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 soluble carbohydrates in shoots as well as in roots. The main contribution was due to fructans. The content of fructo-oligosaccharides had been increased five-fold in the roots and seven-fold in the shoots. This is incompatible with the assumption that higher substrate consumption follows enhanced fermentation under oxygen shortage. Re-aeration of the nitrogen-flushed nutrient solution resulted in enhanced consumption of stored carbohydrates, mainly of fructans, accompanied by high growth rates of the roots. The possibility of utilizing fructans quickly if oxygen is available is a possible advantage for plants adapted to hypoxia. Particularly however, it is suggested that the low energy requirements for sucrose: sucrose fructosyl transferase, allowing fructan synthesis even under oxygen shortage, may improve the fitness of plants to survive temporary hypoxia in the rhizosphere.