Abstract
Arabidopsis BOR1 is an efflux transporter of boron. Among six BOR1 paralogs present in Arabiodpsis genome, we studied role of BOR2 in B transport. Expression of BOR2 resulted in reduction in B concentration of yeast cells. It suggests that BOR2 encode an efflux-type B transporter, similar to the case of BOR1. Transgenic Arabidopsis lines carrying T-DNA in BOR2 showed growth retardation compared to wild type plants at low boron supply. Root cell elongation was severely inhibited under low boron supply in these lines. Transgenic Arabidopsis expressing GUS under control of the promoter has revealed that BOR2 are expressed in root tip, cortex cells in roots. We propose that this transporter exports B out of the cells into the apoplasm for effective formation of RGII-B dimer for cell elongation.
