Extracellular ATP signaling in plants

Abstract

Extracellular adenosine-5′-triphosphate (ATP) induces a number of cellular responses in plants and animals. Some of the molecular components for purinergic signaling in animal cells appear to be lacking in plant cells, although some cellular responses are similar in both systems [e.g. increased levels of cytosolic free calcium, nitric oxide (NO), and reactive oxygen species (ROS)]. The purpose of this review is to compare and contrast purinergic signaling mechanisms in animal and plant cells. This comparison will aid our overall understanding of plant physiology and also provide details of the general fundamentals of extracellular ATP signaling in eukaryotes.

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

“…In common with ATP, it is likely that ADP is released on wounding and could perhaps also be released with ATP by exocytosis or the activity of ATP-binding cassette transporters (Thomas et al, 2000;Kim et al, 2006;Tanaka et al, 2010a). Extracellular ATP hotspots have been found in elongating root cells (Kim et al, 2006) and ADP may also be released there.…”

“…Moreover, there is a dose-dependent effect of extracellular ADP on Arabidopsis root hair elongation (Clark et al, 2010b) further implicating extracellular ADP in growth regulation. Plant extracellular apyrases can hydrolyze ADP to regulate its extracellular levels and so terminate any signal it could invoke (Komoszyń ski, 1996;Steinebrunner et al, 2003;Riewe et al, 2008aRiewe et al, , 2008bTanaka et al, 2010aTanaka et al, , 2010b.…”

“…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).…”

Cellular function and molecular structure of ecto-nucleotidases

“…The apparent lack of P2X receptors in these organisms [187] further supports the notion that expression of ecto-NTPDases is a hallmark of purinergic signaling. In contrast, members of the protein family relating to the intracellular forms are present throughout the animal kingdom and also in plants and fungi [37,188]. Surprisingly, members of the ectoNTPDase family have been identified at the surface of several pathogenic protozoans and in no more but a few bacteria, including Legionella pneumophila, the causative agent of Legionaires' disease [37,189].…”

“…In plants, NTPDases are thought to be involved in growth and symbiosis between plants and microbes. Even though extracellular ATP exhibits specific physiological effects, purinergic receptors have not been identified in plants [188]. The family of proteins related to NTPDase1 (CD39) and yeast GDPase (GAD1) are also referred to as GAD1_CD39 superfamily [37].…”