Molecular mobility in the cytoplasm: An approach to describe and predict lifespan of dry germplasm

Molecular mobility is increasingly considered a key factor influencing stor age stability of biomolecular substances, because it is thought to control the rate of detrimental reactions responsible for reducing the shelf life o f, for instance, pharmaceuticals, food, and germplasm. We investigated the relationship between aging rates of germplasm and the rotational motion of a polar spin probe in the cytoplasm under different storage conditions usin g saturation transfer electron paramagnetic resonance spectroscopy. Rotatio nal motion of the spin probe in the cytoplasm of seed and pollen of various plant species changed as a function of moisture content and temperature in a manner similar to aging rates or longevity. A linear relationship was es tablished between the logarithms of rotational motion and aging rates or lo ngevity. This linearity suggests that detrimental aging rates are associate d with molecular mobility in the cytoplasm. By measuring the rotational cor relation times at low temperatures at which experimental determination of l ongevity is practically impossible, this linearity enabled us to predict vi gor loss or longevity. At subzero temperatures, moisture contents for maxim um life span were predicted to be higher than those hitherto used in geneba nks, urging for a reexamination of seed storage protocols.