The Pseudomonas syringae type III effector AvrRpt2 functions downstream or independently of SA to promote virulence on Arabidopsis thaliana

被引:51
作者
Chen, ZY
Kloek, AP
Cuzick, A
Moeder, W
Tang, DZ
Innes, RW
Klessig, DF
McDowell, JM
Kunkel, BN
机构
[1] Washington Univ, Dept Biol, St Louis, MO 63130 USA
[2] Virginia Polytech Inst & State Univ, Fralin Biotechnol Ctr, Dept Plant Pathol Physiol & Weed Sci, Blacksburg, VA 24061 USA
[3] Boyce Thompson Inst Plant Res, Ithaca, NY 14853 USA
[4] Indiana Univ, Dept Biol, Bloomington, IN 47405 USA
关键词
Pseudomonas syringae; Arabidopsis; virulence; AvrRpt2; salicylic acid; NahG;
D O I
10.1111/j.1365-313X.2003.01984.x
中图分类号
Q94 [植物学];
学科分类号
071001 ;
摘要
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.
引用
收藏
页码:494 / 504
页数:11
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