植物在整個生長發(fā)育過程中經(jīng)受了各種病原菌的侵襲,，植物經(jīng)過與病原菌的長期共進(jìn)化形成了一套復(fù)雜的防御體系,。在整個植物與病原微生物互作過程中，多種植物激素（如水楊酸,、乙烯和茉莉酸等）發(fā)揮著十分重要的調(diào)控功能,。不同的植物激素介導(dǎo)不同的植物與病原微生物互作信號途徑，并有針對性地調(diào)控植物應(yīng)對不同類型病原菌的侵染,，比如水楊酸主要調(diào)控植物抵抗活體營養(yǎng)型病原菌的侵染,；茉莉酸和乙烯主要介導(dǎo)死體營養(yǎng)型病原菌的侵染，并在植物與病原微生物互作過程中常常表現(xiàn)出拮抗作用,。
目前已有大量的研究證實,，植物WRKY基因家族在植物與病原微生物互作信號途徑中發(fā)揮重要的生物學(xué)功能，但其相互作用的分子機制尚不很清楚,。近期,，中國科學(xué)院西雙版納熱帶植物園植物分子生物學(xué)研究組余迪求研究員的博士研究生陳利鋼通過潛心分析，系統(tǒng)解釋了擬南芥WRKY8基因如何參與調(diào)控植物與病原微生物互作反應(yīng)的分子機制及其信號通路,。其主要研究結(jié)果如下：（1）通過表達(dá)分析發(fā)現(xiàn),，擬南芥WRKY8基因受病原微生物PstDC3000和Botrytis誘導(dǎo)表達(dá)，在調(diào)控擬南芥抵抗病原微生物PstDC3000和Botrytis侵染中發(fā)揮重要的生物學(xué)功能,。（2）wrky8基因突變體提高了對活體營養(yǎng)型病原菌PstDC3000的抗性水平,，但降低了對死體營養(yǎng)型病原菌Botrytis的抗性水平；與之相反,，高表達(dá)WRKY8基因植株對PstDC3000的抗性水平降低,，而對Botrytis的抗性水平提高；（3）通過進(jìn)一步檢測抗病相關(guān)基因的表達(dá)發(fā)現(xiàn),，wrky8基因突變導(dǎo)致受水楊酸調(diào)控的PR1基因表達(dá)提高,，從而增強了抵抗PstDC3000侵染的抗性水平；同時通過抑制受茉莉酸調(diào)控的PDF1.2基因的表達(dá),，從而增加了對Botrytis侵染的敏感性,。以上研究結(jié)果表明，擬南芥WRKY8基因在水楊酸信號途徑中起負(fù)調(diào)控作用,，在茉莉酸途徑中起正調(diào)控作用,。
擬南芥WRKY8作為轉(zhuǎn)錄調(diào)控因子在不同類型的病原菌抗性中所具有的這種相反的生物學(xué)功能，說明抗病信號傳遞也發(fā)生在轉(zhuǎn)錄調(diào)控水平上,。此外,，更多參與這種相互拮抗調(diào)控的功能基因的發(fā)現(xiàn)和鑒定,，將有助于科學(xué)家詳盡闡明不同信號途徑之間的拮抗機制。
該項研究得到國家自然科學(xué)基金的資助,，相關(guān)研究成果已在國際著名學(xué)術(shù)刊物Molecular Plant-Microbe Interactions上發(fā)表,。(生物谷Bioon.com)
生物谷推薦原文出處：
Molecular Plant-Microbe Interactions DOI: 10.1094/MPMI-23-5-0558
Wounding-Induced WRKY8 Is Involved in Basal Defense in Arabidopsis
Ligang Chen,1,2 Liping Zhang,1,2 and Diqiu Yu1
1Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan 666303, China; 2The Graduate School of the Chinese Academy of Sciences, Beijing 100049, China
The WRKY family of plant transcription factors controls several types of plant stress responses. Arabidopsis WRKY8, localized to the nucleus, is mainly induced by abscissic acid, H2O2, wounding, Pseudomonas syringae and Botrytis cinerea infection, and aphid and maggot feeding. To determine its biological functions, we isolated loss-of-function T-DNA insertion mutants and generated gain-of-function overexpressing WRKY8 transgenic plants in Arabidopsis. Plants expressing the mutated WRKY8 gene showed increased resistance to P. syringae but slightly decreased resistance to B. cinerea. In contrast, transgenic plants overexpressing WRKY8 were more susceptible to P. syringae infection but more resistant to B. cinerea infection. The contrasting responses to the two pathogens were correlated with opposite effects on pathogen-induced expression of two genes; salicylic acid-regulated PATHOGENESIS-RELATED1 (PR1) and jasmonic acid-regulated PDF1.2. Therefore, our results suggest that WRKY8 is a negative regulator of basal resistance to P. syringae and positive regulator to B. cinerea.
