Superoxide dismutases (SOD), as a family of metalloenzymes related to the removal of reactive oxygen species (ROS), have not previously been investigated at the whole genome level in the tea plant. In this study, 10 CsSOD genes were identified in the tea plant genome, including 7 Cu / Zn-SOD (CSD), 2 Fe-SOD (FSD), and one Mn-SOD (MSD), and were phylogenetically classified into three subgroups, respectively. Analysis of physicochemical characteristics, conserved motifs and potential protein interaction on CsSOD proteins were carried out. Exon-intron structures and codon usage bias on CsSOD genes were also examined.
The exon-intron structure analysis revealed that different CsSOD genes contained several introns. On the basis of the prediction of the CsSOD regulatory miRNAs, a 5 'RNA modification was performed by ligase (RLM) -RACE and it was validated that csn-miR398a-3p-1 cleaves CsCSD4 directly. By predicting cis-acting elements, the expression patterns of 10 CsSOD genes and their regulatory miRNAs were detected under cold, drought, exogenous methyl jasmonate (MeJA) and gibberellin (GA3) treatments. The results showed that most of the CsSOD, except CsFSD2, were induced under cold stress and CsCSD can perform main functions under drought stress; Exogenous GA3 and MeJA could also stimulate / inhibit different CsSODs at different stages. Furthermore, we found that csn-miR398a-3p-1 negatively regulated the expression of CsCSD4 may be a crucial regulatory mechanism under cold stress. This study provides some basis for studies on stress resistance in tea plants, and even provides information to understand classification, evolution, various functions, and factors that influence the expression patterns of CsSOD genes.