Sugars are reputed to protect membranes in dehydrated desiccation-tolerant organisms, such as seeds and pollens. They interact with the polar headgroups of the membrane phospholipids and control the gel-to-liquid crystalline transition temperature (Tm). Because the amount of sugar may be insufficient for full interaction in some organisms, another mechanism of membrane protection was sought. A mechanism is proposed that is based on the partitioning of amphiphilic compounds into membranes depending on the water available. This mechanism was tested (principally in experiments with Typha latifolia pollen) with an amphiphilic nitroxide spin probe, using EPR spectroscopy. It was found that, apart from the spin probe, endogenous amphiphiles may also partition into membranes during dehydration. The amphiphiles reduce the dehydration-induced increase of Tm and cause fluidization. The advantages and disadvantages of such a mechanism are discussed. The proposed mechanism is extremely effective at automatically inserting amphiphilic antioxidants into membranes with dehydration, which could promote desiccation tolerance and extend storage longevity.
|Title of host publication||Seed biology: Advances and Applications|
|Editors||M. Black, K.J. Bradford, J. Vasques-Ramos|
|Place of Publication||Wallingford|
|Publication status||Published - 2000|