Proceedings of the XLVII Italian Society of Agricultural Genetics - SIGA Annual Congress

Verona, Italy - 24/27 September, 2003

ISBN 88-900622-4-X

Poster Abstract - 5.03

MODULATION OF PLASMA MEMBRANE H⁺-ATPASE ACTIVITY IN TOMATO PLANTS INFECTED WITH PSEUDOMONAS SYRINGAE PATHOVAR TOMATO

L. CAMONI, A. GARUFI, P. ADUCCI

Dipartimento di Biologia, Università di Roma “Tor Vergata”, via della Ricerca Scientifica, 00133 Roma

H⁺-ATPase, Pseudomonas syringae pv. tomato, 14-3-3 proteins, Lycopersicon esculentum, plant-pathogen interactions.

The plasma membrane H⁺-ATPase is the major ion pump in the plasma membrane of higher plants (Palmgren, 1998). This enzyme generates an electrochemical gradient which provides the driving force for a number of key physiological processes such as stomata opening, phloem loading and root ion uptake.

The important functions of the plasma membrane H+-ATPase suggest that the activity of the enzyme is tightly controlled. Recently, it has been demonstrated that the proton pump is activated by phosphorylation dependent binding of 14-3-3 proteins to the C-terminal domain of the enzyme (Aducci et al, 2002).

Different clues indicate that the H+-ATPase is also involved in the mechanisms of defence during pathogen infection. In fact,the proton pump activator fusicoccin (FC) induces the expression of pathogenesis related (PR) genes and the accumulation of salicylic acid in tomato plants (Schaller and Oecking, 1999; Roberts and Bowles; 1999); furthermore, it has been demonstrated that proton extrusion is an essential signalling component in the HR of epidermal single cells in the barley-powdery mildew interaction (Zhou et al., 2000).

Given the potential role of the H⁺-ATPase in plant-pathogen interactions, we tested the H⁺-ATPase activity in different tomato (Lycopersicon esculentum ) ecotypes (San Marzano, Corbarino, Sorrento, Vesuviano) infected with Pseudomonas syringae pv. tomato.

Interestingly, the H⁺-ATPase from infected plants is purified in activated form. Western blotting experiments demonstrated that higher levels of 14-3-3 proteins are associated to the plasma membrane fraction of infected plants; furthermore, the H⁺-ATPase purified from these plants displays an higher affinity for 14-3-3 protein in overlay assay.

The significance of H⁺-ATPase activation in the interaction tomato-Pseudomonas syringae pv. tomato is currently under investigation.

REFERENCES

Palmgren M.G. (1998). Proton gradients and plant growth: role of the plasma membrane H⁺-ATPase. Advances in Botanical Research 28, 1-70.

Aducci P., Camoni L., Marra M., Visconti S. (2002) From cytosol to organelles: 14-3-3 proteins as multifunctional regulators of plant cell. IUBMB Life 53, 49-55.

Scaller, A., Oecking, C. (1999) Modulation of plasma membrane H⁺-ATPase activity differentially activates wound and pathogen defense responses in tomato plants. Plant Cell.11:263-72.

Roberts MR., Bowles DJ. (1999) Fusicoccin, 14-3-3 proteins, and defense responses in tomato plants. Plant Physiology. 119, 1243-50.

Zhou F, Andersen CH, Burhenne K, Fischer PH, Collinge DB, Thordal-Christensen H. (2000) Proton extrusion is an essential signalling component in the HR of epidermal single cells in the barley-powdery mildew interaction. Plant Journal 23, 245-54.