Overexpression of a pH-sensing nitrate transporter in the membrane to increase rice crop yields
【摘要】：Cellular pH homeostasis is fundamental for life and all cells adapt to maintain this balance. In plants the chemical form of nitrogen supply,nitrate and ammonium,is one of the cellular p H dominators. We report that the rice nitrate transporter OsNRT2.3 is transcribed into two spliced isoforms with natural variation in their expression ratio. One splice form,OsNRT2.3b is plasma membrane located mainly expressed in the phloem,and which has a regulatory motif on the cytosolic side that acts to switch nitrate transport activity on or off by a p H sensing mechanism. High OsNRT2.3b expression in rice enhances the p H buffering capacity of the plant,increasing N,Fe and P uptake. I n field trials,increased expression of OsNRT2.3b improved grain yield and nitrogen use efficiency(NUE) by 40%. These results indicate that p H sensing by the rice nitrate transporter OsNRT2.3b is important for plant adaption to varied N supply forms and can provide a target of improving NUE.