New Insights to Auxin Signaling through The Use of Small Molecules

Abstract

Elucidating the perception mechanism of auxin has been a long-standing goal in plant biology. To understand the mechanism, studies on the chemical structure and activity relationships of auxin-related small molecules have been done for more than half a century. Today, aided mainly by Arabidopsis genetics, researchers have identified the core complexes for auxin perception, including the auxin receptors TIR1/AFBs, SKP2 and ABP1. Forward chemical screening using auxin response markers has also played an important role in identifying small molecules affecting the auxin-signaling pathways and led to the screening of additional auxin related mutants. This approach has helped in identifying several unique molecular components of the auxin-signaling pathways, and discovering that would have been impossible using traditional screening of mutants against auxin. This review is focused on recently acquired knowledge of multiple auxin signaling pathways and related small compounds that can be used to dissect auxin signal transduction pathways. In addition, the involvement of distinct auxin-signaling machineries during gravity response is discussed.