The differences between two tea varieties in their response to natural cold conditions

In this study, two tea varieties (Camellia sinensis cv. CsCr02 and CsCr03) were studied under natural cold conditions to investigate the differences of thylakoid membrane structure, fatty acid desaturase (FAD) genes, and fatty acid (FA) composition in response to low temperatures. Quantitative real-time polymerase chain reaction assay confirmed that the expression of CsFAD8 in leaves of the two tea varieties was much higher than that of CsFAD7. The expression of both genes in CsCr03 was higher than in CsCr02. Electron microscopy showed that the damage to the thylakoid membrane in CsCr03 was less severe than in CsCr02 during the decrease of natural temperature. Changes in thylakoid membrane integrity coincided with the gradual decline in chlorophyll concentration and chlorosis of the tea leaves. With the decrease of natural temperature, a decline in the trienoic FA species (16:3 and 18:3) and an increase in the dienoic species (18:2) were observed in the two varieties. These results indicate that CsCr03 has higher cold adaptability compared to CsCr02.