Inhibition of Plant Growth by Protoanemonin and Coumarin, and Its Prevention by Bal

Abstract

A study is reported of the action of coumarin and protoanemonin on the growth of 2 standard objects[long dash]sections of Avena coleoptiles elongating in auxin and sucrose, and slit internodes of Pisum stems curving in auxin alone. Both lactones inhibit these growth processes, the protoanemonin being 10-30 times the more active. At subinhibiting concns. the growth is promoted in each case. The inhibition is clearly prevented by the addition of dimercap-topropanol, BAL, at concns, below 3.10[long dash]4[image]. It is concluded that coumarin and protoanemonin inhibit growth through reacting with a sulfhydryl enzyme, and that this enzyme is normally a limiting factor in growth, and is very probably the same as that inhibited by iodoacetate and arsenite.