Abscisic acid negatively modulates plant defence against rice black‐streaked dwarf virus infection by suppressing the jasmonate pathway and regulating reactive oxygen species levels in rice

Abstract

Abscisic acid (ABA) plays a multifaceted role in plant immunity and can either increase resistance or increase susceptibility to some bacterial and fungal pathogens depending on the pathosystem. ABA is also known to mediate plant defence to some viruses. In this study, the relationship between the ABA pathway and rice black-streaked dwarf virus (RBSDV) was investigated in rice. The expression of ABA pathway genes was significantly reduced upon RBSDV infection. Application of exogenous hormones and various ABA pathway mutants revealed that the ABA pathway plays a negative role in rice defence against RBSDV. Exogenous hormone treatment and virus inoculation showed that ABA inhibits the jasmonate-mediated resistance to RBSDV. ABA treatment also suppressed accumulation of reactive oxygen species by inducing the expression of superoxidase dismutases and catalases. Thus, ABA modulates the rice-RBSDV interaction by suppressing the jasmonate pathway and regulating reactive oxygen species levels. This is the first example of ABA increasing susceptibility to a plant virus.

Suppression of auxin signalling promotes rice susceptibility to Rice black streaked dwarf virus infection

“…However, ROS were shown to play vital roles in plant defence against rice viruses (Wu et al , ). Our previous results also showed that high basal ROS levels can enhance antiviral defence against RBSDV infection (Xie et al , ). Here, our results indicate that auxin can induce the expression of OsRboh and that disruption of auxin signalling decreased the expression of OsRboh .…”

“…It has recently been reported that accumulation of basal ROS plays an important role in antiviral immunity (Wu et al , ; Xie et al , ). In plants, NADPH oxidases (respiratory burst oxidase homologs, Rboh ) play key roles in generating ROS by catalysing the conversion of O 2 to superoxide (O 2 ‐ ) (Suzuki et al , ).…”

“…However, the interplay between auxin and ROS has been little reported in the context of plant defence. Recently, ROS were demonstrated to be involved in plant–virus interactions (Hyodo et al , ; Wu et al , ; Xie et al , ). Two positive‐strand RNA viruses, Red clover necrotic mosaic virus (RCNMV) and Brome mosaic virus , were shown to hijack the host's ROS‐generating machinery and trigger intracellular ROS bursts (Hyodo et al , ).…”

“…While the JA pathway played an important role in defence against RBSDV, the BR pathway facilitated infection (Zhang et al , ). In addition, the abscicic acid (ABA) pathway was also shown to negatively regulate plant defence against RBSDV (Xie et al , ).…”

Nitric Oxide Enhances Rice Resistance to Rice Black-Streaked Dwarf Virus Infection

“…For example, during RBSDV infection in rice, jasmonic acid (JA) production was found to be increased; whereas, brassinosteroid (BR) production, which is important for integrating salicylic acid (SA) pathway with jasmonic acid (JA) pathway, was suppressed (He et al 2017;Pan et al 2018). A recent study further showed that abscisic acid (ABA) could negatively regulate rice resistance to RBSDV infection (Xie et al, 2018).…”