The bacterial effector DspA/E is toxic in Arabidopsis thaliana and is required for multiplication and survival of fire blight pathogen. (12th March 2013)

• Record Type: Journal Article
• Authors: Degrave, Alexandre; Moreau, Manon; Launay, Alban; Barny, Marie‐Anne; Brisset, Marie‐Noëlle; Patrit, Oriane; Taconnat, Ludivine; Vedel, Regine; Fagard, Mathilde
• Is Part Of: Molecular plant pathology. Volume 14:Number 5(2013:Jun.)
• Page Start: 506
• Page End: 517
• Publication Date: 2013-03-12
• Subjects: Plant diseases -- Molecular aspects -- Periodicals; Plant-pathogen relationships -- Molecular aspects -- Periodicals; 571.936
• DOI: 10.1111/mpp.12022
• Languages: English
• ISSNs: 1464-6722

Abstract

<abstract abstract-type="main"> <title>Summary</title> <p>The type III effector DspA/E is an essential pathogenicity factor of the phytopathogenic bacterium <italic>Erwinia amylovora</italic>. We showed that DspA/E was required for transient bacterial growth in nonhost <italic>Arabidopsis thaliana</italic> leaves, as an <italic>E. amylovora dspA/E</italic> mutant was unable to grow. We expressed DspA/E in <italic>A. thaliana</italic> transgenic plants under the control of an oestradiol‐inducible promoter, and found that DspA/E expressed <italic>in planta</italic> restored the growth of a <italic>dspA/E</italic> mutant. DspA/E expression in these transgenic plants led to the modulation by at least two‐fold of the expression of 384 genes, mostly induced (324 genes). Both induced and repressed genes contained high proportions of defence genes. DspA/E expression ultimately resulted in plant cell death without requiring a functional salicylic acid signalling pathway. Analysis of <italic>A. thaliana</italic> transgenic seedlings expressing a green fluorescent protein (GFP):DspA/E fusion indicated that the fusion protein could only be detected in a few cells per seedling, suggesting the degradation or absence of accumulation of DspA/E in plant cells. Consistently, we found that DspA/E repressed plant protein synthesis when injected by <italic>E. amylovora</italic> or when expressed in transgenic plants. Thus, we conclude that DspA/E is toxic to <italic>A. thaliana</italic>: it promotes modifications, among which the repression of protein synthesis could be determinant in the facilitation of necrosis and bacterial growth.</p> </abstract>