transient expressed in onion epidermis cells localized to the nucleus. The transcript levels of BrERF11 were induced by exogenous salicylic acid (SA), methyl jasmonate (MeJA), ethephon (ETH), and hydrogen peroxide (H2O2). Constitutive expression of BrERF11 enhanced tolerance to Ralstonia solanacearum infection in transgenic tobacco plants, which was coupled with hypersensitive response (HR), burst of H2O2 and upregulation of defense-related genes including HR marker genes, SA-, JA-dependent pathogen-related genes and ET biosynthesis associated genes and downregulation of CAT1, suggesting BrERF11 may participate in pathogen-associated molecular pattern (PAMP)- and effector-triggered immunity (PTI and ETI) mediated by SA-, JA- and ET-dependent signaling mechanisms. (c) 2012 Elsevier Masson SAS. All rights reserved.

乙烯响应因子（ERFs）在植物生长、发育过程以及胁迫响应中发挥着多种作用。然而，ERFs的作用及其潜在机制仍知之甚少，尤其是在非模式植物中。在本研究中，从大白菜的cDNA文库中分离出一个ERF基因的全长cDNA。通过序列比对，我们在其C末端区域发现了一个高度保守的AP2/ERF结构域、两个核定位信号以及一个与ERF相关的两亲性抑制（EAR）基序。它属于Ⅴ类ERFs，与拟南芥所有ERFs中的AtERF11具有最高的序列同一性，并被命名为BrERF11。在洋葱表皮细胞中瞬时表达的BrERF11 - 绿色荧光蛋白（GFP）定位于细胞核。BrERF11的转录水平受到外源水杨酸（SA）、茉莉酸甲酯（MeJA）、乙烯利（ETH）和过氧化氢（H₂O₂）的诱导。BrERF11的组成型表达增强了转基因烟草植株对青枯雷尔氏菌感染的耐受性，这与过敏反应（HR）、过氧化氢的爆发以及包括HR标记基因、依赖SA和JA的病程相关基因以及与乙烯生物合成相关基因在内的防御相关基因的上调和CAT1的下调相关联，表明BrERF11可能参与由依赖SA、JA和ET的信号机制介导的病原相关分子模式（PAMP）和效应物触发的免疫（PTI和ETI）。（c）2012爱思唯尔马松公司。版权所有。