Osmotic and Salt Stresses Induced Differential Alteration in Water-Soluble Carbohydrate Content in Wheat Seedlings

Abstract

Water-soluble carbohydrates contributing to genotypic differences in response to consecutive drought and salinity stresses in wheat seedlings were investigated. Total water-soluble carbohydrate, glucose, fructose, sucrose, and fructan contents and the distribution of degree of polymerization fructans were measured in wheat seedlings exposed to 18% poly(ethylene glycol) (PEG)-induced drought stress followed by an equiosmolar salinity. Tolerant genotypes accumulated higher soluble carbohydrate levels than the sensitive ones. Both ionic and nonionic stresses increased the percentage distribution of reducing sugars. The concentration of the principal component of soluble carbohydrate content increased in response to drought stress and, conversely, mostly decreased due to salt stress. PEG-induced fructan accumulation was highest in leaves and showed a positive correlation with the drought tolerance of the varieties. Fructan content in stems increased in tolerant genotypes but decreased in sensitive ones under NaCl treatment. Increment of polyfructan percentage distribution was greater in tolerant varieties than in sensitive ones. Keywords: Carbohydrates; drought; fructan; salinity; osmotic stress; wheat (Triticum aestivum L.)