Growth and energy status of arrowhead tubers, pondweed turions and rice seedlings under anoxic conditions

The responses of two aquatic plants, arrowhead (Sagittaria pygmaea Mig.) an d pondweed (Potamogeton distinctus A. Benn), to anoxia were compared with t hose of rice (Oryza sativa L.), Shoot elongation of arrowhead tubers was en hanced at around 1 kPa O-2, whereas that of pondweed turions was slight in air and reached a maximum in the absence of O-2. Anaerobic enhancement of a lcohol dehydrogenase (ADH) activity took place in rice coleoptiles but not in arrowhead and pondweed shoots. Shoots of both arrowhead and pondweed mai ntained a more stable energy status than did the rice coleoptile under anae robic conditions. Total adenylate nucleotide contents of arrowhead and pond weed shoots were constant under anaerobic conditions. Adenylate energy char ge in both shoots remained at a high and stable level of more than 0.8 for at least 8 d. Three forms of ADH from arrowhead shoots were separated by st arch gel electrophoresis, showing that the activity of each ADH form was di fferent under aerobic and anaerobic conditions. The incorporation of S-35-l abelled Cys and Met into soluble proteins in arrowhead shoots showed active protein biosynthesis and an involvement of a special set of polypeptides i n the anaerobiosis.