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Survival and recovery of perennial forage grasses under prolonged Mediterranean drought: II. Water status, solute accumulation, abscisic acid concentration and accumulation of dehydrin transcripts in bases of immature leaves

Published online by Cambridge University Press:  01 November 1998

FLORENCE VOLAIRE ,
HENRY THOMAS ,
NADIA BERTAGNE ,
EMMANUELLE BOURGEOIS ,
MARIE-FRANÇOISE GAUTIER  and
FRANÇOIS LELIÈVRE
FLORENCE VOLAIRE
Affiliation:
Institut National de Recherche Agronomique (INRA), Laboratoire d'Ecophysiologie des Plantes sous Stress Environnementaux, 2 place Viala, F-34060 Montpellier Cedex 01, France
HENRY THOMAS
Affiliation:
Institute of Grassland and Environmental Research, Plas Gogerddan, Aberystwyth, Ceredigion, SY23 3EB, UK
NADIA BERTAGNE
Affiliation:
Institut National de Recherche Agronomique (INRA), Laboratoire d'Ecophysiologie des Plantes sous Stress Environnementaux, 2 place Viala, F-34060 Montpellier Cedex 01, France
EMMANUELLE BOURGEOIS
Affiliation:
INRA, Unité de Biochimie et Biologie Moléculaire des Céréales, 2 place Viala, F-34060 Montpellier Cedex 01, France
MARIE-FRANÇOISE GAUTIER
Affiliation:
INRA, Unité de Biochimie et Biologie Moléculaire des Céréales, 2 place Viala, F-34060 Montpellier Cedex 01, France
FRANÇOIS LELIÈVRE
Affiliation:
Institut National de Recherche Agronomique (INRA), Laboratoire d'Ecophysiologie des Plantes sous Stress Environnementaux, 2 place Viala, F-34060 Montpellier Cedex 01, France
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Abstract

Swards of cocksfoot (cvs KM2, Lutetia) and perennial ryegrass (cvs Aurora, Vigor) were grown under full irrigation or severe (80 d) drought in a field experiment in the South of France. Responses of the bases of immature leaves plus enclosed tissues were made during the drought period and after rewatering.

By the end of the drought, water content had fallen from 3·0 to 0·8 gwater g−1dm, and osmotic potential from −1·0 to −4·5 MPa in all cvs. Measured minerals and water-soluble carbohydrates contributed, respectively, c 19 and 44% to osmotic potential in droughted leaf bases. The drought-sensitive cocksfoot cv. Lutetia was characterized by a large proportion of fructans having a low degree of polymerization (DP=3, 4). As drought progressed, accumulation of dehydrin transcripts and ABA were higher in leaf bases of the sensitive cv. Lutetia than in the resistant cv. KM2.

After rewatering, the water status of immature leaf bases returned to control levels in 1–2 d, and then increased further as leaves began to grow and new tissue was produced. High-DP-fructans remained unchanged in leaf bases of ‘Lutetia’ but were depleted by over 55%, and therefore remobilized, in leaf bases of other cvs after 8 d.

It is concluded that enclosed immature leaf bases survive drought by tolerating a low water status and that changes conventionally associated with desiccation tolerance are expressed most strongly in susceptible plants least able to maintain their water supply.

Keywords

Dactylis glomerata L. (cocksfoot)Lolium perenne L. (ryegrass)osmotic potentialcarbohydratesdehydrin
Type
Research Article
Information
The New Phytologist , Volume 140 , Issue 3 , November 1998 , pp. 451 - 460
Copyright
© Trustees of New Phytologist 1998

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