New Study Reveals How Plants Sense H2O2 to Regulate Immunity

Hydrogen peroxide (H₂O₂) is a ubiquitous molecule in all aerobic organisms. At high concentrations, H₂O₂ causes oxidative stress, whereas at low concentrations, H₂O₂ serves as an important secondary signal to regulate numerous biological processes including, but not limited to, plant-microbe interactions, abiotic stress tolerance, pollen tube growth, root hair formation, leaf cell expansion and casparian strip formation. However, the endogenous H₂O₂ concentrations are too low to efficiently oxidize most target proteins, and it remains to be shown how plants sense endogenous H₂O₂ to regulate biological processes.

 

In a recent study published on Nature Plants (DOI:10.1038/s41477-022-01252-5), research group of Prof. ZHOU Jian-Min from the Institute of Genetics and Developmental Biology (IGDB), Chinese Academy of Sciences and their collaborators illustrate a redox relay, with peroxiredoxin B (PRXIIB) as a sensor for H₂O₂ and ABA insensitive 2 (ABI2) as a target protein, that mediate ROS signaling during plant immunity.  

 

The production of H₂O₂ is a hallmark of plant immune system and plays a critical role in plant immunity, such as stomatal closure to limit pathogen entry. To investigate mechanisms by which H₂O₂ regulates plant stomatal immunity, the research group performed mass-spectrometry-based analysis termed SulfenQ, and showed that type II PRXIIB was directly oxidized at its peroxidatic cysteine by H₂O₂ generated upon immune activation.

 

Furthermore, they showed that PRXIIB form disulfide-conjugates with ABI2, subsequently transducing H₂O₂ signal to ABI2. This oxidation dramatically sensitizes H₂O₂-mediated inhibition of the ABI2 phosphatase activity and is required for stomatal immunity in plants.

 

This study establishes the link between endogenous H₂O₂ sensing and biological functions, and the mechanisms described in this study may serve as a paradigm for similar researches in plant stress acclimation and development in the future.

 

Contact:

Dr. ZHOU Jian-Min

Institute of Genetics and Developmental Biology, Chinese Academy of Sciences