Ethylene and carbon dioxide as mediators in the response of the bean hypocotyl hook to light and auxins

Abstract

Ethylene inhibits hook opening in the bean hypocotyl and at high concentrations induces closure of the hook. Indoleacetic acid and 2,4-dichlorophenoxyacetic acid, whose inhibitory effect on hook opening resembles that of ethylene, stimulate ethylene production from the hook tissue, and this ethylene production is physiologically active in inhibiting hook opening. It is concluded that the inhibition of opening by auxin is due at least in a major part to auxin-induced ethylene production by the hook tissue.