Tea plant β-1, 4-glucanase enhances the propagation of Camellia tachangensis F. C. Zhang by promoting graft wound healing

Abstract

As a precious tea genetic resource in China, the ancient tea plant has a strong stress resistance and contains specific biochemical components. However, the ancient tea plant resources are vulnerable to human destruction and overuse. To better protect and utilize the individual resources of these ancient tea plants, Camellia tachangensis (Camellia tachangensis F. C. Zhang) was selected as the research object in this study, and it was grafted onto the rootstock of a cultivated tea plant (Fudingdabai) for breeding. As a glycosyl hydrolase, β-1, 4-glucanase plays a role in promoting graft wound healing in plant grafting, and can effectively break the incompatibility between different species. Therefore, a gene encoding β-1, 4 glucanase was cloned from the tea plant with a total length of 1578 bp and encodes 525 amino acids, and its expression is highest in the young leaves of the tea plant, followed by the stem. A large amount of purified β-1, 4 glucanase was obtained by yeast expression. Further analysis of this protein demonstrated that it could promote the healing of the grafted wound of Camellia tachangensis, thereby improving the grafting survival rate of Camellia tachangensis. The total catechin content, catechin index and theanine content of Camellia tachangensis after grafting with β-1,4 glucanase had no significant change compared with the no-enzyme group, and these quality components were significantly increased compared with the self-grafting of Camellia tachangensis, indicating that the quality of Camellia tachangensis could be improved by grafting with Fudingdabai as rootstock, and the use of β-1,4 glucanase not only improved the survival rate of grafted plants, but had little effect on the quality of Camellia tachangensis. In summary, in this study, a gene encoding β-1,4 glucanase was cloned from tea plant, and a large amount of purified β-1,4 glucanase was obtained. The quality and survival rate of Camellia tachangensis were improved after application of β-1,4 glucanase for grafting. This work provides new insights for the propagation of ancient tea plants.