Reference "An efflux transporter of silicon in rice"

Reference ID

11633

Title

An efflux transporter of silicon in rice

Source

Nature, 2007, vol. 448, pp. 209-212

Authors (8)

Ma-J-F	Yamaji-N
Mitani-N	Tamai-K
Konishi-S	Fujiwara-T
Katsuhara-M	Yano-M

Abstract

Silicon is an important nutrient for the optimal growth and sustainable
production of rice. Rice accumulates up to 10% silicon in the shoot, and this
high accumulation is required to protect the plant from multiple abiotic and
biotic stresses. A gene, Lsi1, that encodes a silicon influx transporter has
been identified in rice. Here we describe a previously uncharacterized gene, low
silicon rice 2 (Lsi2), which has no similarity to Lsi1. This gene is
constitutively expressed in the roots. The protein encoded by this gene is
localized, like Lsi1, on the plasma membrane of cells in both the exodermis and
the endodermis, but in contrast to Lsi1, which is localized on the distal side,
Lsi2 is localized on the proximal side of the same cells. Expression of Lsi2 in
Xenopus oocytes did not result in influx transport activity for silicon, but
preloading of the oocytes with silicon resulted in a release of silicon,
indicating that Lsi2 is a silicon efflux transporter. The identification of this
silicon transporter revealed a unique mechanism of nutrient transport in plants:
having an influx transporter on one side and an efflux transporter on the other
side of the cell to permit the effective transcellular transport of the
nutrients.