Auxins and their analogs are widely used to promote root growth, flower and fruit development, and yield in crops. The action characteristics and application scope of various auxins are different. To overcome the limitations of existing auxins, expand the scope of applications, and reduce side effects, it is necessary to screen new auxin analogs. Here, we identified 3,4-dichlorophenylacetic acid (Dcaa) as having auxin-like activity and acting through the auxin signaling pathway in plants. At the physiological level, Dcaa promotes the elongation of oat coleoptile segments, the generation of adventitious roots, and the growth of crop roots. At the molecular level, Dcaa induces the expression of auxin-responsive genes and acts through auxin receptors. Molecular docking results showed that Dcaa can bind to auxin receptors, among which TIR1 has the highest binding activity. Application of Dcaa at the root tip of the DR5:GUS auxin-responsive reporter induces GUS expression in the root hair zone, which requires the PIN2 auxin efflux carrier. Dcaa also inhibits the endocytosis of PIN proteins like other auxins. These results provide a basis for the application of Dcaa in agricultural practices.

生长素及其类似物广泛用于促进作物的根系生长、花和果实发育以及产量。各种生长素的作用特性和应用范围不同。为了克服现有生长素的局限性，扩大应用范围，减少副作用，有必要筛选新的生长素类似物。在这里，我们鉴定出 3,4-二氯苯乙酸 （Dcaa） 具有生长素样活性，并通过植物中的生长素信号通路发挥作用。在生理水平上，Dcaa 促进燕麦胚芽鞘节段的伸长、不定根的产生和作物根系的生长。在分子水平上，Dcaa 诱导生长素反应基因的表达，并通过生长素受体发挥作用。分子对接结果显示，Dcaa 可与生长素受体结合，其中 TIR1 的结合活性最高。在 DR5：GUS 生长素反应报告基因的根尖施用 Dcaa 可在根毛区诱导 GUS 表达，这需要 PIN2 生长素外排载体。Dcaa 还像其他生长素一样抑制 PIN 蛋白的内吞作用。这些结果为 Dcaa 在农业实践中的应用提供了依据。