Abstract
Background: Class Ⅲ peroxidases (PODs) are widely involved in multiple physiological processes, including lignin biosynthesis and stress responses. However, there are no reports on the identification and function of POD family in Hippophae rhamnoides subsp. sinensis Rousi. Results: In this study, we identified 71 non-redundant HrPODs. Based on phylogenetic analysis, these genes were classified into 7 subgroups. Then, we analyzed the conserved domains of HrPODs proteins and found that they contain highly conserved domain. We also investigated their expression patterns in three developmental stages of sea buckthorn fruit, and the results showed that most of them were highly expressed in early stage. The GO and KEGG functional enrichment analysis showed that they widely involved in oxidative stress response and phenylpropanoid biosynthesis, respectively. According to the Pearson correlation analysis of HrPODs expression with lignin content and peroxidase activity, we further screened five HrPODs that may be involved in fruit texture quality by regulating lignin biosynthesis during fruit development. Sea buckthorn is usually distributed in arid areas with higher salt and alkaline content, and our findings showed that the different degrees of drought, salt, or alkali treatment can also affect the expression of these genes and lignin content during the germination stage. These results will help us better investigate the role of HrPODs in lignin biosynthesis to provide certain theoretical foundation in ideal berry breeding and broad spectrum stress resistance in cultivated sea buckthorn. Conclusion: In this study, the findings not only provide us with a comprehensive identification and analysis of HrPODs from a bioinformatics perspective, but also preliminary intimation that the POD family may be tightly associated with fruit texture quality and abiotic stress response. These results will help us better investigate the role of HrPODs in lingin biosynthesis, enrich the theoretical research on the formation of sea buckthorn texture quality and understand the roles of HrPODs in abiotic stress resistance in cultivated sea buckthorn.