Determination of mannitol sorbitol and myo-inositol in olive tree roots and rhizospheric soil by gas chromatography and effect of severe drought conditions on their profiles.

This study reports a method for the analysis of mannitol, sorbitol and myo-inositol in olive tree roots and rhizospheric soil with gas chromatography. The analytical method consists of extraction with a mixture of dichloromethane:methanol (2:1, v/v) for soil samples and a mixture of ethanol:water (80:20) for root samples, silylation using pyridine, hexamethyldisilazane (HMDS) and trimethylchlorosilane (TMCS). The recovery of mannitol sorbitol and myo-inositol (for extraction and analysis in dichloromethane:methanol and ethanol:water) was acceptable and ranged from 100.3 to 114.7%. The time of analysis was <24 min. Among identified polyols extracted from rhizosphere and roots of olive plants, mannitol was the major compound. A marked increase in mannitol content occurred in rhizosphere and roots of water-stressed plants, suggesting a much broader role of mannitol in stress response based on its ability to act as a compatible solute.