Current address: European Food Safety Authority (EFSA), Largo N. Palli 5/a, 43121 Parma, Italy.
Do pH changes in the leaf apoplast contribute to rapid inhibition of leaf elongation rate by water stress? Comparison of stress responses induced by polyethylene glycol and down-regulation of root hydraulic conductivity
Article first published online: 16 MAY 2011
© 2011 Blackwell Publishing Ltd
Plant, Cell & Environment
Volume 34, Issue 8, pages 1258–1266, August 2011
How to Cite
EHLERT, C., PLASSARD, C., COOKSON, S. J., TARDIEU, F. and SIMONNEAU, T. (2011), Do pH changes in the leaf apoplast contribute to rapid inhibition of leaf elongation rate by water stress? Comparison of stress responses induced by polyethylene glycol and down-regulation of root hydraulic conductivity. Plant, Cell & Environment, 34: 1258–1266. doi: 10.1111/j.1365-3040.2011.02326.x
This work was supported by a doctoral fellowship from INRA to C.E., and grant ANR-05-GPLA-034-02 from the French Agence Nationale de la Recherche to F.T. and T.S.
- Issue published online: 13 JUL 2011
- Article first published online: 16 MAY 2011
- Accepted manuscript online: 7 APR 2011 11:11PM EST
- Received 23 November 2010; received in revised form 17 February2011; accepted for publication 17 February 2011
- Zea mays;
- leaf growth;
- water deficit
We have dissected the influences of apoplastic pH and cell turgor on short-term responses of leaf growth to plant water status, by using a combination of a double-barrelled pH-selective microelectrodes and a cell pressure probe. These techniques were used, together with continuous measurements of leaf elongation rate (LER), in the (hidden) elongating zone of the leaves of intact maize plants while exposing roots to various treatments. Polyethylene glycol (PEG) reduced water availability to roots, while acid load and anoxia decreased root hydraulic conductivity. During the first 30 min, acid load and anoxia induced moderate reductions in leaf growth and turgor, with no effect on leaf apoplastic pH. PEG stopped leaf growth, while turgor was only partially reduced. Rapid alkalinization of the apoplast, from pH 4.9 ± 0.3 to pH 5.8 ± 0.2 within 30 min, may have participated to this rapid growth reduction. After 60 min, leaf growth inhibition correlated well with turgor reduction across all treatments, supporting a growth limitation by hydraulics. We conclude that apoplastic alkalinization may transiently impair the control of leaf growth by cell turgor upon abrupt water stress, whereas direct hydraulic control of growth predominates under moderate conditions and after a 30–60 min delay following imposition of water stress.