An NB‐LRR protein required for HR signalling mediated by both extra‐ and intracellular resistance proteins

作者：S.H.E.J. Gabriëls, Jack H. Vossen, Sophia Ekengren, Gerben van Ooijen, Ahmed Abd‐El‐Haliem, Grardy C. M. van den Berg, Daphne Y. Rainey, Gregory B. Martin, Frank L. W. Takken, P.J.G.M. de Wit, M.H.A.J. Joosten · 发表于：The Plant Journal · 年份：2007 · DOI：10.1111/j.1365-313x.2007.03027.x · 被引用次数：212 · 研究领域：Plant-Microbe Interactions and Immunity、Plant Pathogenic Bacteria Studies、Plant Virus Research Studies

Tomato (Solanum lycopersicum) Cf resistance genes confer hypersensitive response (HR)-associated resistance to strains of the pathogenic fungus Cladosporium fulvum that express the matching avirulence (Avr) gene. Previously, we identified an Avr4-responsive tomato (ART) gene that is required for Cf-4/Avr4-induced HR in Nicotiana benthamiana as demonstrated by virus-induced gene silencing (VIGS). The gene encodes a CC-NB-LRR type resistance (R) protein analogue that we have designated NRC1 (NB-LRR protein required for HR-associated cell death 1). Here we describe that knock-down of NRC1 in tomato not only affects the Cf-4/Avr4-induced HR but also compromises Cf-4-mediated resistance to C. fulvum. In addition, VIGS using NRC1 in N. benthamiana revealed that this protein is also required for the HR induced by the R proteins Cf-9, LeEix, Pto, Rx and Mi. Transient expression of NRC1(D481V), which encodes a constitutively active NRC1 mutant protein, triggers an elicitor-independent HR. Subsequently, we transiently expressed this auto-activating protein in N. benthamiana silenced for genes known to be involved in HR signalling, thereby allowing NRC1 to be positioned in an HR signalling pathway. We found that NRC1 requires RAR1 and SGT1 to be functional, whereas it does not require NDR1 and EDS1. As the Cf-4 protein requires EDS1 for its function, we hypothesize that NRC1 functions downstream of EDS1. We also found that NRC1 acts upstream of a MAP kinase pathway. We conclude that Cf-...