Glycolate oxidase-dependent H2O2 production regulates IAA biosynthesis in rice

Xiangyang Li,Zhanqiao Lin,Nenghui Ye,Xinxiang Peng,Zhisheng Zhang,Mengmeng Liao,Jiayu Huang,Zheng Xu

doi:10.1186/s12870-021-03112-4

Xiangyang Li, Zhanqiao Lin + Show 6 more

Open Access

https://doi.org/10.1186/s12870-021-03112-4

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Abstract

BackgroundGlycolate oxidase (GLO) is not only a key enzyme in photorespiration but also a major engine for H2O2 production in plants. Catalase (CAT)-dependent H2O2 decomposition has been previously reported to be involved in the regulation of IAA biosynthesis. However, it is still not known which mechanism contributed to the H2O2 production in IAA regulation.ResultsIn this study, we found that in glo mutants of rice, as H2O2 levels decreased IAA contents significantly increased, whereas high CO2 abolished the difference in H2O2 and IAA contents between glo mutants and WT. Further analyses showed that tryptophan (Trp, the precursor for IAA biosynthesis in the Trp-dependent biosynthetic pathway) also accumulated due to increased tryptophan synthetase β (TSB) activity. Moreover, expression of the genes involved in Trp-dependent IAA biosynthesis and IBA to IAA conversion were correspondingly up-regulated, further implicating that both pathways contribute to IAA biosynthesis as mediated by the GLO-dependent production of H2O2.ConclusionWe investigated the function of GLO in IAA signaling in different levels from transcription, enzyme activities to metabolic levels. The results suggest that GLO-dependent H2O2 signaling, essentially via photorespiration, confers regulation over IAA biosynthesis in rice plants.

Highlights

Glycolate oxidase (GLO) is a key enzyme in photorespiration and a major engine for H 2O2 production in plants
Western blot analysis confirmed that GLO1 and GLO4 were absent in the glo1 and glo4 knockout mutants, respectively (Additional file 1A, B)
Our present results suggest that GLO-dependent H2O2 regulates Indole3-acetic acid (IAA) levels in rice, supporting the results from the Arabidopsis cat2 mutants [13, 14], and providing direct evidence that the CAT-dependent H 2O2 comes from the GLO-catalyzed reaction, essentially via photorespiratory metabolism in plants

Summary

Introduction

Glycolate oxidase (GLO) is a key enzyme in photorespiration and a major engine for H 2O2 production in plants. ABA regulates the expression of peroxisomal CAT and the levels of H 2O2 in water-stressed Arabidopsis [12] Another potential point of crosstalk is between the CAT-dependent H2O2 and IAA signaling pathway, which has recently gained much attention. Yuan et al [15] further demonstrated that the accumulated H2O2 in Arabidopsis resulting from CAT2 inhibition promoted the sulfenic acid modification of tryptophan synthetase β (TSB) subunit 1, subsequently decreasing TSB activity to repress the synthesis of the IAA precursor Trp. While CATdependent H2O2 decomposition intertwined with the IAA signaling pathway, the molecular details of this process remain scarce, and more notably, it is not clear whether GLO dependent H 2O2 production plays a major role in IAA regulation

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