Abstract
Auxin is a master regulators of plant development including apical dominance, gravitropism, and phototropism. The auxin polar transport establish an asymmetric auxin distribution to respond environmental stimulus and consequently modulate the auxin responses of cells. Therefore, the auxin transport system plays a crucial role in plant development. Auxin distribution is regulated by the active transport by auxin influx and efflux carriers/transporters localized in plant cell membrane. Auxin influx transporters, AUX/LAX importers, efflux carrier proteins, PIN and auxin transporters ABCB/PGP are thought to coordinately modulate the endogenous auxin gradient to regulate plant development. Therefore, the dynamic of intracellular auxin distribution are important for the understanding of molecular mechanism for auxin transport system. The radio-labeled IAA and the indirect auxin-responsive reporter marker were utilized to study the auxin distribution and its polar transport. We here demonstrate the new fluorescent auxin analogs that is substrate for auxin transporters, but is unrecognized as auxin by TIR1/AFB auxin receptors. This new fluorescent auxin analogue function as auxin specific for polar auxin transport system, but not for auxin signaling. This fluorescent tools would mimic the cellular IAA distribution and indirectly visualize the dynamic of auxin movement mediated by auxin polar transport system.
