Abstract
Boron is an essential element for plant growth with a very narrow window between deficiency and toxicity. Arabidopsis BOR1 is a boron exporter for xylem loading essential for protecting shoots from boron deficiency. Here we report the regulation of BOR1 by boron availability.
Uptake studies using stable isotopes of boron indicated that the active xylem loading of boron by BOR1 is inducible upon boron starvation. However, quantitative RT-PCR study showed that mRNA level of BOR1 was not significantly affected by boron conditions. In contrast, western analysis using transgenic plants expressing BOR1-GFP fusion protein under control of 35S promoter showed that BOR1-GFP protein accumulated upon boron starvation and the response was reversible upon resupply of boron.
The results suggest that BOR1 is regulated by boron availability at translational/post-translational levels to cope with boron deficiency and toxicity.
