Abstract
Arabidopsis thaliana BOR1 is a borate exporter and is essential for efficient boron(B) translocation under low B conditions. In the root tip cells of P35S:BOR1-GFP plants, BOR1-GFP accumulated in the plasma membrane under B limitation, and was transferred to the endosome and then the vacuole for degradation upon high B supply (Takano et al., 2005).
On the other hand, Arabidopsis thaliana BOR4 was suggested to take part in B export from plant roots under B excess (Miwa et al., this meeting). In the root tip cells of P35S:BOR4-GFP plants, BOR4-GFP still accumulated in the plasma membrane upon high B supply.
To identify domains and motifs important for the different response to B availability, we conducted domain-swapping between BOR1 and BOR4 and also site-directed mutagenesis of potential endocytosis signal motifs in BOR1. We report B-dependent localization of these transporters and discuss the mechanisms of B-dependent trafficking of borate transporters.
