Phytostimulation of drought stressed Arabidopsis by B. phytofirmans PsJN results from an interplay among contact-dependent induction of stress tolerance and volatile-mediated plant growth promotion
T. LEDGER (1), J. Tamayo (1), S. Rojas (1), J. Poupin (2) (1) Universidad Adolfo Ibáñez, Chile; (2) Universidad Adolfo Ibáñez, Chile

Plant growth promoting rhizobacteria (PGPR) can improve plant growth in the presence of drought stress. Burkholderia phytofirmans PsJN is a well-studied PGPR, reported to stimulate growth of different plant hosts. We have shown that PsJN increases growth and drought tolerance of Arabidopsis thaliana, improving biomass yield under low irrigation. However, the actual bacterial functions involved are yet unclear. The aim of this work was to differentiate the effects of plant bacteria contact-dependent functions, from those of bacterial emission of volatile compounds on the physiological response of A. thaliana to strain PsJN. To do this, plants were directly inoculated with live bacterial cells, with dead PsJN, or treated with volatile emissions from the bacterium. Then, seedlings were subjected to short and long term drought stress conditions and plant viability, water content, and ion-leakage were determined for each experimental group. Additionally, qRT-PCR analyses were performed to assess expression of ABA-dependent and -independent plant drought response pathways. The results of this work indicate that plant growth acceleration under drought in response to PsJN can be mainly attributed to volatile emission by live bacterial cells, while short-term stress tolerance, which reduces ion leakage and activates ABA-independent drought signaling, is dependent on direct contact of the plants with live or dead PsJN. FONDECYT 11121515, CAPES FB-0002-2014, Millenium Nucleus NC130030.

Abstract Number: P8-229
Session Type: Poster