EXPRESSION OF PROTEIN PHOSPHATASE 2A AND SUGAR SIGNALING IN WHEAT LEAVES

MARTÍNEZ-NOËL G; TOGNETTI J; PONTIS H

Cordoba, Argentina

Congreso; SAIB; 2002

SAIB

In addition to playing a central role in metabolism, soluble sugars such as Glu and Suc help regulate many developmental and physiological processes in plants. Sugars have important hormone-like fumtions as primary messengers in signal transduction but the molecular mechanisms by which sugars act remain largely unknown. Protein kinases, protein phosphatases (PP), Ca and calmodulin have been implicated in sugar-mediated signaling. We have previously demostrated that okadaic acid, a Ser/Thr inhibitor blocks the induction of the sucrose:fructan 6-fructosyltransferase in wheat leaves. Taken together these results we started to study the PP2A activity and their role in sugar signaling. We could measure PP2A activity in wheat leaves treated with water (W, control) or with sucrose 0.5M (Suc). At short term treatment (3 hs) the levels of activities were nearly the same for both treatments but at 6 hs or longer treatments with Suc the PP2A activity decreased. Also, we did a first step of purification with ion exchange chromatography on DEAE Sephacell with wheat leaves treated with W or Suc. We found that the perfil patterns were similar for both treatments and the PP2A activity was lower with the Suc treatment. These evidences suggest that the PP2A activity is necessary for the sugar signaling and the activity existing is enough Further work to clarified the role of the PP2A in sugar signaling will be necessary. Supported by ANPCyT and FIBA.