Physiological mechanism of increasing lateral roots of Phaseolus coccineus L. under P deficiency

To determine function of IAA in root formation under P deficiency stress, a hydroponic experiment was conducted to study the relationship between IAA-oxidase and root architecture by using exogenous IAA and TIBA, clarifying their specific role in root architecture of Phaseolus coccineus L. under P deficiency. The results show that indole-3-acetic acid has crucial functions in the process of lateral formation by increasing lateral roots, while auxin polar translation inhibitor TIBA has drastic reduction of lateral roots. The activities of IAA metabolismrelated enzymes, IAAO and POD, are regularity in forming process of root system morphogenesis, and the activities of IAAO and POD of root tissues under the P deficiency are higher than those under the P sufficient solution. The exogenous IAA could upregulate the activities of these two enzymes which are significantly restrained by TIBA.