Identification and expression analysis of Jr4CLs gene family based on transcriptome and physiological data in walnut (Juglans regia)

Shoot shriveling severely threaten growth and development of deciduous trees in northern hemisphere, its essence is imbalance of water absorption and evaporation in the branches. In this study, the physiological characteristics of ‘Xiangling’ and ‘Liaohe (Liaoning No. 4)’ during the overwintering process were studied, and key overwintering periods were selected for transcriptome analysis. The results showed that plant hormone metabolism, wax metabolism and lignin metabolism were significantly enriched during the overwintering process. The expression of 4CL, a gene related to lignin metabolism, was significantly up-regulated. We used bioinformatics to analyze the 4CL family and study its expression under drought stress, and finally screened out a highly expressed gene (Jr4CL44) for subsequent functional verification. Overexpression of Jr4CL44 can effectively remove the reactive oxygen species produced by drought stress, increase lignin content and up-regulate the expression of related genes to improve the drought resistance of Arabidopsis thaliana. These results indicate that Jr4CL44 plays an important role in plant resistance to drought stress, which lays a foundation for further study on the functions in practice.