Details

Autor(en) / Beteiligte

• Beyhl, Diana
• Hörtensteiner, Stefan
• Martinoia, Enrico
• Farmer, Edward E
• Fromm, Jörg
• Marten, Irene
• Hedrich, Rainer

Titel

fou2 mutation in the major vacuolar cation channel TPC1 confers tolerance to inhibitory luminal calcium

Ist Teil von

• The Plant journal : for cell and molecular biology, 2009-06, Vol.58 (5), p.715-723

Ort / Verlag

Oxford, UK: Oxford, UK : Blackwell Publishing Ltd

Erscheinungsjahr

2009

Quelle

Wiley-Blackwell Journals

Beschreibungen/Notizen

• The SV channel encoded by the TPC1 gene represents a Ca²⁺- and voltage-dependent vacuolar cation channel. Point mutation D454N within TPC1, named fou2 for fatty acid oxygenation upregulated 2, results in increased synthesis of the stress hormone jasmonate. As wounding causes Ca²⁺ signals and cytosolic Ca²⁺ is required for SV channel function, we here studied the Ca²⁺-dependent properties of this major vacuolar cation channel with Arabidopsis thaliana mesophyll vacuoles. In patch clamp measurements, wild-type and fou2 SV channels did not exhibit differences in cytosolic Ca²⁺ sensitivity and Ca²⁺ impermeability. K⁺ fluxes through wild-type TPC1 were reduced or even completely faded away when vacuolar Ca²⁺ reached the 0.1-m m level. The fou2 protein under these conditions, however, remained active. Thus, D454N seems to be part of a luminal Ca²⁺ recognition site. Thereby the SV channel mutant gains tolerance towards elevated luminal Ca²⁺. A three-fold higher vacuolar Ca/K ratio in the fou2 mutant relative to wild-type plants seems to indicate that fou2 can accumulate higher levels of vacuolar Ca²⁺ before SV channel activity vanishes and K⁺ homeostasis is impaired. In response to wounding fou2 plants might thus elicit strong vacuole-derived cytosolic Ca²⁺ signals resulting in overproduction of jasmonate.