Growth Promotion in Pea Stem Sections. I. Stimulation of Auxin and Gibberellin Action by Alkyl Lipids

Abstract

A method of preparing stable aqueous emulsions of lipids is described. With it many fatty acid esters and related compounds, but not the free acids, are found to enhance the growth promoting action of indoleacetic acid (IAA) and gibberellic acid (GA3). They are active on stem sections from both dwarf and standard peas, providing sugar is supplied also. The specificity of this response is delineated. The lipids are ineffective by themselves, and their synergistic effect on the action of IAA and GA3 is exerted at 10-50 [mu][image] concentrations. Tests of possible mechanisms by which this synergism is exerted do not reveal any connection with well known biochemical pathways, with the possible exception of the cytochromes. Even in the presence of the active lipids, pea sections fail to reach the growth they would attain on the intact plant, indicating that still other growth-limiting factors are involved in pea stem growth.