Life Science Seminar
 
▶ Subject : Influx and efflux transporters of silicon in plants

▶ Speaker : Jian Feng Ma
             (Institute of Plant Science and Resources, Okayama University)

▶ Date :  4:00PM/ Oct. 14(Fri)/2011

▶ Place :  Aditorium(1F), Postech Biotech Center
 
*Abstract
Silicon (Si), the most abundant minerals in soil, is a beneficial element for plant growth.  Silicon deposited on different tissues protects the plants from biotic and abiotic stresses.    We have identified both influx and efflux transporters of silicon in different plant species, which are involved in the uptake and distribution of silicon.  Lsi1, belonging to NIP group of the aquaporin family, is an influx transporter.  It is responsible for the uptake of Si from soil into the root cells in both dicots and monocots although its expression patterns and cellular localization differ with plant species.  Lsi2 is responsible for the subsequent transport of Si out of the root cells towards the stele.  Lsi1 and Lsi2 are polarly localized at the distal and proximal sides, respectively, of both exodermis and endodermis in rice root.  Silicon in the xylem sap is unloaded by Lsi6, a homolog of Lsi1 in rice.  At reproductive stage of rice, Lsi6 is strongly expressed at the xylem transfer cells at the node I with polarity facing toward the xylem vessel in rice.  Lsi3, a Si efflux transporter like Lsi2, is expressed at several parenchyma cell layers located between the xylem transfer cells and the diffuse vascular bundles.  Knockout of Lsi6 resulted in decreased Si accumulation in the panicles, but increased accumulation in the flag leaf.  These results indicate that both Lsi6 and Lsi3 are required for the inter-vascular transfer of Si; Lsi6 functions as an influx transporter, unloading Si from transpirational flow in enlarged vascular bundles, while Lsi3 likely functions as an efflux transporter, reloading Si to diffuse vascular bundles.

☎ Inquiry : Prof. Youngsook Lee(279-2296)