EFFECT OF 5-AMINOLEVULINIC ACID ON BIOGENESIS OF BARLEY ETIOPLASTS

We investigated the effect of high concentrations (10-60 mM) of 5-aminolevulinic acid (ALA) on accumulation of protochlorophyllide and development of the membrane system of etioplasts in post-etiolated leaves of barley (Hordeum vulgare L.). In a concentration greater than 30 mM, ALA led to a stepwise increase in the amount of protochlorophyllide resynthesized in the dark, which is correlated with a stepwise increase in overall length of prothylakoids on ultratonic sections of etioplasts. It is hypothesized that stepwise increase of these values occurs in proportion to size of the golden section (1.618...). The hypothesis is discussed that some molecules of ALA are utilized for cytokinin synthesis when high levels of it are present in plants.