Poster: Intercellular Signaling

Abs # 809: Extracellular ATP signaling and apyrase expression changes in the wound response in Arabidopsis thaliana

Presenter:	Song, Charlotte , charlotte_song@mail.utexas.edu
Authors	Song, Charlotte  (A)   Roux, Stanley  (A)
Affiliations:	(A): University of Texas at Austin

Extracellular ATP is a known signal that has been studied in animals. Apyrases hydrolyze ATP, thereby quenching the signal, and two apyrases have been described in Arabidopsis: Atapy1 and Atapy2. Upon wounding, ATP exudes from the wound site in significant amounts in Arabidopsis. After wounding, apyrases are differentially expressed. Atapy1 expression increases from the control within 5 minutes of wounding. Atapy2 transcript decreases within 5 minutes after wounding. These data indicate that the two different apyrases may have different functions in the wounded plant. Different levels of ATP and ADP were infiltrated into leaves. The expression levels of two genes known to play a role in the wound response were examined: LOX2 and ACC synthase. LOX2 is an important enzyme in the production of jasmonic acid, and ACC synthase is a key enzyme in the production of ethylene. 5 mM ATP induces a significant increase in the transcript level of LOX2 above 1 mM ATP and the control. As the concentration of ATP increases up to 50 mM ATP, the level of transcript decreases. The transcript level of ACC synthase is the same as control at 1 mM ATP. There is an increase in transcript level at 5 mM ATP, but less intense compared to LOX2 expression. The transcript level of ACC synthase decreases as the concentration of ATP increases up to 50 mM ATP, similar to LOX2 expression. Reactive oxygen species are generated in Arabidopsis plants upon wounding. Superoxide was produced when the leaves were infiltrated with various concentrations of ATP. A strong response was seen with ATP levels as low as 5 mM, suggesting an additional link between exogenous ATP and wound responses. Supported by NSF 1BN0080363