Differential gene expression of two outward-rectifying shaker-like potassium channels OsSKOR and OsGORK in rice

Abstract

Shaker-like potassium channels are highly conserved voltage-dependent ion channels in plants. Rice, a monocot model plant, has similar numbers of shaker-like potassium channels as Arabidopsis. Although several inward-rectifying potassium channels have been identified, no outward-rectifying potassium channels have yet been reported for rice. Here, we identified two outward-rectifying shaker-like potassium channels in rice, with high amino acid sequence similarities to Arabidopsis stelar K+ outward rectifier (SKOR) and guard cell outward rectifying K+ channel (GORK). To characterize these channels we monitored their expression patterns in several tissues. qRTPCR and promoter-GUS analysis showed that OsSKOR is expressed in root vascular tissues, flower, and seed scutellum. OsGORK was expressed to some degree in most tissues, such as leaf blade, node, leaf sheath and root, but at high levels in flowers. This is the first report characterizing rice outward-rectifying potassium channels and contributes to understanding the regulation of potassium homeostasis in monocot plants.