Physiological and biochemical changes and gene expression related to antioxidant enzyme activity of two ploidy Camellia reticulata species under low temperature stress

Abstract [Objective] Camellia reticulata is the first of the eight famous flowers in Yunnan, but it is poor in cold tolerance. This paper discusses the cold tolerance of two ploidy C. reticulata from the physiological and molecular levels, which can provide references for the mining of cold tolerance genes and molecular breeding of C. reticulata. [Methods] Using tetraploid (4X) and hexaploid (6X) annual seedlings of wild C. reticulata as materials, physiological indexes and transcriptomic sequencing of leaves of C. reticulata were analyzed after low temperature (-4 ℃) treatment. [Results] Based on the observation of leaf phenotype, from the stress period to the rewarming period, the damage degree of the hexaploid leaves was relatively smaller, and the cold resistance performance of the hexaploid leaves was better than that of the tetraploid leaves. According to the results of physiological indexes, except for MDA and GSH, the accumulation of other physiological indexes of the hexaploid was greater than that of the tetraploid. Correlation analysis of antioxidase activity and the differential genes showed that 5 and 7, 7 and 17 genes were significantly correlated with GSH content and POD activity in tetraploid and hexaploid, respectively, and only 2 genes in hexaploid were significantly correlated with SOD activity. [Conclusion] Hexaploid is more effective than tetraploid in alleviating the damage of plants under low temperature stress. Antioxidase-related genes may be involved in the regulation of low temperature resistance by regulating their activity.