Plant steroid hormones.

After a brief survey of the literature on the recently discovered brassinolide, some of our results with corticosteroids are given. A number of structural requirements of corticosteroids were deduced in a bioassay involving elongation growth and lateral root formation. To explain the activity of glucocorticoids, the involvement of a receptor protein is suggested as well as an enhanced RNA synthesis. However, the structural requirements found are not applicable to experiments on adventitious root formation, implying a different mode of action of corticosteroids in this test system.