Apyrases (Nucleoside Triphosphate-Diphosphohydrolases) Play a Key Role in Growth Control in Arabidopsis

Abstract

Expression of two Arabidopsis (Arabidopsis thaliana) apyrase (nucleoside triphosphate-diphosphohydrolase) genes with high similarity, APY1 and APY2, was analyzed during seedling development and under different light treatments using b-glucuronidase fusion constructs with the promoters of both genes. As evaluated by b-glucuronidase staining and independently confirmed by other methods, the highest expression of both apyrases was in rapidly growing tissues and/or tissues that accumulate high auxin levels. Red-light treatment of etiolated seedlings suppressed the protein and message level of both apyrases at least as rapidly as it inhibited hypocotyl growth. Adult apy1 and apy2 single mutants had near-normal growth, but apy1apy2 doubleknockout plants were dwarf, due primarily to reduced cell elongation. Pollen tubes and etiolated hypocotyls overexpressing an apyrase had faster growth rates than wild-type plants. Growing pollen tubes released ATP into the growth medium and suppression of apyrase activity by antiapyrase antibodies or by inhibitors simultaneously increased medium ATP levels and inhibited pollen tube growth. These results imply that APY1 and APY2, like their homologs in animals, act to reduce the concentration of extracellular nucleotides, and that this function is important for the regulation of growth in Arabidopsis.

Purification and Biochemical Characterization of a Novel Ecto-Apyrase, MP67, from Mimosa pudica

“…In other plants, roles of apyrases in cell growth were reported (Riewe et al, 2008;Clark et al, 2010). In Arabidopsis (Arabidopsis thaliana), two ecto-apyrases, AtAPY1 and AtAPY2, play critical roles in controlling the extracellular ATP concentration, thereby contributing to growth (Wu et al, 2007). Like all members of the E-type ATPase family, apyrases share five highly conserved sequences called apyrase conserved regions (ACRs; Handa and Guidotti, 1996;Vasconcelos et al, 1996) that might be important for nucleotide hydrolysis.…”

Receptor-Like Activity Evoked by Extracellular ADP in Arabidopsis Root Epidermal Plasma Membrane

“…Manipulation of ecto-apyrase levels results in abnormal growth in Arabidopsis (Arabidopsis thaliana), cotton (Gossypium hirsutum), and potato (Solanum tuberosum; Wu et al, 2007;Riewe et al, 2008a;Clark et al, 2010aClark et al, , 2010b while nodulation by Bradyrhizobium japonicum is impaired in ecto-apyrase-deficient soybean (Glycine max; Govindarajulu et al, 2009). Current models suggest that poise of the cell's state between death, stress adaptation, and growth involves signaling governed by the level of extracellular ATP (Chivasa et al, 2005Roux and Steinebrunner, 2007;Wu et al, 2007;Wu and Wu, 2008;Kim et al, 2009;Clark et al, 2010aClark et al, , 2010bTerrile et al, 2010;Tonó n et al, 2010).…”

“…Extracellular purine nucleotides have been shown to be involved in the regulation of plant cell viability, membrane permeability, immunity, symbiosis, stress responses, and growth (Lew and Dearnaley, 2000;Tang et al, 2003;Chivasa et al, 2005Chivasa et al, , 2009Kim et al, 2006Kim et al, , 2009Roux and Steinebrunner, 2007;Wu et al, 2007;Riewe et al, 2008a;Wu and Wu, 2008;Yi et al, 2008;Demidchik et al, 2009;Govindarajulu et al, 2009;Kim et al, 2009;Clark et al, 2010aClark et al, , 2010bTanaka et al, 2010aTanaka et al, , 2010bTerrile et al, 2010;Tonó n et al, 2010). Purine nucleotide release from plant cells may occur through wounding, exocytosis, or through the activity of plasma membrane (PM) ATP-binding cassette transporters (Thomas et al, 2000;Kim et al, 2006).…”

“…Growth points are hotspots of extracellular ATP (Kim et al, 2006) while touch-stimulated ATP release is mediated by heterotrimeric G-protein activity (Weerasinghe et al, 2009). Levels of extracellular ATP and ADP can be regulated by the concerted action of ecto-apyrases, phosphatases, and adenosine nucleosidases with retrieval of adenine (the ultimate hydrolytic product) by PM purine permeases (Komoszyń ski, 1996;Steinebrunner et al, 2003;Wu et al, 2007;Riewe et al, 2008aRiewe et al, , 2008bGovindarajulu et al, 2009;Clark et al, 2010b;Liang et al, 2010). Manipulation of ecto-apyrase levels results in abnormal growth in Arabidopsis (Arabidopsis thaliana), cotton (Gossypium hirsutum), and potato (Solanum tuberosum; Wu et al, 2007;Riewe et al, 2008a;Clark et al, 2010aClark et al, , 2010b while nodulation by Bradyrhizobium japonicum is impaired in ecto-apyrase-deficient soybean (Glycine max; Govindarajulu et al, 2009).…”

“…Levels of extracellular ATP and ADP can be regulated by the concerted action of ecto-apyrases, phosphatases, and adenosine nucleosidases with retrieval of adenine (the ultimate hydrolytic product) by PM purine permeases (Komoszyń ski, 1996;Steinebrunner et al, 2003;Wu et al, 2007;Riewe et al, 2008aRiewe et al, , 2008bGovindarajulu et al, 2009;Clark et al, 2010b;Liang et al, 2010). Manipulation of ecto-apyrase levels results in abnormal growth in Arabidopsis (Arabidopsis thaliana), cotton (Gossypium hirsutum), and potato (Solanum tuberosum; Wu et al, 2007;Riewe et al, 2008a;Clark et al, 2010aClark et al, , 2010b while nodulation by Bradyrhizobium japonicum is impaired in ecto-apyrase-deficient soybean (Glycine max; Govindarajulu et al, 2009). Current models suggest that poise of the cell's state between death, stress adaptation, and growth involves signaling governed by the level of extracellular ATP (Chivasa et al, 2005Roux and Steinebrunner, 2007;Wu et al, 2007;Wu and Wu, 2008;Kim et al, 2009;Clark et al, 2010aClark et al, , 2010bTerrile et al, 2010;Tonó n et al, 2010).…”