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自然界中,植物利用自身的2道免疫防线来抵御病原微生物的侵染。第1道免疫防线是病原菌相关分子模式或微生物相关因子(pathogen or microbe associated molecular patterns, PAMPs/MAMPs)激发的免疫反应 (PAMPs triggered immunity, PTI)[1-2]。第2道免疫防线是植物抗病基因(resistance gene,R gene)识别病原微生物的效应蛋白后激发免疫反应(effectors triggered immunity, ETI),该免疫反应在侵染部位产生大量的细胞死亡,又称为超敏反应(Hypersensitive Response, HR)[3]。EDS1(enhanced disease susceptibility 1)在植物的2道免疫防线中均发挥着非常重要的作用[4-5],尤其在第2道免疫防线中,植物大多数TIR-NB-LRR(Toll-Interleukin1 Receptor-nucleotide binding-leucine-rich repeat)类抗病基因功能的正常发挥都需要EDS1的参与[6]。EDS1不仅可以与病原菌效应蛋白发生相互作用,还可以与植物体内TIR-NB-LRR类蛋白形成复合体,从而实现抗病信号通路的正常传递[7]。同时,植物体内存在与EDS1结构同源的另外2个蛋白PAD4(Phytoalexin Deficient 4)和SAG101(Senescence Associated Gene 101),EDS1,PAD4,SAG101三者都含有1个酰基酯酶结构域和1个EP(EDS1-PAD4)结构域[5,8]。EDS1可以分别与另外2个蛋白发生相互作用,介导不同的抗病信号通路[9]。近期的研究[10]发现,EDS1,PAD4,SAG101三者还可以形成复合体来发挥功能。综上所述,虽然研究者对EDS1在植物抗病中的功能有一定了解,但具体的EDS1信号通路上、下游作用元件是什么,目前还不清楚。橡胶树白粉菌 (Oidium heveae)是一种专性活体寄生真菌,侵染橡胶树引发橡胶树白粉病,对天然橡胶的产量造成了巨大的损失。近期的研究发现,橡胶树白粉菌还可以侵染拟南芥,在拟南芥野生型Col-0激发抗病反应,并且该抗病反应完全依赖于EDS1和PAD4,部分依赖于SAG101以及SA信号通路[11]。为了进一步研究橡胶树白粉菌在拟南芥上激发的抗病信号通路,本实验室对接种橡胶树白粉菌Oidium heveae HN1106的拟南芥野生型Col-0进行了RNA-seq数据分析,笔者旨在为进一步探讨EDS1参与的植物抗病信号通路奠定良好的基础。
ATAF2 positively contributes to the disease resistance against Oidium heveae in Arabidopsis
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摘要: 橡胶树白粉菌(Oidium heveae)侵染拟南芥野生型Col-0,激发拟南芥的抗病反应。该抗病反应依赖于EDS1(enhanced disease susceptibility 1),EDS1在TIR-NB-LRR(Toll-Interleukin1 Receptor-nucleotide binding-leucine-rich repeat)类抗性基因介导的抗病信号通路中发挥非常重要的作用,但目前还不清楚具体的EDS1上、下游作用元件是什么。为了进一步研究橡胶树白粉菌在拟南芥上激发的抗疾信号通路,本实验室对接种橡胶白粉菌oidium heveae HN1106的拟南芥野生型Col-0进行了RNA-Seq数据分析,结果表明,拟南芥Col-0在接种橡胶树白粉菌4 d后,NAC家族 (ATAF1,2 and CUC2, NAM)转录因子ATAF2基因上调表达20倍,并且正调控拟南芥对橡胶树白粉菌的抗病性。另外,笔者通过体外蛋白质pull-down试验和体内原生质体免疫共沉淀试验,发现ATAF2可以直接与EDS1发生相互作用,这为将来进一步阐明EDS1抗病信号通路奠定了很好的基础。Abstract: It has been reported that Oidium heveae triggers the disease resistance in model plant Arabidopsis thaliana in an Enhanced Disease Susceptibility 1 (EDS1) dependent manner, and EDS1 plays an important role in the signal pathway mediated by Toll-Interliukin 1 Receptor-nucleaotide binding-leucine-rich repeat (TIR-NB-LRR) type resistance genes. However, the upstream and downstream signaling of EDS1 is still unknown. In this study, A. thaliana Col-0 was inoculated with O. heveae HN1106, and we found the expression of ATAF2 gene, a member of plant NAC transcription factor family, was up-regulated 20 times after 4 days of inoculation as against 0 day of inoculation. Moreover, ATAF2 positively contributed to the disease resistance to O. heveae in A.thaliana. Furthermore, we found ATAF2 directly interacted with EDS1 in vitro and in vivo by GST pull-down and Co-immunoprecipitation assays, which lays a basis for the future study of EDS1 mediated resistance pathway.
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Key words:
- ATAF2 /
- EDS1 /
- Arabidopsis /
- Oidium heveae /
- Resistance
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