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

Abstract

The signaling pathways induced by Pseudomonas putida in rice plants at the early plant–rhizobacteria interaction stages, with and without inoculation of Xanthomonas oryzae pv. oryzae, were studied. In the absence of pathogen, P. putida reduced ethylene (ET) production, and promoted root and stem elongation. Interestingly, gene OsHDA702, which plays an important role in root formation, was found significantly up-regulated in the presence of the rhizobacterium. Although X. oryzae pv. oryzae inoculation enhanced ET production in rice plants, P. putida 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 OsHDA705 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 OsHDA705 signaling.

Pseudomonas putida and its close relatives: mixing and mastering the perfect tune for plants

“…The role of gibberellins under saline conditions is also associated with mitigating the deleterious effects of salt stress by increasing water availability to plants (Colebrook et al 2014 ). Recently, it was reported that inoculation of rice plants with P. putida KT2440 stimulates an alternative plant defense mechanism based on abscisic acid accumulation (Wang et al 2020a , b ).…”

“…The best studied Pseudomonas PGPR strains include the P. fluorescens complex (including P. protegens , P. chlororaphis , P. brassicacearum , and P. koreensis ) (Ashraf et al 2019 ; Kang et al 2021 ; Wang et al 2020a , b ; Zhang et al 2020 ), P. stutzeri (Lami et al 2020 ), and P. putida (Costa-Gutierrez et al 2020a ; 2020b ). Despite the large number of reviews about Pseudomonas strains (e.g., Bhimeshwari et al 2018 ; Nadeem et al 2016 ; Shaikh et al 2020 ), the role of P. putida as a plant growth promoter has been neglected in the literature.…”

Endophytic bacteria: a possible path towards a sustainable agriculture

“…Normally, endophytic bacteria can initiate ISR using pathways mediated by salicylic acid, jasmonic acid, and ethylene (Yanti et al, 2019). Salicylic acid signaling positively regulates plant defense against biotrophic plant pathogenic fungi, whereas jasmonic acid and ethylene pathways are commonly required for resistance to necrotrophic plant pathogenic fungi and pests (Wang et al, 2020a). However, endophytic bacteria can use distinct plant defense signaling pathways, depending on the type of phytopathogen invader, that is, the same bacterium could use different pathways to confer resistance to different pathogens (Afzal et al, 2019).…”