No influence of the embryonic axis on the development of diamine oxidase in pea cotyledons.

A reexamination has been made for the supposed regulation of pea (Pisum sativum cv Alaska) cotyledonary diamine oxidase (EC 1.4.3.6) activity by the embryonic axis. When dry cotyledons from which the embryo and testa have been removed surgically are imbibed by soaking in water, there is little increase of the enzyme activity during subsequent incubation on filter paper. However, if the dry cotyledons are imbibed and maintained on filter paper from the first, the increase of the enzyme activity is similar to that in the intact seedling. Thus, rapid imbibition of the isolated dry cotyledons is responsible for repression of enzyme development, and a role for the axis need not be invoked.