Content of water soluble carbohydrates under oxygen deprivation in plants with different flooding tolerance

We investigated the carbohydrate concentration of plant species naturally growing in habitats with a high risk of oxygen shortage (Senecio aquaticus Hill,Myosotis palustris (L.) L. em.Rchb) and congeneric species from drier sites (Senecio jacobaea L.,Myosotis arvensis (L.)Hill) Plants from the four species were cultivated in either nitrogen-flushed or aerated nutrient solution. Following oxygen shortage in the root environment a two—fourfold increase of carbohydrate content was found in the roots as well as in the shoots of the species examined. Although, the tendency in the response of both genera to the hypoxic conditions in the nutrient solution was the same, there were differences in concentration and composition of the water soluble carbohydrates. The flooding tolerantSenecio aquaticus accumulated the highest amounts of carbohydrates, in particular fructans (nearly 60% of the soluble carbohydrates, compared with 30% under aerated conditions). The increasing amount of sugars found under hypoxia-inducing conditions proved that substrate availability was not the limiting factor for survival under wetland conditions.