低磷胁迫下熊猫豆侧根增多的生理机制研究

采用溶液培养方法，通过外源添加生长素吲哚-3-乙酸（IAA）及生长素极性运输抑制剂2,3,5-三碘苯甲酸（TIBA），研究了低磷胁迫下熊猫豆根系构型与生长素相关代谢酶活性之间的关系，以阐明生长素在低磷胁迫下塑造植物根系构型的作用。结果表明，熊猫豆在低磷胁迫下形成特定根系构型，具体表现为侧根增多。IAA在侧根发生过程中起重要作用，外源IAA可以在一定程度上模拟低磷信号引导的侧根发生，而生长素极性运输抑制剂TIBA则显著抑制侧根发生。根系中生长素代谢相关酶生长素氧化酶（IAAO）和过氧化物酶（POD）活性在根构型形成过程中呈现规律性变化。低磷环境下熊猫豆根系中的IAAO、 POD酶活性均高于正常施磷的处理。外源IAA可以增加这两种酶的活性，而TIBA则能够逆转低磷诱导的IAAO、 POD活性的增加。

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.