CsCBFs Gene Response To Abiotic Stress In Camellia Sinensis And Functional Identification Of CsCBF5 Overexpression In Arabidopsis

Tea plants(Camellia sinensis(L.)O.Kuntze),perennial economic wooden plants,are planted mainly on humid,semi-humid tropical,sub-tropical and temperate acid soils and sensitive to low temperature.Low temperature freezing damage often occurs in tea cultivation in China.It is of great significance to study the cold-resistant mechanism of tea plants in screening new cold-resistant varieties.CBFs(C-repeat binding transcription factor/ dehydrate responsive element binding factors,DREB)are transcription factors closely related to low temperature regulation and they are also the hub of the plant’s resistance to cold.CBFs activate the expression of the downstream COR gene by banding CRT/DRE element of promoter of downstream genes.To study and identify the function of CsCBF gene is of great significance for improving the anti-stress ability of tea plants.In this study,we cloned the complete open reading frames of 6 CsCBF genes and study its expression pattern.We transferred CsCBF5 into wild-type Arabidopsis plants and identified its function.Main results are as follow:1.6 CsCBF genes were cloned based on genome and transcriptome databases of tea plants.All of them were deposited into the NCBI Gen Bank database under the accession numbers CsCBF1(EU563238.1),CsCBF2(KC702795.1),CsCBF3(MH017428.1),CsCBF4(KF988866.1),CsCBF5(MH165878.1)and CsCBF6(MN544638.1).2.50 CBF genes from different monocotyledons and dicotyledons plant species were selected to construct phylogenetic tree and analyse for motifs.CsCBF1,CsCBF2,CsCBF3 and CsCBF5 were clustered in a group while CsCBF4 and CsCBF6 shared a distantly related.3.p GBKT7-CsCBFs expression vectors were constructed and transformed into the Y2 HGold yeast strain.Transactivation assays showed that the CsCBFs,except CsCBF1,had transcriptional activity.p K7WGF-CsCBFs expression vectors were constructed by Gateway methods.The vectors were infiltrated into tobacco(Nicotiana tabacum)leaves for Subcellular localization.DAPI staining analysis confirmed the nuclear localization of the CsCBFs.4.CsCBFs expression was differentially induced by abiotic stress: cold,heat,PEG,salinity;plant hormones: ABA,GA,Me JA and SA.In particular,the CsCBF genes were significantly induced by cold,ABA and GA treatments.5.We transferred CsCBF5 into wild-type Arabidopsis.Transgenic plants showed showed dwarf phenotypes characteristic.Transgenic plants increased cold tolerance compared with the wild-type Arabidopsis.The expression of CsCBF5 can improve plant resistance to cold stress.CsCBF5 can also significantly up-regulate the expression of ABA-dependent pathway and non-ABA-dependent pathway genes in Arabidopsis.