AUTHOR=Miotto-Vilanova Lidiane , Jacquard Cédric , Courteaux Barbara , Wortham Laurence , Michel Jean , Clément Christophe , Barka Essaïd A. , Sanchez Lisa 

TITLE=Burkholderia phytofirmans PsJN Confers Grapevine Resistance against Botrytis cinerea via a Direct Antimicrobial Effect Combined with a Better Resource Mobilization

JOURNAL=Frontiers in Plant Science

VOLUME=7

YEAR=2016

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2016.01236

DOI=10.3389/fpls.2016.01236

ISSN=1664-462X

ABSTRACT=<p>Plant innate immunity serves as a surveillance system by providing the first line of powerful weapons to fight against pathogen attacks. Beneficial microorganisms and Microbial-Associated Molecular Patterns might act as signals to trigger this immunity. <italic>Burkholderia phytofirmans</italic> PsJN, a highly efficient plant beneficial endophytic bacterium, promotes growth in a wide variety of plants including grapevine. Further, the bacterium induces plant resistance against abiotic and biotic stresses. However, no study has deciphered triggered-mechanisms during the tripartite interaction between grapevine, <italic>B. phytofirmans</italic> PsJN and <italic>Botrytis cinerea</italic>. Herein, we showed that in contrast with classical rhizobacteria, which are restricted in the root system and act through ISR, <italic>B. phytofirmans</italic> PsJN is able to migrate until aerial part and forms at leaves surface a biofilm around <italic>B. cinerea</italic> mycelium to restrict the pathogen. Nevertheless, considering the endophytic level of PsJN in leaves, the plant protection efficacy of <italic>B. phytofirmans</italic> PsJN could not be explained solely by its direct antifungal effect. Deeper investigations showed a callose deposition, H<sub>2</sub>O<sub>2</sub> production and primed expression of <italic>PR1, PR2, PR5</italic>, and <italic>JAZ</italic> only in bacterized-plantlets after pathogen challenge. The presence of PsJN modulated changes in leaf carbohydrate metabolism including gene expression, sugar levels, and chlorophyll fluorescence imaging after <italic>Botrytis</italic> challenge. Our findings indicated that protection induced by <italic>B. phytofirmans</italic> PsJN was multifaceted and relied on a direct antifungal effect, priming of defense mechanisms as well as the mobilization of carbon sources in grapevine leaf tissues.</p>