Visualizing the relevance of bacterial blue‐ and red‐light receptors during plant–pathogen interaction. Issue 5 (7th August 2015)

• Record Type: Journal Article
• Authors: Ricci, Ada; Dramis, Lucia; Shah, Rashmi; Gärtner, Wolfgang; Losi, Aba
• Is Part Of: Environmental microbiology reports. Volume 7:Issue 5(2015)
• Page Start: 795
• Page End: 802
• Publication Date: 2015-08-07
• Subjects: Microbial ecology -- Periodicals; Environmental Microbiology -- Periodicals; Electronic journals; 579.17
• DOI: 10.1111/1758-2229.12320
• Languages: English
• ISSNs: 1758-2229

Abstract

<abstract abstract-type="main"> <title>Summary</title> <p>The foliar pathogen <italic>P</italic><italic>seudomonas syringae</italic> pv. <italic>tomato</italic> DC3000 (<italic>P</italic><italic>st</italic>) leads to consistent losses in tomato crops, urging to multiply investigations on the physiological bases for its infectiveness. As other <italic>P</italic><italic>. syringae</italic> pathovars, <italic>P</italic><italic>st</italic> is equipped with photoreceptors for blue and red light, mimicking the photosensing ability of host plants. In this work we have investigated <italic>P</italic><italic>st</italic> strains lacking the genes for a blue‐light sensing protein (<italic>Pst</italic>LOV), for a bacteriophytochrome (<italic>P</italic><italic>st</italic>Bph1) or for heme‐oxygenase‐1. When grown in culturing medium, all deletion mutants presented a larger growth than wild‐type (WT) <italic>P</italic><italic>st</italic> under all other light conditions, with the exception of blue light which, under our experimental conditions (photon fluence rate = 40 μmol m<sup>−2</sup> s<sup>−1</sup>), completely suppressed the growth of the deletion mutants. Each of the knockout mutants shows stronger virulence towards <italic>A</italic><italic>rabidopsis thaliana</italic> than <italic>Pst</italic>WT, as evidenced by macroscopic damages in the host tissues of infected leaves. Mutated bacteria were also identified in districts distant from the infection site using scanning electron microscopy. These results underscore the importance of <italic>P</italic><italic>st</italic> photoreceptors in responding to environmental light inputs and the partial protective role that they exert towards host plants during infection, diminishing virulence and invasiveness.</p> </abstract>