Effect of sodium chloride on the response of the halophyte species Sesuvium portulacastrum grown in mannitol-induced water stress.
Sesuvium portulacastrum is a halophytic species well adapted to salinity and drought. In order to evaluate the physiological impact of salt on water deficit-induced stress response, we cultivated seedlings for 12 days, in the presence or absence of 100 mmol l(-1) NaCl, on a nutrient solution containing either 0 mmol l(-1) or 25 mmol l(-1) mannitol. Mannitol-induced water stress reduced growth, increased the root/shoot ratio, and led to a significant decrease in water potential and leaf relative water content, whereas leaf Na(+) and K(+) concentrations remained unchanged. The addition of 100 mmol l(-1) NaCl to 25 mmol l(-1) mannitol-containing medium mitigated the deleterious impact of water stress on growth of S. portulacastrum, improved the relative water content, induced a significant decrease in leaf water potential and, concomitantly, resulted in enhancement of overall plant photosynthetic activity (i.e. CO(2) net assimilation rate, stomatal conductance). Presence of NaCl in the culture medium, together with mannitol, significantly increased the level of Na(+) and proline in the leaves, but it had no effect on leaf soluble sugar content. These findings suggest that the ability of NaCl to improve plant performance under mannitol-induced water stress may be due to its effect on osmotic adjustment through Na(+) and proline accumulation, which is coupled with an improvement in photosynthetic activity. A striking recovery in relative water content and growth of the seedlings was also recorded in the presence of NaCl on release of the water stress induced by mannitol.
Slama
Inès
I
Laboratoire d'Adaptation des Plantes aux Stress Abiotiques, Centre de Biotechnologie, Technopole de Borj Cédria, BP 901, Hammam-Lif, Tunisia.
Ghnaya
Tahar
T
Messedi
Dorsaf
D
Hessini
Kamel
K
Labidi
Nahla
N
Savoure
Arnould
A
Abdelly
Chedly
C
D035722:Aizoaceae / Q000187:drug effects* / Q000254:growth & development*; D002241:Carbohydrates; D002245:Carbon Dioxide / Q000378:metabolism; D005740:Gases; D008353:Mannitol / Q000494:pharmacology*; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects / Q000378:metabolism; D011188:Potassium / Q000378:metabolism; D011392:Proline / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D012965:Sodium Chloride / Q000494:pharmacology*; D014867:Water / Q000378:metabolism*
D002241:Carbohydrates; D005740:Gases; D014867:Water; D002245:Carbon Dioxide; D008353:Mannitol; D012965:Sodium Chloride; D011392:Proline; D012964:Sodium; D011188:Potassium