An investigation of the seasonal pattern of mannitol content in deciduous and evergreen species of the Oleaceae growing in northern Sicily

In several species of the Oleaceae mannitol accumulates in response to stress. This family comprises both deciduous and evergreen species, and we investigated the role of mannitol in deciduous malacophyll and evergreen sclerophyll species growing under the same conditions in the field. The relationship between mannitol content and changes in rsinfall or temperature was also studied. The mannitol content of leaves of Fraxinus ornus L., F. angustifolia Vahl., Olea europaea L. and Phyllirea media L. was determined by gas chromatography. Rainfall was negatively correlated with the seasonal increase in mannitol in ash. Temperature did not have a direct influence on mannitol content. In Olea and Phillyrea, variations in mannitol content were poorly correlated with rainfall or temperature.