Euphorbiaceae superoxide dismutase, catalase, and glutathione peroxidase as clues to better comprehend high drought tolerance in castor bean

Superoxide dismutase (SOD), Catalase (CAT), and Glutathione peroxidase (GPX) enzymes exert a central role in reactive oxygen species (ROS) scavenger in plants, being an important part of enzymatic antioxidant system. Despite the importance of these enzymes in ROS metabolism and in different signaling pathways related to plant development and stress response, their gene families have not yet been comprehensively characterized in many crop plants. Among different crops, the Euphorbiaceae family has some species highly tolerant to drought stress. However, the gene families that encode the antioxidant enzymes, as well as their role in this drought stress tolerance, remains not characterized. Here, the SOD, CAT, and GPX genes of castor bean (Ricinus communis), cassava (Manihot esculenta), jatropha (Jatropha curcas), rubber tree (Hevea brasiliensis), petty spurge (Euphorbia peplus), and annual mercury (Mercurialis annua) were identified and characterized. The comprehensive phylogenetic and genomic analyses allowed the classification of the genes into different classes and revealed the duplication events that contribute to the expansion of these families within plant genomes. The expression patterns of SOD, CAT, and GPX genes were examined in castor bean, cassava, jatropha, and rubber tree by RNAseq analysis revealing differential expression during stress. Additionally, the castor bean gene expression was confirmed by RT-qPCR. Among castor bean genes, RcGPX4 appears to be induced in castor bean roots under drought stress, but the heterologous expression in Arabidopsis thaliana does not improve the drought tolerance. Altogether, this data has significantly contributed to characterizing the expression patterns and conducting evolutionary assessment of these genes in Euphorbiaceae. This bridge a gap in understanding the proposed functions of core components within the antioxidant mechanism in an economically significant group of plants, particularly during stress responses