Abstract:

To study the changes of antioxidant enzyme activity and the expression of key genes in Camellia reticulata during drought stress and rehydration process, this paper used semi-annual Camellia reticulata seedlings to determine the peroxidase (POD) and superoxide dismutase (SOD) activities of Camellia reticulata leaves under drought stress using polyethylene glycol (PEG-6000), and transcriptome sequencing was performed on leaves of the control group and the severely drought stress group. The results showed that during the stress period, the SOD activity of each treatment group showed a continuous upward trend, and the POD activity firstly increased and then decreased under severe drought stress. During the rehydration period, the activities of POD and SOD showed a downward trend, except for the mild drought stress group, the POD and SOD activities of the other two groups could not recover to the level before stress. Through the analysis of differential expression of key genes, it was found that the expression of 33 antioxidant enzyme-related genes was very significantly correlated with antioxidant enzyme activity (P<0.01) and 19 antioxidant enzyme-related genes showed significant correlation (P<0.05) during severe drought stress and rehydration. POD-related genes were enriched in the phenylpropane biosynthesis pathway, and SOD-related genes were mainly enriched in the peroxisome pathway, all of which were down-regulated. The relevant expression levels changed significantly after the start of stress, indicating that antioxidant enzyme-related genes participated in the regulation of drought stress and rehydration, and actively responded to drought stress.

Key words: Camellia reticulata, drought stress, rehydration, antioxidant enzymes, gene expression