STIMULATIVE EFFECT OF HALOGENATED TYROSINE ON ROOT GROWTH OF RICE SEEDLING

Abstract

The effect of iodotyrosine and its related compounds on the root elongation was studied using intact roots of rice seedlings grown on an agar medium and in a culture solution. MIT (3-monoiodotyrosine), DIT (3,5-diiodotyrosine) markedly stimulated the growth of seminal root, but tyrosine itself was not active. Both iodinated amino acids doubled the length of seminal root in comparison with the control when used at the concentration of 10⁻⁵M, where the growth of shoot and crown root was not affected. And above 10⁻⁵M, the development of lateral root and root hairs was inhibited. DBT (3,5-dibromotyrosine) also notably increased the length of seminal root. Potassium iodide did not accelerate the growth of root.