Science. 1988 Jul 15;241(4863):346-9. doi: 10.1126/science.241.4863.346.
The process of polar auxin transport, central to a plant's auxin relations, can be inhibited by a group of synthetic compounds that apparently act by binding to a plasma membrane protein known as the naphthylphthalamic acid (NPA) receptor. No endogenous ligand to the NPA receptor, capable of affecting polar auxin transport in plants, has yet been found. It is now shown that a group of flavonoids-including quercetin, apigenin, and kaempferol-can specifically compete with [(3)H]NPA for binding to its receptor and can perturb auxin transport in a variety of plant tissues and transport systems in a manner closely paralleling the action of synthetic transport inhibitors. Because the active flavonoids are widely distributed in the plant kingdom and exert their effects at micromolar concentrations approximating likely endogenous levels, they may act as natural auxin transport regulators in plants.
极性生长素运输的过程是植物生长素关系的核心，这一过程可以被一组合成化合物所抑制，这些化合物显然通过与一种称为萘基邻苯二甲酸（NPA）受体的质膜蛋白结合而发挥作用。目前尚未发现能够影响植物中极性生长素运输的 NPA 受体的内源性配体。现在已经表明，一组类黄酮——包括槲皮素、芹菜素和山柰酚——可以特异性地与 [(3)H]NPA 竞争结合其受体，并以类似于合成运输抑制剂的方式扰乱各种植物组织和运输系统中的生长素运输。由于活性类黄酮广泛分布于植物界，并以接近可能的内源性水平的微摩尔浓度发挥作用，因此它们可能在植物中充当天然生长素运输调节剂。
