FRUCTAN CONTENT OF WHEAT SEEDLINGS (TRITICUM-AESTIVUM L) UNDER HYPOXIA AND FOLLOWING RE-AERATION

We studied fructan accumulation in wheat seedlings (Triticum aestivum L. cv. Alcedo) caused by oxygen shortage around the root. Plants were cultivated in either nitrogen-flushed or aerated nutrient solution. In response to the nitrogen treatment there was an accumulation of solub le carbohydrates in shoots as well as in roots. The main contribution was due to fructans. The content of fructo-oligosaccharides had been i ncreased five-fold in the roots and seven-fold in the shoots. This is incompatible with the assumption that higher substrate consumption fol lows enhanced fermentation under oxygen shortage. Re-aeration of the n itrogen-flushed nutrient solution resulted in enhanced consumption of stored carbohydrates, mainly of fructans, accompanied by high growth r ates of the roots. The possibility of utilizing fructans quickly if ox ygen is available is a possible advantage for plants adapted to hypoxi a. Particularly however, it is suggested that the low energy requireme nts for sucrose:sucrose fructosyltransferase, allowing fructan synthes is even under oxygen shortage, may improve the fitness of plants to su rvive temporary hypoxia in the rhizosphere.