Catalase (CAT) is an antioxidant enzyme expressed by the
CAT 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
2O
2) to water (H
2O) and reduce the ROS levels to shelter the cells’ death. So far, the
CAT gene family has not been reported in rapeseed (
Brassica napus L.). Therefore, a genome-wide comprehensive analysis was conducted to classify the
CAT genes in the rapeseed genome. The current study identified 14
BnCAT genes in the rapeseed genome. Based on phylogenetic and synteny analysis, the
BnCATs 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
cis-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 (
BnCAT4, BnCAT6, and
BnCAT8). Gene ontology (GO) enrichment analysis showed that the
BnCAT genes were largely related to cellular organelles, ROS response, stimulus response, stress response, and antioxidant enzymes. Almost 10
BnCAT genes showed higher expression levels in different tissues, i.e., root, leaf, stem, and silique. The expression analysis showed that
BnCAT1–BnCAT3 and
BnCAT11–BnCAT13 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
BnCAT6, BnCAT9, and
BnCAT10. Our results opened new windows for future investigations and provided insights into the
CAT family genes in rapeseed.
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