Identification of a small set of genes commonly regulated in rice roots in response to beneficial rhizobacteria

Abstract

Rhizosphere bacteria, whether phytopathogenic or phytobeneficial, are thought to be perceived by the plant as a threat. Plant Growth-Promoting Rhizobacteria (PGPR), such as many strains of the Azospirillum genus known as the main phytostimulator of cereals, cooperate with host plants and favorably affect their growth and health. An earlier study of rice root transcriptome, undertaken with two rice cultivars and two Azospirillum strains, revealed a strain-dependent response during the rice-Azospirillum association and showed that only a few genes, including some implicated in plant defense, were commonly regulated in all tested conditions. Here, a set of genes was selected from previous studies and their expression was monitored by qRT-PCR in rice roots inoculated with ten PGPR strains isolated from various plants and belonging to various genera (Azospirillum, Herbaspirillum, Paraburkholderia). A common expression pattern was highlighted for four genes that are proposed to be markers of the rice-PGPR interaction: two genes involved in diterpenoid phytoalexin biosynthesis (OsDXS3 and OsDTC2) and one coding for an uncharacterized protein (Os02g0582900) were significantly induced by PGPR whereas one defense-related gene encoding a pathogenesisrelated protein (PR1b, Os01g0382000) was significantly repressed. Interestingly, exposure to a rice bacterial pathogen also triggered the expression of OsDXS3 while the expression of Os02g0582900 and PR1b was downregulated, suggesting that these genes might play a key role in rice-bacteria interactions. Integration of these results with previous data led us to propose that the jasmonic acid signaling pathway might be triggered in rice roots upon inoculation with PGPR.

Symbiotic compatibility between rice cultivars and arbuscular mycorrhizal fungi genotypes affects rice growth and mycorrhiza-induced resistance

“…The expression of defence-related genes was recorded to assess how mycorrhization affects the defence response in healthy leaves. OsPR5 is a pathogenesis-related protein, OsPAL4 is a broad-spectrum disease resistance-related gene and OsTGAP1 & OsDXS3 are responsible for phytoalexines production in rice ( Okada et al., 2009 ; Delteil et al., 2012 ; Petitot et al., 2017 ; Valette et al., 2020 ). OsMPK10 and OsWRKY30 are responsible for early disease-mediated signalling, the latter also responsive to SA and JA treatments ( Ryu et al., 2006 ; Nguyễn et al., 2014 ).…”

A laudable strategy to manage bacterial panicle blight disease of rice using biocontrol agents

“…This interaction involves plant defense responses that react to the signal (elicitors) sent by the BCA. Various BCA's signaling compounds, including siderophores, lipopeptides, and volatile organic compounds have been suggested able to act as ISR elicitors [11,59,61] that commonly further mediated jasmonic acid (JA) signaling pathways in plants [79]. The activation of JA signaling pathway leads to defense-related compound secretion.…”

Current Techniques to Study Beneficial Plant-Microbe Interactions

“…Since hydroxycinnamic acid-based molecules are known to modulate plant defense, these workers decided to inoculate plants with the rice pathogen Burkholderia glumae AU6208, to study its impact on the synthesis of HCA derivatives. The results obtained highlighted the fact that plant inoculation with a pathogen, differently from what was observed after PGPB inoculation, leads to a lower accumulation of HCA derivatives suggesting the ability of the plant to perceive the colonization by a plant beneficial bacterium versus a plant deleterious one through the up or down accumulation of these HCA molecules [ 90 ].…”