Abstract
Monocot coleoptiles have been used to investigate IAA production and polar transport. Here, using maize coleoptiles, we show that IAA synthesized at tip region was transported to basal parts in a polar manor by ZmPIN1s. When the tip region was locally treated with NPA and BFA, NPA did not affect distribution of cellular ZmPIN1(s), but BFA caused ZmPIN1(s) to accumulate in cellular aggregation bodies. The inhibitors almost completely suppressed bending in response to gravity, where IAA was accumulated within the tip but decreased in lower regions. In addition, a loss of asymmetric IAA distribution between upper and lower sides was observed. These results indicated that IAA synthesized at the tip and its flow direction are crucial key factors for gravi-curvature. We will also report about the results of chemical genomic approaches using this coleoptile system to screen new compounds affecting IAA biosynthesis, transport and gravi-curvature.
