The stimulation of cell extension by ethylene and auxin in aquatic plants.

Elongation of the shoots of three aquatic plants (Hydrocharis morsus-ranae, Regnellidium diphyllum and Ranunculus sceleratus) is stimulated by treatment with ethylene or IAA. The effects of the two hormones are additive, and experiments with an ethylene biosynthesis inhibitor and silver ions indicate that the mechanisms by which ethylene and IAA stimulate growth may be different. Hydrocharis and Ranunculus leaf discs synthesize [(14)C]ethylene from [(14)C]methionine, but no [(14)C]ethylene is formed by Regnellidium, suggesting the existence of an alternative pathway of ethylene biosynthesis in the fern.