title: Apyrase suppression raises extracellular ATP levels and induces gene expression and cell wall changes characteristic of stress responses.
abstract: Plant cells release ATP into their extracellular matrix as they grow, and extracellular ATP (eATP) can modulate the rate of cell growth in diverse tissues. Two closely related apyrases (APYs) in Arabidopsis (Arabidopsis thaliana), APY1 and APY2, function, in part, to control the concentration of eATP. The expression of APY1/APY2 can be inhibited by RNA interference, and this suppression leads to an increase in the concentration of eATP in the extracellular medium and severely reduces growth. To clarify how the suppression of APY1 and APY2 is linked to growth inhibition, the gene expression changes that occur in seedlings when apyrase expression is suppressed were assayed by microarray and quantitative real-time-PCR analyses. The most significant gene expression changes induced by APY suppression were in genes involved in biotic stress responses, which include those genes regulating wall composition and extensibility. These expression changes predicted specific chemical changes in the walls of mutant seedlings, and two of these changes, wall lignification and decreased methyl ester bonds, were verified by direct analyses. Taken together, the results are consistent with the hypothesis that APY1, APY2, and eATP play important roles in the signaling steps that link biotic stresses to plant defense responses and growth changes.
authors.affiliation: Departments of Molecular Biosciences and.
authors.forename: Min Hui
authors.initials: MH
authors.lastname: Lim
authors.forename: Jian
authors.initials: J
authors.lastname: Wu
authors.forename: Jianchao
authors.initials: J
authors.lastname: Yao
authors.forename: Ignacio F
authors.initials: IF
authors.lastname: Gallardo
authors.forename: Jason W
authors.initials: JW
authors.lastname: Dugger
authors.forename: Lauren J
authors.initials: LJ
authors.lastname: Webb
authors.forename: James
authors.initials: J
authors.lastname: Huang
authors.forename: Mari L
authors.initials: ML
authors.lastname: Salmi
authors.forename: Jawon
authors.initials: J
authors.lastname: Song
authors.forename: Greg
authors.initials: G
authors.lastname: Clark
authors.forename: Stanley J
authors.initials: SJ
authors.lastname: Roux
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D001081:Apyrase / Q000235:genetics / Q000378:metabolism*; D017360:Arabidopsis / Q000166:cytology / Q000201:enzymology* / Q000502:physiology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002473:Cell Wall / Q000201:enzymology / Q000378:metabolism*; D015536:Down-Regulation / Q000235:genetics; D005109:Extracellular Matrix / Q000235:genetics / Q000378:metabolism; D005110:Extracellular Space / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D063990:Gene Ontology; D017343:Genes, Plant; D006861:Hydrogen Peroxide / Q000378:metabolism; D008031:Lignin / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D020411:Oligonucleotide Array Sequence Analysis; D009195:Peroxidase / Q000378:metabolism; D018517:Plant Roots / Q000378:metabolism; D034622:RNA Interference; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D015203:Reproducibility of Results; D013312:Stress, Physiological / Q000235:genetics; D015854:Up-Regulation / Q000235:genetics
chemical_list: D029681:Arabidopsis Proteins; D012333:RNA, Messenger; D000255:Adenosine Triphosphate; D008031:Lignin; D006861:Hydrogen Peroxide; D009195:Peroxidase; C522733:APY1 protein, Arabidopsis; C522734:APY2 protein, Arabidopsis; D001081:Apyrase