Osmotic and salt stress-induced alteration in soluble carbohydrate content in wheat seedlings

The effect of drought and salt stresses on the water soluble carbohydrate content in wheat (Triticum aestivum L.) seedlings was examined to characterize the involvement of major sugar components in the adaptive processes. Hydroponically grown seedlings of four wheat varieties differing in drought and salt tolerance were exposed to consecutive water (polyethylene glycol, PEG) and salinity (NaCl) stresses. Total water-soluble carbohydrate (WSC), glucose, fructose, sucrose, and fructan content of stems (non-photosynthetic tissue) were determined. Tolerant genotypes accumulated more soluble carbohydrate than did sensitive ones. Both ionic and non-ionic stresses increased the concentration of reducing sugars, sucrose, and fructans. Drought tolerant varieties accumulated sucrose to a significantly greater level than did sensitive ones under non-ionic stress condition. Changes in fructan content of plants after transfer from PEG to NaCl containing solutions were genotype dependent, increasing in salt tolerant and decreasing in salt sensitive cultivars. These results indicate that WSC might be a useful marker for selecting genotypes that are more drought or salt tolerant. The type of sugar comprising the increase in WSC appears to be a less reliable marker since the initial response was an increase in monosaccharides and the delayed response was an increase in fructan.