Genome-Wide Identification and Characterization of the Superoxide Dismutase (SOD) Gene Family in Pakchoi and the Role of the BchFSD2 Gene in the Salt Stress Toleran

Superoxide dismutase (SOD) is an important antioxidant metalloenzyme present in plants that plays a vital role in plant growth and development, but studies on the SOD gene family in Pakchoi are lacking. In this study, we identified 13 SOD genes from pakchoi, including three MnSODs, five Cu/ZnSODs, and five FeSODs. Through structural analysis, the gene structures and motif patterns in the three subfamilies showed a high degree of conservation. From an evolutionary point of view, gene duplication is an important pathway driving the evolutionary development of the SOD gene family. In addition, by analyzing the structure and function of BchSOD proteins, most of the genes were shown to be involved in different developmental stages of pakchoi, and their expression was shown to be regulated by external conditions such as light, phytohormones, and abiotic stress. qPCR results revealed that BchSODs were expressed in different parts of pakchoi, and most of the genes were expressed in response to abiotic stresses (salt and drought) and hormones (GA and MeJA). In addition, the BchFSD2 gene was studied in depth, and subcellular localization confirmed that the BchFSD2 gene was expressed in plant chloroplasts. Overexpression of BchFSD2 promoted salt tolerance, limited superoxide anion and MDA production, and increased antioxidant enzyme activities in Arabidopsis. In summary, the BchSOD gene family was comprehensively analyzed in this study to provide new insights for a better understanding of BchSOD function and to improve salt tolerance in pakchoi.