Abstract
Compared to yeast and animals, membrane trafficking systems are less understood in plants. Arabidopsis thaliana BOR1 is an efflux-type borate (B) transporter required for xylem loading of B under low B condition. BOR1 accumulates at plasma membrane under B limitation and is degraded via endocytosis under high B condition. BOR1 was the first plasma-membrane transporter protein which was shown to be degraded via endocytosis in plants (Takano et al., 2005). To obtain insights into the molecular mechanisms of this regulation, we performed screening for mutants defective in B-dependent degradation of BOR1. In EMS-treated A. thaliana transgenic line carrying CaMV35S-BOR1-GFP, we selected plants showing high GFP fluorescence under high B conditions. Out of 57,150 M2 plants, we isolated several independent mutants and identified the responsible genes by map-based cloning method. Here, we report isolation and characterization of these mutants and the genes.
