The involvements of calcium-dependent protein kinases and catechins in tea plant [Camellia sinensis (L.) O. Kuntze] cold responses.

Temperature is one of the most important environmental factors limiting tea plant growth and tea production. Previously we reported that both Ca2+ and ROS signals play important roles in tea plant cold acclimation. Here, we identified 26 CsCPK transcripts, analyzed their phylogenetic and sequence characters, and detected their transcriptions to monitor Ca2+ signaling status. Tissue-specific expression profiles indicated that most CsCPK genes were constitutively expressed in tested tissues, suggesting their possible roles in development. Cold along with calcium inhibitor assays suggested that CsCPKs are important cold regulators and CsCPK30/5/4/9 maybe the key members. Moreover, LaCl3 or EGTA pre-treatment could result in impaired Ca2+ signaling and compromised cold-responding network, but higher catechins accumulation revealed their potential positive roles in cold responses. Those findings indicated that catechins and other secondary metabolites in tea plant may form an alternative cold-responding network that closely correlated with Ca2+ signaling status.