Relation between germination, trehalose and the status of water in Phycomyces blakesleeanus spores as measured by proton-NMR

Laboratory for Plant Biochemistry, KULeuven, Kardinaal Mercierlaan 92, B-3030 Heverlee, Belgium Centre for Nuclear Magnetism and Radiospectroscopy, Laboratorium voor Vaste Stof Fysica en Magnetisme, KULeuven, Celestijnenlaan 200 D, B-3030 Heverlee, Belgium Interdisciplinary Research Centre, KULeuven, Campus Kortrijk, B-8500 Kortrijk, Belgium ABSTRACT The distribution and properties of the cellular water in sporangiospores of Phycomyces blakesleeanus were investigated using proton-NMR. In dormant spores different classes of water were characterized by a difference in their transverse relaxation times ( T 2 ). The amount of cytoplasmic water was estimated to be as low as about 700 mg (g dry wt) -1 and its small T 2 (18.2 ms) indicated a very limited mobility. About 10 min after induction of germination (by a heat shockor by addition of 0.1 M-acetate), both the content and the mobility of the cytoplasmic water increased sharply. These changes coincided with a rapid breakdown of most of the cellular trehalose and with the production (and leakage from the spores) of large amounts of glycerol. The role of these biochemical changes is discussed in relation to the water status of the spores.