Dynamic and fluctuating generation of hydrogen peroxide via photorespiratory metabolic channeling in plants

Abstract

SUMMARY The homeostasis of hydrogen peroxide (H2O2), a key regulator of basic biological processes, is a result of the cooperation between its generation and scavenging. However, the mechanistic basis of this balance is not fully understood. We previously proposed that the interaction between glycolate oxidase (GLO) and catalase (CAT) may serve as a molecular switch that modulates H2O2 levels in plants. In this study, we demonstrate that the GLO–CAT complex in plants exists in different states, which are dynamically interchangeable in response to various stimuli, typically salicylic acid (SA), at the whole‐plant level. More crucially, changes in the state of the complex were found to be closely linked to peroxisomal H2O2 fluctuations, which were independent of the membrane‐associated NADPH oxidase. Furthermore, evidence suggested that H2O2 channeling occurred even in vitro when GLO and CAT worked cooperatively. These results demonstrate that dynamic changes in H2O2 levels are physically created via photorespiratory metabolic channeling in plants, and that such H2O2 fluctuations may serve as signals that are mechanistically involved in the known functions of photorespiratory H2O2. In addition, our study also revealed a new way for SA to communicate with H2O2 in plants.

Wounding induces a peroxisomal H2O2 decrease via glycolate oxidase‐catalase switch dependent on glutamate receptor‐like channel‐supported Ca2+ signaling in plants

“…Local wounding induces a decrease in peroxisomal H 2 O 2 via GC switch in systemic leaves, in contrast to an outburst derived from RBOH GOX1, GOX2, and CAT2 are the key enzymes involved in photorespiration in Arabidopsis, corresponding to the isoforms GLO1, GLO4, and CATC in rice (Kerchev et al, 2016;Li et al, 2021). Also, similar to the GLO-CAT complex in rice, Arabidopsis GOXs interact with CAT and rapidly dissociate in response to SA (Figure S1) (Li et al, 2022), suggesting that the GC switch may exist commonly in plants.…”

“…The photorespiratory H 2 O 2 mainly modulates peroxisomal E GSH (per‐ E GSH ) without obvious influence on NADP(H) and ascorbate status (Chaouch & Noctor, 2010; Han et al., 2013; Noctor et al., 2002; Queval et al., 2007; Zhang et al., 2020). Hence, roGFP2 fused with peroxisomal target signal 1 (SKL) has been used as a proxy for the detection of photorespiratory H 2 O 2 dynamics (Li et al., 2022; Shibata et al., 2014; Yang et al., 2018). In addition, it is well established that the split‐luciferase complementation (split‐LUC) assay can powerfully pinpoint transient and reversible protein–protein interactions under native conditions by bringing the two separate luciferase tags together to transiently and proportionally reconstitute an active luciferase (Zhang & Fernie, 2021).…”

“…In addition, it is well established that the split‐luciferase complementation (split‐LUC) assay can powerfully pinpoint transient and reversible protein–protein interactions under native conditions by bringing the two separate luciferase tags together to transiently and proportionally reconstitute an active luciferase (Zhang & Fernie, 2021). Accordingly, we previously constructed a visualization tool plant GCR‐ Arabidopsis using rice GLO1 and CATC, which can synchronously or independently monitor the states of the GC switch (based on the split‐LUC assay) and/or peroxisomal H 2 O 2 dynamics at the whole‐plant level (based on roGFP2‐SKL) (Li et al., 2022). Interestingly, wounding of a local (“L”) leaf with scissors, which largely simulates grazing by herbivores (Toyota et al., 2018), induced a rapid shift of the GC switch to a more interactive state in systemic (“S”) leaves within minutes, which was more pronounced in younger leaves.…”

“…These results indicate a rapid response of the GC switch to mechanical wounding. Since the GC switch‐modulated dynamics of photorespiratory H 2 O 2 occur in peroxisomes (Li et al., 2022), two peroxisome‐specific H 2 O 2 reporter genes, HSP17 (At1g59860) and SAP12 (At3g28210), were used to detect changes in peroxisomal H 2 O 2 (Li et al., 2021; Sewelam et al., 2014; Siddiqui et al., 2020). The results showed that once the “L” leaf was wounded, expression levels of these two genes in “S” leaves decreased within 12 min.…”

“…By fluo‐4/AM staining and transiently expressing GCaMP3‐SKL in plant cells, respectively, it was observed that [Ca 2+ ] per levels increased following exogenous administration of the apoplastic Ca 2+ , and LaCl 3 treatment inhibited the increase (Figure 5a–c; Figure S14a–c). Considering the GC switch may generally exist in plans (Li et al., 2022; Figure S1), the recombinant His‐CATC and glutathione S‐transferase (GST)‐GLO1 were next employed as proxies to performed in vitro pull‐down assay. The result showed that Ca 2+ directly shifted the GC switch to a more interactive state.…”