Wang Xiao'e, Basnayake B M Vindhya S, Zhang Huijuan, Li Guojun, Li Wei, Virk Nasar, Mengiste Tesfaye, Song Fengming
State Key Laboratory for Rice Biology, Institute of Biotechnology, Zhejiang University-Huajiachi Campus, Hangzhou, Zhejiang 310029, People's Republic of China.
Mol Plant Microbe Interact. 2009 Oct;22(10):1227-38. doi: 10.1094/MPMI-22-10-1227.
Transcription factors of the NAC family are known to be involved in various growth or developmental processes and in regulation of response to environmental stresses. In the present study, we report that Arabidopsis ATAF1 is a negative regulator of defense responses against both necrotrophic fungal and bacterial pathogens. Expression of ATAF1 was downregulated after infection with Botrytis cinerea or Pseudomonas syringae pv. tomato or after treatment with salicylic acid (SA), jasmonic acid, and 1-amino cyclopropane-1-carboxylic acid (the precursor of ethylene biosynthesis). Transgenic plants that overexpress the ATAF1 gene (ATAF1-OE) showed increased susceptibility while expression of an ATAF1 chimeric repressor construct (ATAF1-SRDX) exhibited enhanced resistance to P. syringae pv. tomato DC3000, B. cinerea, and Alternaria brassicicola. The ataf1 mutant plants showed no significant resistance against the pathogens tested. After inoculation with B. cinerea or P. syringae pv. tomato DC3000, expressions of defense-related genes PR-1, PR-5. and PDF1.2 were upregulated in the ATAF1-SRDX plants but attenuated or unchanged in the ATAF1-OE plants. In ATAF1-OE plants, SA-induced expression of pathogenesis-related genes and disease resistance against P. syringae pv. tomato DC3000 was partially suppressed. Increased levels of reactive oxygen species (i.e., H(2)O(2) and superoxide anion) accumulated only in the ATAF1-OE but not in the ATAF1-SRDX plants after Botrytis spp. infection. Our studies provide direct genetic evidence for the role of ATAF1 as a negative regulator of defense response against different type of pathogens.
已知NAC家族的转录因子参与各种生长或发育过程以及对环境胁迫的响应调节。在本研究中，我们报道拟南芥ATAF1是对坏死营养型真菌和细菌病原体防御反应的负调节因子。在感染灰葡萄孢菌或丁香假单胞菌番茄致病变种后，或在水杨酸（SA）、茉莉酸和1-氨基环丙烷-1-羧酸（乙烯生物合成前体）处理后，ATAF1的表达下调。过表达ATAF1基因的转基因植物（ATAF1-OE）表现出易感性增加，而ATAF1嵌合阻遏物构建体（ATAF1-SRDX）的表达对丁香假单胞菌番茄致病变种DC3000、灰葡萄孢菌和链格孢表现出增强的抗性。ataf1突变体植物对所测试的病原体没有明显抗性。接种灰葡萄孢菌或丁香假单胞菌番茄致病变种DC3000后，防御相关基因PR-1、PR-5和PDF1.2在ATAF1-SRDX植物中上调，但在ATAF1-OE植物中减弱或不变。在ATAF1-OE植物中，SA诱导的病程相关基因表达和对丁香假单胞菌番茄致病变种DC3000的抗病性部分受到抑制。在葡萄孢菌感染后，仅在ATAF1-OE植物中积累了增加水平的活性氧（即H₂O₂和超氧阴离子），而在ATAF1-SRDX植物中未积累。我们的研究为ATAF1作为针对不同类型病原体防御反应的负调节因子的作用提供了直接的遗传证据。
