关键词: 茶树, CDPK基因, 亚细胞定位, 非生物胁迫, 表达分析

Abstract: Calcium-dependent protein kinases (CDPKs or CPKs) are important calcium sensors in higher plants, which are extensively involved in plant development and stress responding. In this study, one sequence that contained a complete ORF of 1 611 bp encoding a 568 amino acids protein was cloned from Camellia sinensis cv. Longjing 43. Sequence alignments revealed that this protein was a typical plant CDPK possesses N-terminus myristoylation site and protein kinases domain and showed the highest similarity with Arabidopsis AtCDPK17. Thus, the gene was defined as CsCDPK17 base on further phylogenetic analysis (Genbank accession No. MK238482). Basic protein character analysis shows that CsCDPK17 was a hydrophilic membrane-binding protein with molecularweight of 59.9 kD and PI of 5.43. Further subcellular localization assay using transient CsCDPK17-GFP expression in rice protoplasts and tobacco leaves proved that CsCDPK17 was localized in plasma membrane and nucleus. A series of gene transcription, light and hormone (such as ABA, SA, MeJA, etc) responding related cis-elements were detected in CsCDPK17 2 000 bp promoter regions. Tissue-specific expression analysis found that high expressions of CsCDPK17 were in the mature leaves and seeds, while the lowest transcription in roots. The transcription of CsCDPK17 was increased during cold acclimation and decreased during de-acclimation procedures in four cultivars with different cold resistance abilities. Moreover, stress induced expression indicated that CsCDPK17 could be induced by cold, drought and osmotic stresses with the highest induction levels of 5.1, 2.3 and 2.4 folds, respectively. Overall, our results suggest that the newly cloned CsCDPK17 might be involve in the regulation of both development and abiotic stress responses (such as cold, drought and osmotic stress) in tea plants.

Key words: tea plant, CDPK gene, subcellular localization, abiotic stress, expression analysis