英國、德國,、瑞士三國科學(xué)家近日通過研究,，揭示了病菌如何征服植物的防御系統(tǒng)。研究人員表示,，理解病菌入侵植物的機制將能幫助科學(xué)家研發(fā)出新的對抗植物疾病的方法,，而無需使用對人體和環(huán)境有害的殺蟲劑。相關(guān)論文12月4日在線發(fā)表于《當(dāng)代生物學(xué)》（Current Biology）,。
英國倫敦帝國理工學(xué)院生命科學(xué)系的John Mansfield和德國,、瑞士的合作者一起,，以模式植物擬南芥為實驗對象，檢查了其感染細(xì)菌性斑點病后分子水平上的變化,。研究人員發(fā)現(xiàn),，病菌向擬南芥細(xì)胞注入了一種蛋白，滅活并破壞了細(xì)胞表面的受體,，而這些受體的作用是在病菌入侵時向植物發(fā)出警報,。這就像是盜賊入室盜竊前摘除防盜警報一樣。
通常情況下,，細(xì)胞表面受體會發(fā)動連鎖反應(yīng),，產(chǎn)生抗菌化合物，殺滅入侵病菌,。而受體的失活則從起始階段停止了植物的防御機制,。
Mansfield表示：“受體一旦被破壞，植物的防御就會不起作用,，病菌從而能夠快速傳播,，吞食植物，遇不到絲毫的抵抗,。”
他說：“除了黑斑病之外,，這一領(lǐng)域的研究還具有更加廣泛的意義，因為所有致植物生病的細(xì)菌可能采取了相同的攻擊策略,，來抑制植物的抵抗,。我們對于致病菌如何征服農(nóng)作物的先天免疫了解得越多，就越有可能開發(fā)出新的疾病控制方法,，而無需使用具潛在危害的殺蟲劑,。”（生物谷Bioon.com）
生物谷推薦原始出處：
Current Biology，doi:10.1016/j.cub.2008.10.063,，John W. Mansfield,，Silke Robatzek
Plant Pattern-Recognition Receptor FLS2 Is Directed for Degradation by the Bacterial Ubiquitin Ligase AvrPtoB
Vera G?hre1,Thomas Spallek1,Heidrun H?weker1,Sophia Mersmann1,Tobias Mentzel2,Thomas Boller2,Marta de Torres3,4,John W. Mansfield3andSilke Robatzek1,,
1 Max-Planck-Institute for Plant Breeding Research, Carl-von-Linne-Weg 10, 50829 Cologne, Germany
2 Zurich-Basel Plant Science Center, University Basel, Hebelstrasse 1, 4056 Basel, Switzerland
3 Imperial College London, Division of Biology, South Kensington Campus, London SW7 2AZ, UK
SUMMARY
An important layer of active defense in plant immunity is the detection of pathogen-associated molecular patterns (PAMPs) mediated by cell-surface receptors. For the establishment of disease, pathogens depend on the ability to overcome PAMP perception and disable plant signaling pathways activated in response to PAMPs. Pattern recognition receptors (PRRs) are therefore prime targets for pathogen effectors. FLS2, its coreceptor BAK1, and EFR encode receptor-like kinases that play a role in immunity against bacterial pathogens.Here, we report that virulence of Pseudomonas syringae pv tomato DC3000 (PtoDC3000) in Arabidopsis is enhanced through the action of its effector AvrPtoB, which promotes degradation of FLS2. We show that AvrPtoB, through its N terminus, associates with FLS2 and BAK1, of which interaction with FLS2 is enhanced by flg22 activation. In vitro, AvrPtoB is active as an E3 ligase to catalyze polyubiquitination of the kinase domain of FLS2, a process confirmed in planta. Full enhancement of PtoDC3000 virulence appears to require the E3 ligase activity of AvrPtoB.AvrPtoB, initially identified through its activation of hypersensitive resistance in tomato cultivars expressing the Pto kinase, is composed of at least two functional domains: the N terminus is responsible for interaction with Pto, and the C terminus carries an E3 ligase activity. Based on our findings, we propose that both domains of AvrPtoB act together to support the virulence of PtoDC3000 in Arabidopsis through their ability to eliminate FLS2 from the cell periphery, and probably also other PAMP sensors that are constitutively expressed or induced after pathogen challenge.
