title: An Arabidopsis mutant impaired in intracellular calcium elevation is sensitive to biotic and abiotic stress.
abstract: BACKGROUND
  Ca2+, a versatile intracellular second messenger in various signaling pathways, initiates many responses involved in growth, defense and tolerance to biotic and abiotic stress. Endogenous and exogenous signals induce cytoplasmic Ca2+ ([Ca2+]cyt) elevation, which are responsible for the appropriate downstream responses.
  
  
  RESULTS
  Here we report on an ethyl-methane sulfonate-mediated Arabidopsis mutant that fails to induce [Ca2+]cyt elevation in response to exudate preparations from the pathogenic mibrobes Alternaria brassicae, Rhizoctonia solani, Phytophthora parasitica var. nicotianae and Agrobacterium tumefaciens. The cytoplasmic Ca2+elevation mutant1 (cycam1) is susceptible to infections by A. brassicae, its toxin preparation and sensitive to abiotic stress such as drought and salt. It accumulates high levels of reactive oxygen species and contains elevated salicylic acid, abscisic acid and bioactive jasmonic acid iso-leucine levels. Reactive oxygen species- and phytohormone-related genes are higher in A. brassicae-treated wild-type and mutant seedlings. Depending on the analysed response, the elevated levels of defense-related compounds are either caused by the cycam mutation and are promoted by the pathogen, or they are mainly due to the pathogen infection or application of pathogen-associated molecular patterns. Furthermore, cycam1 shows altered responses to abscisic acid treatments: the hormone inhibits germination and growth of the mutant.
  
  
  CONCLUSIONS
  We isolated an Arabidopsis mutant which fails to induce [Ca2+]cyt elevation in response to exudate preparations from various microbes. The higher susceptibility of the mutant to pathogen infections correlates with the higher accumulation of defense-related compounds, such as phytohormones, reactive oxygen-species, defense-related mRNA levels and secondary metabolites. Therefore, CYCAM1 couples [Ca2+]cyt elevation to biotic, abiotic and oxidative stress responses.
authors.forename: Joy
authors.initials: J
authors.lastname: Michal Johnson
authors.forename: Michael
authors.initials: M
authors.lastname: Reichelt
authors.forename: Jyothilakshmi
authors.initials: J
authors.lastname: Vadassery
authors.forename: Jonathan
authors.initials: J
authors.lastname: Gershenzon
authors.affiliation: Institute of General Botany and Plant Physiology, Friedrich-Schiller-University Jena, Dornburger Str, 159, 07743 Jena, Germany. b7oera@uni-jena.de.
authors.forename: Ralf
authors.initials: R
authors.lastname: Oelmüller
mesh_terms: D000040:Abscisic Acid / Q000494:pharmacology; D000528:Alternaria / Q000737:chemistry / Q000187:drug effects; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics; D002118:Calcium / Q000378:metabolism*; D002473:Cell Wall / Q000187:drug effects / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D055864:Droughts; D017343:Genes, Plant; D018525:Germination / Q000187:drug effects; D005961:Glucosinolates / Q000378:metabolism; D007211:Indoles / Q000378:metabolism; D042541:Intracellular Space / Q000187:drug effects / Q000378:metabolism*; D008954:Models, Biological; D009154:Mutation / Q000235:genetics*; D025282:Mycelium / Q000737:chemistry / Q000187:drug effects; D010935:Plant Diseases / Q000382:microbiology; D010937:Plant Growth Regulators / Q000378:metabolism; D018517:Plant Roots / Q000378:metabolism / Q000382:microbiology; D017382:Reactive Oxygen Species / Q000378:metabolism; D036226:Seedlings / Q000187:drug effects / Q000254:growth & development / Q000502:physiology; D012965:Sodium Chloride / Q000494:pharmacology; D013172:Spores, Fungal / Q000737:chemistry; D013312:Stress, Physiological / Q000187:drug effects; D013844:Thiazoles / Q000378:metabolism; D000094162:Phytoalexins
chemical_list: D000040:Abscisic Acid; D029681:Arabidopsis Proteins; D002118:Calcium; D005961:Glucosinolates; D007211:Indoles; D010937:Plant Growth Regulators; D017382:Reactive Oxygen Species; D012965:Sodium Chloride; D013844:Thiazoles; C102405:camalexin; D000094162:Phytoalexins