A single effector protein, AvrRpt2EA, from erwinia amylovora can cause fire blight disease symptoms and induces a salicylic acid-dependent defense response

Susan Schropfer, Christoph Bottcher, Thomas Wohner, Klaus Richter, John Norelli, Erik H.A. Rikkerink, Magda Viola Hanke, Henryk Flachowsky

Research output: Contribution to journalArticlepeer-review

19 Scopus citations

Abstract

The AvrRpt2EA effector protein of Erwinia amylovora is important for pathogen recognition in the fire blight-resistantcrabapple Malus × robusta 5; however, little is known aboutits role in susceptible apples. To study its function in planta, weexpressed a plant-optimized version of AvrRpt2EA driven by aheat shock-inducible promoter in transgenic plants of the fireblight-susceptible cultivar Pinova. After induced expressionof AvrRpt2EA, transgenic lines showed shoot necrosis and browning of older leaves, with symptoms similar to natural fire blightinfections. Transgenic expression of this effector protein resultedin an increase in the expression of the salicylic acid (SA)-responsive PR-1 gene but, also, in the levels of SA and its derivatives, with diverse kinetics in leaves of different ages. Incontrast, no increase of expression levels of VSP2 paralogs,used as marker genes for the activation of the jasmonic acid(JA)-dependent defense pathway, could be detected, which isin agreement with metabolic profiling of JA and its derivatives.Our work demonstrates that AvrRpt2EA acts as a virulence factor and induces the formation of SA and SA-dependent systemic acquired resistance.

Original languageEnglish
Pages (from-to)1179-1191
Number of pages13
JournalMolecular Plant-Microbe Interactions
Volume31
Issue number11
DOIs
StatePublished - Nov 2018
Externally publishedYes

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