Molecular dissection of boron transport in Arabidopsis thaliana

摘要

Boron deficiency and toxicity are world-wide problems. Understanding molecular mechanisms that control boron uptake and transport is important for an improved agricultural production on B problem soils. Boron has long been considered to be transported passively in plants, however, recent studies indicated that plants are capable of accumulating B from nutrient solution under B-deficient conditions. We have been studying molecular mechanisms of B uptake and transport using A. thaliana. With the use of bor1-1 mutant plants, we identified the first B transporter, BOR1, in the living systems. BOR1 is a B exporter expressed in pericycle cells and required for efficient B loading of the xylem. BOR1 accumulation is regulated by B availability in the environment, i.e., it accumulates only under limited B supply. Among the six homologs of BOR1 in the A. thaliana genome, several of them are capable of transporting B and they seem to share functions of B transport with BOR1. We also identified a membrane protein that is important for B uptake. With the use of these molecular tools, we are exploring the possibility to generate plants that tolerate high or low B conditions.