Identification of glutathione peroxidase gene family in ricinus communis and functional characterization of RcGPX4 in cold tolerance

Authors: WANG, XIAOYU - Inner Mongolia University; LIU, XUMING - Inner Mongolia University; An, Yong-Qiang - Charles; ZHANG, HONGYU - Inner Mongolia University; MENG, DI - Inner Mongolia University; JIN, YANAN - Inner Mongolia University; HUO, HONGYAN - Inner Mongolia University; YU, LILI - Inner Mongolia University; ZHANG, JIXING - Inner Mongolia University

Submitted to: Frontiers in Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/30/2021
Publication Date: 11/5/2021
Citation: Wang, X., Liu, X., An, Y., Zhang, H., Meng, D., Jin, Y., Huo, H., Yu, L., Zhang, J. 2021. Identification of glutathione peroxidase gene family in ricinus communis and functional characterization of RcGPX4 in cold tolerance. Frontiers in Plant Science. 12. Article 707127. https://doi.org/10.3389/fpls.2021.707127.
DOI: https://doi.org/10.3389/fpls.2021.707127

Interpretive Summary: For crop improvement, it is critical to discover genes involved in plant tolerance to environmental stresses and understand their underlying molecular mechanism. Previous research suggests that a group of genes called glutathione peroxidases (GPXs) are likely involved in plant response to a variety of environmental stresses. To understand its underlying molecular mechanism for crop improvement, we characterized the DNA sequences of the GPX genes in different plant species and showed that they likely play similar functions. Production of a GPX gene called RcGPX4 in Arabidopsis plants enhanced cold tolerance at seed germination but reduced freezing tolerance for seedlings. The study also discovered additional genes and biological pathways that were involved in freezing tolerance. This research generated a suite of genes related to plant cold tolerance and provided insight into how RcGPX4 affect plant freezing tolerance, which is valuable for us to improve stress tolerance of economically important crops such as soybean.

Technical Abstract: Glutathione peroxidases (GPXs) protect cells against damage caused by reactive oxygen species (ROS) and play key roles in regulating many biological processes. Here, five GPXs were identified in the Ricinus communis genome. Phylogenetic analysis displayed that the GPXs were categorized into five groups. Conserved domain and gene structure analyses showed that the GPXs from different plant species harbored four highly similar motifs and conserved exon-intron arrangement patterns, indicating that their structure and function may have been conserved during evolution. Several abiotic stresses and hormone-responsive cis-acting elements existed in the promoters of the RcGPXs. The expression profiles indicated that the RcGPXs varied substantially, and some RcGPXs were coordinately regulated under abiotic stresses. Overexpression of RcGPX4 in Arabidopsis enhanced cold tolerance at seed germination but reduced freezing tolerance at seedlings. The expression of abscisic acid (ABA) signaling genes (AtABI4 and AtABI5), ABA catabolism genes (AtCYP707A1 and AtCYP707A2), gibberellin acid (GA) catabolism gene (AtGA2ox7), and cytokinin (CTK)-inducible gene (AtARR6) was regulated in the seeds of transgenic lines under cold stress. Overexpression of RcGPX4 can disturb the hydrogen peroxide (H2O2) homeostasis through the modulation of some antioxidant enzymes and compounds involved in the GSH-ascorbate cycle in transgenic plants. Additionally, RcGPX4 depended on the MAPK3-ICE1-C-repeat-binding factor (CBF)-COR signal transduction pathway and ABA-dependent pathway to negatively regulate the freezing tolerance of transgenic plants. This study provides valuable information for understanding the potential function of RcGPXs in regulating the abiotic stress responses of castor beans.