Catalase (CAT) Gene Family in Rapeseed ( Brassica napus L.): Genome-Wide Analysis, Identification, and Expression Pattern in Response to Multiple Hormones and Abiotic Stress Conditions

Catalase (CAT) is an antioxidant enzyme expressed by the gene family and exists in almost all aerobic organisms. Environmental stresses induce the generation of reactive oxygen species (ROS) that eventually hinder plant growth and development. The CAT enzyme translates the hydrogen peroxide (H O ) to water (H O) and reduce the ROS levels to shelter the cells' death. So far, the gene family has not been reported in rapeseed ( L.). Therefore, a genome-wide comprehensive analysis was conducted to classify the genes in the rapeseed genome. The current study identified 14 genes in the rapeseed genome. Based on phylogenetic and synteny analysis, the belong to four groups (Groups I-IV). A gene structure and conserved motif analysis showed that Group I, Group II, and Group IV possess almost the same intron/exon pattern, and an equal number of motifs, while Group III contains diverse structures and contain 15 motifs. By analyzing the -elements in the promoters, we identified five hormone-correlated responsive elements and four stress-related responsive elements. Further, six putative bna-miRNAs were also identified, targeting three genes ( and ). Gene ontology (GO) enrichment analysis showed that the genes were largely related to cellular organelles, ROS response, stimulus response, stress response, and antioxidant enzymes. Almost 10 genes showed higher expression levels in different tissues, i.e., root, leaf, stem, and silique. The expression analysis showed that and were significantly upregulated by cold, salinity, abscisic acid (ABA), and gibberellic acid (GA) treatment, but not by drought and methyl jasmonate (MeJA). Notably, most of the genes were upregulated by waterlogging stress, except , and . Our results opened new windows for future investigations and provided insights into the family genes in rapeseed.