A new growth inhibitor, pisumin, involved in light inhibition of epicotyl growth of dwarf peas.

A new growth inhibitor, tentatively named pisumin, which increased under red light and remained at initial level or decreased when dwarf pea (Pisum sativum L. cv Progress No. 9) seedlings were transferred from red light to dark, has been isolated in the form of a colorless powder from light-exposed epicotyls of dwarf peas, and characterized partially as an aliphatic carboxylic acid (molecular weight 284) by spectrometric analyses.Exogenous pisumin inhibited the growth of epicotyl segments of dwarf peas at concentrations higher than 0.1 millimolar in the dark.