TY  - JOUR
A1  - Graus, Dorothea
A1  - Konrad, Kai R.
A1  - Bemm, Felix
A1  - Nebioglu, Meliha Görkem Patir
A1  - Lorey, Christian
A1  - Duscha, Kerstin
A1  - Güthoff, Tilman
A1  - Herrmann, Johannes
A1  - Ferjani, Ali
A1  - Cuin, Tracey Ann
A1  - Roelfsema, M. Rob G.
A1  - Schumacher, Karin
A1  - Neuhaus, H. Ekkehard
A1  - Marten, Irene
A1  - Hedrich, Rainer
T1  - High V-PPase activity is beneficial under high salt loads, but detrimental without salinity
JF  - New Phytologist
N2  - The membrane-bound proton-pumping pyrophosphatase (V-PPase), together with the V-type H+-ATPase, generates the proton motive force that drives vacuolar membrane solute transport. Transgenic plants constitutively overexpressing V-PPases were shown to have improved salinity tolerance, but the relative impact of increasing PPi hydrolysis and proton-pumping functions has yet to be dissected.

For a better understanding of the molecular processes underlying V-PPase-dependent salt tolerance, we transiently overexpressed the pyrophosphate-driven proton pump (NbVHP) in Nicotiana benthamiana leaves and studied its functional properties in relation to salt treatment by primarily using patch-clamp, impalement electrodes and pH imaging.

NbVHP overexpression led to higher vacuolar proton currents and vacuolar acidification. After 3 d in salt-untreated conditions, V-PPase-overexpressing leaves showed a drop in photosynthetic capacity, plasma membrane depolarization and eventual leaf necrosis. Salt, however, rescued NbVHP-hyperactive cells from cell death. Furthermore, a salt-induced rise in V-PPase but not of V-ATPase pump currents was detected in nontransformed plants.

The results indicate that under normal growth conditions, plants need to regulate the V-PPase pump activity to avoid hyperactivity and its negative feedback on cell viability. Nonetheless, V-PPase proton pump function becomes increasingly important under salt stress for generating the pH gradient necessary for vacuolar proton-coupled Na+ sequestration.
KW  - cell death
KW  - plasma membrane voltage
KW  - proton pump currents
KW  - salt
KW  - vacuolar pH
KW  - vacuolar proton-ATPase (V-ATPase)
KW  - vacuolar proton-pyrophosphatase (V-PPase)
Y1  - 2018
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-227553
VL  - 219
ER  -