Abstract
Boron (B) is essential but excess B is toxic in higher plants. In Arabidopsis, a B efflux transporter, BOR1, which localized preferentially in the plasma membrane of proximal side of root cells, functions for efficient translocation of B from the soil under B limitation condition. However, under enough B condition, the function of BOR1 is considered to be not needed or detrimental. Indeed, the accumulation of BOR1 is rapidly decreased by the ressupply of high levels of B. BOR1 is transferred from the plasma membrane to the vacuole via endocytic pathway. However, it is unknown which intracellular factors are involved in the machinery. We will report a novel factor involved in the machinery and discuss how plant cells effectively regulate B uptake.