Duan Yanjiao, Jiang Yuanzhong, Ye Shenglong, Karim Abdul, Ling Zhengyi, He Yunqiu, Yang Siqi, Luo Keming
Key Laboratory of Eco-environments of Three Gorges Reservoir Region, Ministry of Education, Chongqing Key Laboratory of Transgenic Plant and Safety Control, School of Life Sciences, Institute of Resources Botany, Southwest University, No. 1, Tiansheng Road, Beibei, 400715, Chongqing, China.
Plant Cell Rep. 2015 May;34(5):831-41. doi: 10.1007/s00299-015-1745-5. Epub 2015 Jan 28.
A salicylic acid-inducible WRKY gene, PtrWRKY73, from Populus trichocarpa , was isolated and characterized. Overexpression of PtrWRKY73 in Arabidopsis thaliana increased resistance to biotrophic pathogens but reduced resistance against necrotrophic pathogens. WRKY transcription factors are commonly involved in plant defense responses. However, limited information is available about the roles of the WRKY genes in poplar defense. In this study, we isolated a salicylic acid (SA)-inducible WRKY gene, PtrWRKY73, from Populus trichocarpa, belonging to group I family and containing two WRKY domains, a D domain and an SP cluster. PtrWRKY73 was expressed predominantly in roots, old leaves, sprouts and stems, especially in phloem and its expression was induced in response to treatment with exogenous SA. PtrWRKY73 was localized to the nucleus of plant cells and exhibited transcriptional activation. Overexpression of PtrWRKY73 in Arabidopsis thaliana resulted in increased resistance to a virulent strain of the bacterial pathogen Pseudomonas syringae (PstDC3000), but more sensitivity to the necrotrophic fungal pathogen Botrytis cinerea. The SA-mediated defense-associated genes, such as PR1, PR2 and PAD4, were markedly up-regulated in transgenic plants overexpressing PtrWRKY73. Arabidopsis non-expressor of PR1 (NPR1) was not affected, whereas a defense-related gene PAL4 had reduced in PtrWRKY73 overexpressor plants. Together, these results indicated that PtrWRKY73 plays a positive role in plant resistance to biotrophic pathogens but a negative effect on resistance against necrotrophic pathogens.
从毛果杨中分离并鉴定了一个水杨酸诱导型WRKY基因PtrWRKY73。PtrWRKY73在拟南芥中的过表达增强了对活体营养型病原菌的抗性，但降低了对死体营养型病原菌的抗性。WRKY转录因子通常参与植物的防御反应。然而，关于WRKY基因在杨树防御中的作用，目前可用信息有限。在本研究中，我们从毛果杨中分离出一个水杨酸（SA）诱导型WRKY基因PtrWRKY73，它属于第一组家族，包含两个WRKY结构域、一个D结构域和一个SP簇。PtrWRKY73主要在根、老叶、芽和茎中表达，尤其是在韧皮部，其表达受外源SA处理诱导。PtrWRKY73定位于植物细胞核并表现出转录激活活性。PtrWRKY73在拟南芥中的过表达导致对细菌病原菌丁香假单胞菌（PstDC3000）的强毒株的抗性增强，但对死体营养型真菌病原菌灰葡萄孢更敏感。SA介导的防御相关基因，如PR1、PR2和PAD4，在过表达PtrWRKY73的转基因植物中显著上调。拟南芥PR1非表达子（NPR1）不受影响，而防御相关基因PAL4在PtrWRKY73过表达植物中表达降低。这些结果共同表明，PtrWRKY73在植物对活体营养型病原菌的抗性中起积极作用，但对死体营养型病原菌的抗性起消极作用。
