The Pseudomonas syringae type III effector AvrRpt2 functions downstream or independently of SA to promote virulence on Arabidopsis thaliana
The Pseudomonas syringae type III effector AvrRpt2 functions downstream or independently of SA to promote virulence on Arabidopsis thaliana
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DOI：
10.1111/j.1365-313x.2003.01984.x
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发表时间：
2004-02-01
期刊：
影响因子：
7.2
通讯作者：
Kunkel, BN
中科院分区：
文献类型：
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作者：
Chen, ZY;Kloek, AP;Kunkel, BN
AvrRpt2是丁香假单胞菌III型效应蛋白，在植物细胞内起促进丁香假单胞菌毒力的作用。番茄品系DC3000 （PstDC3000）在拟南芥植株上缺乏相应RPS2抗性基因的功能拷贝。在本研究中，我们通过探索AvrRpt2通过抑制植物防御来促进PstDC3000毒力的假设，扩展了我们对AvrRpt2毒力活性的理解。当通过PstDC3000传递时，AvrRpt2在感染过程中抑制病原体相关（PR）基因的表达，表明AvrRpt2抑制水杨酸（SA）介导的防御。然而，AvrRpt2在表达SA降解酶NahG的转基因植物上促进PstDC3000的生长，表明AvrRpt2在感染过程中不是通过调节SA水平来促进细菌毒力的。AvrRpt2的一般毒力活性不依赖于RPM1抗性基因，因为RPM1的突变对AvrRpt2诱导的表型没有影响。表达AvrRpt2的转基因植物对III型分泌缺陷的PstDC3000株的敏感性增强，表明这些植物的敏感性增强不是由于抑制了其他III型效应物引起的防御反应。此外，avrRpt2转基因植株对Peronospora parasitica和Erysiphe cichoracearum的敏感性没有增加，表明avrRpt2的毒力活性是针对丁香假单胞菌的。
AvrRpt2, a Pseudomonas syringae type III effector protein, functions from inside plant cells to promote the virulence of P. syringae pv. tomato strain DC3000 (PstDC3000) on Arabidopsis thaliana plants lacking a functional copy of the corresponding RPS2 resistance gene. In this study, we extended our understanding of AvrRpt2 virulence activity by exploring the hypothesis that AvrRpt2 promotes PstDC3000 virulence by suppressing plant defenses. When delivered by PstDC3000, AvrRpt2 suppresses pathogen-related (PR) gene expression during infection, suggesting that AvrRpt2 suppresses defenses mediated by salicylic acid (SA). However, AvrRpt2 promotes PstDC3000 growth on transgenic plants expressing the SA-degrading enzyme NahG, indicating that AvrRpt2 does not promote bacterial virulence by modulating SA levels during infection. AvrRpt2 general virulence activity does not depend on the RPM1 resistance gene, as mutations in RPM1 had no effect on AvrRpt2-induced phenotypes. Transgenic plants expressing AvrRpt2 displayed enhanced susceptibility to PstDC3000 strains defective in type III secretion, indicating that enhanced susceptibility of these plants is not because of suppression of defense responses elicited by other type III effectors. Additionally, avrRpt2 transgenic plants did not exhibit increased susceptibility to Peronospora parasitica and Erysiphe cichoracearum, suggesting that AvrRpt2 virulence activity is specific to P. syringae.