IC4R  Rice Literature Database

High silicon accumulation in the shoot is required for down-regulating the expression of Si transporter genes in rice.

Rice requires high silicon (Si) for its high and sustainable yield. The efficient uptake of Si in rice is mediated by two transporters erm' data-tid='102' href='#term-102'>OsLsi1 and OsLsi2, which function as influx and efflux transporters, respectively. Our previous studies showed that the mRNA expression levels of these traerm' data-tid='104' href='#term-erm' data-tid='106' href='#term-106'>104'>nsporter genes were down-regulated by Si. Herein we investigaterm' data-tid='108' href='#term-108'>ed the mechanism underlying regulation of OsLsi1 and OsLsi2 expression. There was a negative correlation between the expression level of OsLsi1 and OsLsi2 and shoot Si accumulation when the rice seedlings were exposed to different Si supply conditions. A split root experiment showed that the expression of both OsLsi1 and OsLsi2 was also down-regulated in half the rootsa> without direct Si exposure when the other half roots were exposed to Si. Analysis with transgenic rice carrying different lengths of OsLsi1 promoter regions fused with GFP as a reporter gene revealed that the region responsible for Si response of OsLsi1 expression is present between -327 to -292 in the promoter. However, this region was not associated with the tissue and cellular localization of OsLsi1. In conclusion, the Si-induced down-regulation of Si transporter genes is controlled by shoot Si, not root Si, and that the region between -327 to -292 in the OsLsi1 promoter is involved in this regulation of OsLsi1 expression in rice.