Changes in starch and soluble sugars in relation to the acquisition of desiccation tolerance during maturation of Brassica campestris seed

Abstract. We investigated the onset of desiccation tolerance in developing embryos of Brassica campestris seeds and possible correlated ultrastructural modifications in the radiele cells. Since the acquisition of desiccation tolerance is a long asynchronous process which took 9 d to be achieved, we determined criteria allowing us to separate freshly intact harvested seeds into desiccation intolerant and desication tolerant batches that differed in age by only 2 d. No particular structural modifications were found except a strong depletion of intraplastidial starch (-90%) coincident with the appearance of stachyose and an increase of sucrose (+30%) on the acquisition of desiccation tolerance. As we did not observe an increase of lipid reserves as a consequence, we suggest that these metabolic events can be a key factor towards the acquisition of desiccation tolerance.