title: Differential expression of CPKs and cytosolic Ca2+ variation in resistant and susceptible apple cultivars (Malus x domestica) in response to the pathogen Erwinia amylovora and mechanical wounding.
abstract: BACKGROUND
  Plant calcium (Ca2+) signals are involved in a wide array of intracellular signalling pathways following pathogen invasion. Ca2+-binding sensory proteins such as Ca2+-dependent protein kinases (CPKs) have been predicted to mediate signalling following Ca2+ influx after pathogen infection. However, to date this prediction has remained elusive.
  
  
  RESULTS
  We conducted a genome-wide identification of the Malus x domestica CPK (MdCPK) gene family and identified 30 CPK genes. Comparative phylogenetic analysis of Malus CPKs with CPKs of Arabidopsis thaliana (AtCPKs), Oryza sativa (OsCPKs), Populous trichocarpa (PtCPKs) and Zea mays (ZmCPKs) revealed four different groups. From the phylogenetic tree, we found that MdCPKs are closely related to AtCPKs and PtCPKs rather than OsCPKs and ZmCPKs, indicating their dicot-specific origin. Furthermore, comparative quantitative real time PCR and intracellular cytosolic calcium ([Ca2+]cyt) analysis were carried out on fire blight resistant and susceptible M. x domestica apple cultivars following infection with a pathogen (Erwinia amylovora) and/or mechanical damage. Calcium analysis showed an increased [Ca2+]cyt over time in resistant cultivars as compared to susceptible cultivars. Gene expression studies showed that 11 out of the 30 MdCPKs were differentially expressed following pathogen infection.
  
  
  CONCLUSIONS
  We studied the genome-wide analysis of MdCPK gene family in Malus x domestica and analyzed their differential gene expression along with cytosolic calcium variation upon pathogen infection. There was a striking difference in MdCPKs gene expressions and [Ca2+]cyt variations between resistant and susceptible M. x domestica cultivars in response to E. amylovora and mechanical wounding. Our genomic and bioinformatic analysis provided an important insight about the role of MdCPKs in modulating defence responses in susceptible and resistant apple cultivars. It also provided further information on early signalling and downstream signalling cascades in response to pathogenic and mechanical stress.
authors.affiliation: Research and Innovation Centre Genomics and Biology of Fruit Crop Department, Fondazione Edmund Mach (FEM), Istituto Agrario San Michele (IASMA), Via Mach 1, 38010, San Michele all'Adige (TN), Italy. chidananda.nagamangala@fmach.it.
authors.forename: Chidananda Nagamangala
authors.initials: CN
authors.lastname: Kanchiswamy
authors.forename: Tapan Kumar
authors.initials: TK
authors.lastname: Mohanta
authors.forename: Andrea
authors.initials: A
authors.lastname: Capuzzo
authors.forename: Andrea
authors.initials: A
authors.lastname: Occhipinti
authors.forename: Francesca
authors.initials: F
authors.lastname: Verrillo
authors.forename: Massimo E
authors.initials: ME
authors.lastname: Maffei
authors.forename: Mickael
authors.initials: M
authors.lastname: Malnoy
mesh_terms: D020013:Calcium Signaling / Q000235:genetics; D060467:Disease Resistance / Q000235:genetics*; D044084:Erwinia amylovora / Q000235:genetics / Q000472:pathogenicity*; D018506:Gene Expression Regulation, Plant; D018745:Genome, Plant; D027845:Malus / Q000235:genetics / Q000382:microbiology; D010802:Phylogeny; D010935:Plant Diseases / Q000235:genetics* / Q000382:microbiology; D011494:Protein Kinases / Q000096:biosynthesis* / Q000145:classification / Q000235:genetics; D013314:Stress, Mechanical
chemical_list: D011494:Protein Kinases