Dehydroascorbate induces plant resistance in rice against root‐knot nematode Meloidogyne graminicola

Abstract

Ascorbic acid (AsA) is an important antioxidant in plants and regulates various physiological processes. In this study, we show that exogenous treatments with the oxidized form of AsA, that is, dehydroascorbate (DHA), activates induced systemic resistance in rice against the root‐knot nematode Meloidogyne graminicola , and investigate the molecular and biochemical mechanisms underlying this phenotype. Detailed transcriptome analysis on roots of rice plants showed an early and robust transcriptional response on foliar DHA treatment, with induction of several genes related to plant stress responses, immunity, antioxidant activity, and secondary metabolism already at 1 day after treatment. Quantitative and qualitative evaluation of H 2 O 2 levels confirmed the appearance of a reactive oxygen species (ROS) burst on DHA treatment, both at the site of treatment and systemically. Experiments using chemical ROS inhibitors or scavengers confirmed that H 2 O 2 accumulation contributes to DHA‐based induced resistance. Furthermore, hormone measurements in DHA‐treated plants showed a significant systemic accumulation of the defence hormone salicylic acid (SA). The role of the SA pathway in DHA‐based induced resistance was confirmed by nematode infection experiments using an SA‐signalling deficient WRKY45 ‐RNAi line and reverse transcription‐quantitative PCR on SA marker genes. Our results collectively reveal that DHA activates induced systemic resistance in rice against the root‐knot nematode M. graminicola , mediated through the production of ROS and activation of the SA pathway.

Rice diterpenoid phytoalexins are involved in defence against parasitic nematodes and shape rhizosphere nematode communities

“…Transcriptional analysis of roots of rice seedlings revealed a notable induction of the DP biosynthetic pathway 24 h after PA treatment, the same time point at which plants were inoculated with M. graminicola (Table 1). Interestingly, an in‐house transcriptome dataset of plants at 1 d post treatment with DHA showed a similar induction of root DP biosynthesis (Chavan et al ., 2022).…”

Biocontrol potential of Pseudomonas rhodesiae GC-7 against the root-knot nematode Meloidogyne graminicola through both antagonistic effects and induced plant resistance

“…JaMYB and AOS2 are marker genes for JA-dependent signaling pathways, whereas ERF1 and ACS1 are markers of the ET signaling pathway ( Leonetti et al, 2017 ; Salman et al, 2022 ). Previous studies on rice have also shown that the exogenous application of plant hormones and antioxidants induces systemic defense against M. graminicola, and that the JA pathway plays a pivotal role in the induction of defense against RKN ( Nahar et al, 2011 ; Singh et al, 2020 ; Chavan et al, 2022 ). Conversely, abscisic acid (ABA), brassinosteroids (BRs), gibberellic acid, and strigolactones promote the susceptibility of rice to M. graminicola infection by interacting antagonistically with the JA pathway ( Nahar et al, 2012 ; Yimer et al, 2018 ; Lahari et al, 2019 ).…”

Distinct chemical resistance-inducing stimuli result in common transcriptional, metabolic, and nematode community signatures in rice root and rhizosphere

“…Roots from five seedlings were pooled to form one sample, and three pooled samples were created per treatment. Plants treated with BTH, BABA or PA, and their corresponding control plants, were grown by the author for this study; mRNA-seq on DHA-treated plants and their control plants was performed earlier (Chavan et al, 2022). The same growth chamber, light and temperature settings an batch of Kitaake seeds were used for both experiments.…”

“…In agreement with previously published results (Nahar et al, 2011;Ji et al, 2015;Singh et al, 2020;Desmedt et al, 2021a), pre-treatment with 3.5 mM β-aminobutyric acid (BABA), 300 µM piperonylic acid (PA), 250 µM benzothiadiazole (BTH) or 20 mM dehydroascorbic acid (DHA) reduces rice susceptibility to the root-knot nematode M. graminicola (Figure 1a). As previously shown, two applications of PA are required to induce full resistance (Desmedt et al, 2021a(Desmedt et al, , 2022; for this reason, further experiments were performed on plants treated with PA twice. BABA, BTH and PA caused no phytotoxicity and had no effect onplant growth (Figure 1b-c).…”

“…Most of this literature has focused on the interaction between rice and the rootknot nematode Meloidogyne graminicola, one of the most devastating pests of rice (Mantelin et al, 2017). Examples of chemical IR stimuli effective in this pathosystem include β-aminobutyric acid (BABA; Ji et al, 2015), acibenzolar-S-methyl/benzothiadiazole (BTH; Nahar et al, 2011), piperonylic acid (PA;Desmedt et al, 2021aDesmedt et al, , 2022, dehydroascorbic acid (DHA; Singh et al, 2020), thiamine (Huang et al, 2016) and diproline (De Kesel et al, 2020). Interestingly, most of these stimuli induce resistance to M. graminicola when applied to rice shoots.…”