Nine amino acids determine recognition of Verticillium dahliae effector Ave1 by tomato immune receptor Ve1.
Zhao Zhang1,2, Jordi C. Boshoven1, Karunakaran Maruthachalam3, Krishna V. Subbarao3, Chun-Ming Liu2 and Bart P.H.J. Thomma1,4*
1Laboratory of Phytopathology, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands.
2Key Laboratory of Plant Molecular Physiology, Institute of Botany, the Chinese Academy of Sciences, Beijing 100093, China.
3Department of Plant Pathology, University of California, Davis, CA 95616, USA.
4Centre for BioSystems Genomics, P.O. Box 98, 6700 AB Wageningen, The Netherlands.
*Author for correspondence: Bart P.H.J. Thomma, Laboratory of Phytopathology, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands. Tel. 0031-317-484536, Fax 0031-317-483412, e-mail: email@example.com
Effectors are molecules secreted by plant pathogens to facilitate infection, often by suppression of plant immune responses. During infection on its hosts, the soil-borne vascular wilt fungus Verticillium dahliae secretes effector protein Ave1 (for Avirulence on Ve1 tomato 1) that is recognized by the immune receptor Ve1 that is present in particular tomato genotypes. Although Ave1 unambiguously contributes to fungal virulence on susceptible tomato genotypes, the intrinsic function of Ave1 for fungal infection is not known yet. Interestingly, homologs of V. dahliae Ave1 (VdAve1), have been identified in the bacterial pathogen Xanthomonas axonopodis pv. citri as XacPNP, and in the fungal pathogens Fusarium oxysporum, Colletotrichum higginsianum and Cercospora beticola, as FoAve1, ChAve1 and CbAve1, respectively. By using agroinfiltration in tobacco, we found these Ave1 homologs are differentially recognized by Ve1. To determine the region of Ave1 that is recognized by Ve1, targeted deletions and domain swaps were generated, based on the alignment of differentially recognized Ave1 homologs. We show that the carboxyterminus of Ave1 determines the necrosis-inducing activity in Ve1 expressing plants. Interestingly, Ve1-mediated immunity can be induced by a nine amino acid sequence derived from the carboxyterminus of VdAve1.
Key Words: PAMP receptor; hypersensitive response (HR); Fusarium oxysporum; Xanthomonas axonopodis; Colletotrichum higginsianum; Cercospora beticola; XacPNP