Abstract
Arabidopsis thaliana BOR1 is an efflux-type borate transporter required for xylem loading of boron(B) under low B condition. BOR1 accumulates at plasma membrane under B limitation, and is degraded under high B condition.
In the present study, we report the generation of the transgenic Arabidopsis tolerant to excess B by overexpression of BOR4, one of the six BOR1 paralogs present in the Arabidopsis genome.
Transgenic A.thaliana lines expressing BOR4 under the control of CaMV 35S RNA promoter were generated. Immunoblot analysis showed that BOR4-GFP accumulation was not greatly changed upon high B supply. When they were grown in solid medium containing toxic levels of B, six independent transgenic lines showed improvement of growth compared to the wild type plants.
These results indicate that BOR4 has a distinct character from BOR1 in terms of protein accumulation and is capable of conferring extremely high B tolerance to Arabidopsis.
