<i>Pseudomonas putida</i> Represses JA- and SA-Mediated Defense Pathways in Rice and Promotes an Alternative Defense Mechanism Possibly through ABA Signaling

• Main Authors: Rui Wang, Hai-Lin Wang, Rui-Ping Tang, Meng-Ying Sun, Tang-Min Chen, Xu-Chu Duan, Xiao-Feng Lu, Dong Liu, Xin-Chi Shi, Pedro Laborda, Su-Yan Wang
• Format: Article
• Language: English
• Published: MDPI AG 2020-11-01
• Series: Plants
• Subjects: <i>Oryza sativa</i>; plant growth-promoting rhizobacteria; plant–rhizobacteria interaction; plant defense; abscisic acid
• Online Access: https://www.mdpi.com/2223-7747/9/12/1641

The signaling pathways induced by <i>Pseudomonas putida</i> in rice plants at the early plant–rhizobacteria interaction stages, with and without inoculation of <i>Xanthomonas oryzae</i> pv. <i>oryzae</i>, were studied. In the absence of pathogen, <i>P. putida</i> reduced ethylene (ET) production, and promoted root and stem elongation. Interestingly, gene <i>OsHDA702</i>, which plays an important role in root formation, was found significantly up-regulated in the presence of the rhizobacterium. Although <i>X. oryzae</i> pv. <i>oryzae</i> inoculation enhanced ET production in rice plants, <i>P. putida</i> treatment repressed ET-, jasmonic acid (JA)- and salicylic acid (SA)-mediated defense pathways, and induced the biosynthesis of abscisic acid (ABA), and the overexpression of <i>OsHDA705</i> and some pathogenesis-related proteins (PRs), which in turn increased the susceptibility of the rice plants against the pathogen. Collectively, this is the first work on the defense signaling induced by plant growth-promoting rhizobacteria in plants at the early interaction stages, and suggests that rhizobacteria stimulate an alternative defense mechanism in plants based on ABA accumulation and <i>OsHDA705</i> signaling.