Physiological Studies on Pea Tendrils

A technique has been devised for the asymmetrical application of ethylene to specific surfaces of plant tissue. 2-Chloroethylphosphonic acid (CEPA) was dissolved in a phosphate buffer (pH 6.5) containing Tween-20 or dimethylsulfoxide as adjuvant. Ethylene evolution from tendrils of Pisum sativum cv. Alaska was greater during coiling than when they were at rest; and via topical application to the ventral surface, CEPA was able to stimulate contact coiling. Within 1 day of application of CEPA, the tendrils showed symptoms of senescence. It is concluded that ethylene participates in the control of contact coiling stimulated by touch, and it is suggested that this control may be exerted via permeability changes in the membranes of the motor cells.