The compartmentation of ethylene in developing cotyledons of Phaseolus vulgaris L.

Isolated cotyledons of Phaseolus vulgaris L. cv. Canadian Wonder accumulated (14)C2H4 (0.7-1 μl l(-1)) from air to give partition coefficients of 1 to 4, which greatly exceeded the value obtained with steam killed cotyledons (0.05) and with water (0.11). After (14)C2H4 treatment, 98% of the (14)C in the tissue remained as (14)C2H4. The labelled ethylene accumulated by cotyledons was released only slowly (1-10% h(-1)) either in an air stream or into toluene. Heating to 60°C for 2 h, but not freezing and thawing, caused the immediate release of (14)C2H4 from the tissue. Propylene and vinyl chloride competitively inhibited the accumulation of (14)C2H4.Cotyledons emanated endogenous ethylene at a very low rate but after heating (although not freezing and thawing) 13 nl of ethylene per g fresh mass were released within minutes. It was concluded that french bean cotyledons hold ethylene in a compartmented form in sufficient amount to account for at least 200 h of emanation.