The effector protein Avr2 of the xylem-colonizing fungus Fusarium oxysporum activates the tomato resistance protein I-2 intracellularly.

TitleThe effector protein Avr2 of the xylem-colonizing fungus Fusarium oxysporum activates the tomato resistance protein I-2 intracellularly.
Publication TypeJournal Article
Year of Publication2009
AuthorsHouterman PM, Ma L, van Ooijen G, de Vroomen MJ, Cornelissen BJC, Takken FLW, Rep M
JournalThe Plant journal : for cell and molecular biology
Volume58
Issue6
Pagination970-8
Date Published2009 Jun
ISSN1365-313X
KeywordsAmino Acid Sequence, DNA, Fungal, Fungal Proteins, Fusarium, Gene Expression Regulation, Plant, Genetic Complementation Test, Immunity, Innate, Lycopersicon esculentum, Molecular Sequence Data, Plant Diseases, Plant Proteins, Plants, Genetically Modified, Point Mutation, Tobacco, Virulence
Abstract

To promote host colonization, many plant pathogens secrete effector proteins that either suppress or counteract host defences. However, when these effectors are recognized by the host's innate immune system, they trigger resistance rather than promoting virulence. Effectors are therefore key molecules in determining disease susceptibility or resistance. We show here that Avr2, secreted by the vascular wilt fungus Fusarium oxysporum f. sp. lycopersici (Fol), shows both activities: it is required for full virulence in a susceptible host and also triggers resistance in tomato plants carrying the resistance gene I-2. Point mutations in AVR2, causing single amino acid changes, are associated with I-2-breakingFol strains. These point mutations prevent recognition by I-2, both in tomato and when both genes are co-expressed in leaves of Nicotiana benthamiana. Fol strains carrying the Avr2 variants are equally virulent, showing that virulence and avirulence functions can be uncoupled. Although Avr2 is secreted into the xylem sap when Fol colonizes tomato, the Avr2 protein can be recognized intracellularly by I-2, implying uptake by host cells.

DOI10.1111/j.1365-313X.2011.04489.x
Alternate JournalPlant J.
PubMed ID19228334