THE OCCURRENCE OF TREHALOSE IN THE LEAVES OF THE DESICCATION-TOLERANTANGIOSPERM MYROTHAMNUS-FLABELLIFOLIUS WELW

Although the disaccharide trehalose predominates in a wide variety of desiccation-tolerant lower organisms, including some lower vascular pl ants, it is rare in higher vascular plants. Sucrose is suggested to ha ve an analogous role to trehalose in stabilizing the membranes of desi ccation-tolerant seeds and pollen of angiosperms. In the present study , both sucrose and trehalose were identified by capillary gas chromato graphy and thin layer chromatography in methanolic extracts of the lea ves of the desiccation-tolerant angiosperm Myrothamnus flabellifolius Welw. Levels of sucrose in hydrated leaves were 29.3 +/- 7.5 mg g-1 dr y weight and those of trehalose 26.0 +/- 7.2 mg g-1 dry weight. In des iccated leaves trehalose levels increased slightly (34.7 +/- 4.3 mg g- 1 dry weight) in contrast to a marked increase in sucrose levels in de siccated leaves (56.5 +/- 6.6 mg g-1 dry weight). It is suggested that the combined sucrose and trehalose contents of the leaves of M. flabe llifolius are probably sufficient to account for membrane stabilizatio n in the desiccated state, as explained by the water replacement hypot hesis.