Evidence for “gibberellin-like” activity of coumarin

Abstract

The existing body of information defines some regulatory functions to secondary metabolites like coumarin (COU). Experience and some experimental results in our laboratory tempted us to test a GA-like activity of COU. Experiments were conducted with endospermic (de-embryonated) and embryonic wheat half grains treated with different concentrations of COU, for different time courses, alone or in combination with the GA-biosynthesis inhibitor paclobutrazol (P). Results showed that treatment with COU caused stimulation of amylase synthesis and secretion from aleurone layer cells. P did not affect synthesis but slightly reduced excretion of amylase. However, germination percentage of intact wheat grains and seedling growth were inhibited by COU in a concentration-dependent manner. This indicates that COU has some GA-like effect, and also affects other aspects of germination and seedling establishment. This GA-like effect was also confirmed by the observed increase in elongation of wheat seedlings second leaf sheath and pea stem when treated with COU. These potential regulatory roles of COU may indicate that secondary metabolites have more important roles during different plant developmental processes.