Poster: Root biology

Abs # 699: Involvement of ARM2 in the uptake of Indole-3-butyric acid in rice (Oryza sativa L.)

Presenter:	Chhun, Tory , tsurumis@scitec.kobe-u.ac.jp
Authors	Chhun, Tory  (A)   Taketa, Shin  (A)   Tsurumi, Seiji  (B)   Ichii, Masahiko  (A)
Affiliations:	(A): Faculty of Agriculture, Kagawa University (B): Radioisotope Research Center, Kobe University

Auxin influx and efflux carriers are involved in regulating plant growth and development. Several genes responsible for the influx and efflux of indole-3-acetic acid (IAA) have been identified in Arabidopsis. Here we show that a mutant in rice (Oryza sativa L.) arm2, which was previously found to be defective in 2,4-dichlorophenoxyacetic acid (2,4-D) uptake, is also involved in the uptake of a natural-occurring auxin indole-3-butyric acid (IBA). arm2 roots exhibit a reduced accumulation of IBA but not IAA. Furthermore, arm2 roots were resistant to IBA and responded normally to IAA. These results suggest that at least two distinct auxin influx carriers are involved in regulating plant growth and development. It is interesting to note that arm2 roots are defective in lateral root formation while normal in root gravity response, indicating that endogenous IBA plays a pivotal role in lateral root formation.