Tea plant (Camellia sinensis) is a temperate woody plant, whose leaves are consumed as a beverage around the world, and is susceptible to low temperature. It’s growth and geographical distribution are regulated by temperature. Therefore, the study of cold response mechanism of tea plant is of great significance for breeding high resistance and quality tea varieties.

Since the 12th five-year plan, under the supports of multiple projects including Natural Science Foundation of China, a series of important progresses have been made in the mechanisms of tea plant respond to cold stress at the molecular levels by the Innovation Team of Tea Plant Genetics and Breeding from Tea Research Institute (TRI). They firstly employed RNA-Seq and digital gene expression technologies to the study of genome-wide expression profiles and identified 1,770 differentially expressed transcripts during cold acclimation (CA) in tea plants; in addition, pathway analysis indicated that the “carbohydrate metabolism pathway” and the “calcium signaling pathway” might play a vital role in tea plants’ responses to cold stress. On this basis, a variety of stress-related genes such as the transcription factor of bZIPs and the genes encoding enzymes involved in the metabolism of glycine betaine and glutathione respectively, were isolated and investigated in tea plant. Moreover, they also successfully identified over 20 aquaporin (AQP) genes and explored their expression patterns under stresses. These results let us to further know the molecular mechanism of tea plant response to low temperature.

Carbohydrates, especially of soluble sugars, play an essential role in plant cold tolerance; however, the molecular regulation of tea plant in response to cold is unclear. Recently, the researchers investigated the physiological changes including sugar contents and ultrastructure alterations in tea plants during CA, indicted that the content changes of sugar (e.g. starch, and sucrose) were correlated with the cold-tolerance of tea plants. They observed that CA induced starch degradation, which was responsible for the increase of soluble sugar content contributed to tea plants tolerance to cold. Additionally, more than 59 genes involved in the sugar metabolism, transportation, and signaling pathways were isolated, and their expression profiles were also detected over the course of a consecutive two-year assay in the winter seasons from 2012 to 2014. These results provided a comprehensive insight into the effects of CA on carbohydrates indicating that sugar accumulation contributes to tea plant cold tolerance during winter season, and a simply model of sugar regulation in response to cold stimuli is proposed.