Gibberellic acid and indole acetic acid compete in ethylene promoted abscission

Summary Gibberellic acid inhibition of betacyanin biosynthesis has been studied in Amaranthus caudatus L. using the pigment precursors L-tyrosine and L-dihydroxyphenylalanine. Precursors fed to gibberellic acid (GA) treated seedlings completely recovered betacyanin synthesis while the GA induced growth enhancement remained unaltered. Inhibition of betacyanin biosynthesis by GA is related to depletion of metabolites/amino acids and their diversion to support changed pattern of metabolism leading to growth.Abbreviations GA gibberellic acid - L-DOPA L-dihydroxyphenylalanine - Pr phytochrome red absorbing form - Pfr phytochrome, far-red absorbing form