Is there a role for oligosaccharides in seed longevity? An assessment of intracellular glass stability

We examined whether oligosaccharides extend seed longevity by increasing th e intracellular glass stability. For that purpose, we used a spin probe tec hnique to measure the molecular mobility and glass transition temperature o f the cytoplasm of impatiens (Impatiens walleriana) and bell pepper (Capsic um annuum) seeds that were osmo-primed to change oligosaccharide content an d longevity. Using saturation transfer electron paramagnetic resonance spec troscopy, we found that the rotational correlation time of the polar spin p robe 3-carboxy-proxyl in the cytoplasm decreased, together with longevity, as a function of increasing seed water content, suggesting that longevity m ay indeed be regulated by cytoplasmic mobility. Osmo-priming of the seeds r esulted in considerable decreases in longevity and oligosaccharide content, while the sucrose content increased. No difference in the glass transition temperature was found between control and primed impatiens seeds at the sa me temperature and water content. Similarly, there was no difference in the rotational motion of the spin probe in the cytoplasm between control and p rimed impatiens and bell pepper seeds. We therefore conclude that oligosacc harides in seeds do not affect the stability of the intracellular glassy st ate, and that the reduced longevity after priming is not the result of incr eased molecular mobility in the cytoplasm.