African Journal of
Biotechnology

  • Abbreviation: Afr. J. Biotechnol.
  • Language: English
  • ISSN: 1684-5315
  • DOI: 10.5897/AJB
  • Start Year: 2002
  • Published Articles: 12209

Full Length Research Paper

Long-term mannitol-induced osmotic stress leads to stomatal closure, carbohydrate accumulation and changes in leaf elasticity in Phaselous vulgaris leaves

Sameh Sassi1, Samir Aydi1*, Kamel Hessini1, Esther M. Gonzalez2, Cesar Arrese-Igor2 and Chedly Abdelly1
1Laboratoire des Plantes Extrémophiles, Centre de Biotechnologie de Borj Cedria, BP 901, 2050 Hammam Lif, Tunisia. 2Dpto. CC. Medio Natural, Universidad Pública de Navarra, Campus Arrosadía, E-31006 Pamplona, Spain.
Email: [email protected]

  •  Accepted: 17 June 2010
  •  Published: 13 September 2010

Abstract

The effect of long-term osmotic stress was investigated in leaves of two common bean lines, with contrasting tolerance: Flamingo (tolerant) and coco blanc (sensitive). Water relations, organic solute, ion accumulation and amino acids content as well as osmotic adjustment (OA) were studied during an extended exposure to osmotic stress. Osmotic stress was applied by means of 50 mM mannitol for 15 days. At the end of the stress period, both osmotic potential at full turgor (Ψ100) and at turgor loss point (Ψ0) decreased significantly in stressed plants compared with the control. The decrease being greater in the sensitive line, showed a greater OA compared with flamingo. Sugars contents increased in stressed plants and seem to be the major components of osmotic adjustment in stressed common bean leaves. The increase was more marked in coco blanc. Osmotic stress tolerance could thus not be associated with higher OA. The possible role of decreased leaf cell elasticity (εmax) is discussed in relation to osmotic stress tolerance in this species.

 

Key words: Common bean, carbohydrate accumulation, growth, osmotic stress, osmotic adjustment, P-V curve, water relations.

Abbreviation

AWC, Apoplastic water content; DAS, days after seedlings emergence; DW, dry weight; LWP, leaf water potential; OA, osmotic adjustment;PAR, photosynthetic active radiation; P-V curve, pressure-volume curve; RWC,relative water content; SEM, scanning electron microscopy; ΔΨl, degree of osmotic adjustment; ε, tissue elastic modulus; εmax, cell elasticity; Ψ, osmotic potential; Ψ0, osmotic potential at turgor loss point; Ψ100, osmotic potential at full turgor.