title: Identification, expression and interaction analyses of calcium-dependent protein kinase (CPK) genes in canola (Brassica napus L.).
abstract: BACKGROUND
  Canola (Brassica napus L.) is one of the most important oil-producing crops in China and worldwide. The yield and quality of canola is frequently threatened by environmental stresses including drought, cold and high salinity. Calcium is a well-known ubiquitous intracellular secondary messenger in plants. Calcium-dependent protein kinases (CPKs) are Ser/Thr protein kinases found only in plants and some protozoans. CPKs are Ca2+ sensors that have both Ca2+ sensing function and kinase activity within a single protein and play crucial roles in plant development and responses to various environmental stresses.
  
  
  RESULTS
  In this study, we mined the available expressed sequence tags (ESTs) of B. napus and identified a total of 25 CPK genes, among which cDNA sequences of 23 genes were successfully cloned from a double haploid cultivar of canola. Phylogenetic analysis demonstrated that they could be clustered into four subgroups. The subcellular localization of five selected BnaCPKs was determined using green fluorescence protein (GFP) as the reporter. Furthermore, the expression levels of 21 BnaCPK genes in response to salt, drought, cold, heat, abscisic acid (ABA), low potassium (LK) and oxidative stress were studied by quantitative RT-PCR and were found to respond to multiple stimuli, suggesting that canola CPKs may be convergence points of different signaling pathways. We also identified and cloned five and eight Clade A basic leucine zipper (bZIP) and protein phosphatase type 2C (PP2C) genes from canola and, using yeast two-hybrid and bimolecular fluorescence complementation (BiFC), determined the interaction between individual BnaCPKs and BnabZIPs or BnaPP2Cs (Clade A). We identified novel, interesting interaction partners for some of the BnaCPK proteins.
  
  
  CONCLUSIONS
  We present the sequences and characterization of CPK gene family members in canola for the first time. This work provides a foundation for further crop improvement and improved understanding of signal transduction in plants.
authors.forename: Hanfeng
authors.initials: H
authors.lastname: Zhang
authors.forename: Wu-Zhen
authors.initials: WZ
authors.lastname: Liu
authors.forename: Yupeng
authors.initials: Y
authors.lastname: Zhang
authors.forename: Min
authors.initials: M
authors.lastname: Deng
authors.forename: Fangfang
authors.initials: F
authors.lastname: Niu
authors.affiliation: State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A & F University, Yangling, Shaanxi 712100, China. yangwl@nwafu.edu.cn.
authors.forename: Bo
authors.initials: B
authors.lastname: Yang
authors.forename: Xiaoling
authors.initials: X
authors.lastname: Wang
authors.forename: Boya
authors.initials: B
authors.lastname: Wang
authors.forename: Wanwan
authors.initials: W
authors.lastname: Liang
authors.forename: Michael K
authors.initials: MK
authors.lastname: Deyholos
authors.forename: Yuan-Qing
authors.initials: YQ
authors.lastname: Jiang
mesh_terms: D000040:Abscisic Acid / Q000494:pharmacology; D050976:Basic-Leucine Zipper Transcription Factors / Q000235:genetics / Q000378:metabolism; D029688:Brassica napus / Q000201:enzymology* / Q000235:genetics* / Q000378:metabolism; D055864:Droughts; D020224:Expressed Sequence Tags; D015971:Gene Expression Regulation, Enzymologic; D018745:Genome, Plant; D008969:Molecular Sequence Data; D018384:Oxidative Stress; D010749:Phosphoprotein Phosphatases / Q000235:genetics / Q000378:metabolism; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D011494:Protein Kinases / Q000235:genetics* / Q000378:metabolism; D000071636:Protein Phosphatase 2C; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012492:Salts / Q000494:pharmacology; D013696:Temperature; D059467:Transcriptome / Q000187:drug effects; D020798:Two-Hybrid System Techniques; D017871:Calcium-Calmodulin-Dependent Protein Kinases
chemical_list: D000040:Abscisic Acid; D050976:Basic-Leucine Zipper Transcription Factors; D010749:Phosphoprotein Phosphatases; D010940:Plant Proteins; D011494:Protein Kinases; D000071636:Protein Phosphatase 2C; D012492:Salts; D017871:Calcium-Calmodulin-Dependent Protein Kinases