title: A putative 6-transmembrane nitrate transporter OsNRT1.1b plays a key role in rice under low nitrogen.
abstract: OsNRT1.1a is a low-affinity nitrate (NO3 (-) ) transporter gene. In this study, another mRNA splicing product, OsNRT1.1b, putatively encoding a protein with six transmembrane domains, was identified based on the rice genomic database and bioinformatics analysis. OsNRT1.1a/OsNRT1.1b expression in Xenopus oocytes showed OsNRT1.1a-expressing oocytes accumulated (15) N levels to about half as compared to OsNRT1.1b-expressing oocytes. The electrophysiological recording of OsNRT1.1b-expressing oocytes treated with 0.25 mM NO3 (-) confirmed (15) N accumulation data. More functional assays were performed to examine the function of OsNRT1.1b in rice. The expression of both OsNRT1.1a and OsNRT1.1b was abundant in roots and downregulated by nitrogen (N) deficiency. The shoot biomass of transgenic rice plants with OsNRT1.1a or OsNRT1.1b overexpression increased under various N supplies under hydroponic conditions compared to wild-type (WT). The OsNRT1.1a overexpression lines showed increased plant N accumulation compared to the WT in 1.25 mM NH4 NO3 and 2.5 mM NO3 (-) or NH4 (+) treatments, but not in 0.125 mM NH4 NO3 . However, OsNRT1.1b overexpression lines increased total N accumulation in all N treatments, including 0.125 mM NH4 NO3 , suggesting that under low N condition, OsNRT1.1b would accumulate more N in plants and improve rice growth, but also that OsNRT1.1a had no such function in rice plants.
authors.affiliation: Key Laboratory of Plant Nutrition and Fertilization in Low-Middle Reaches of the Yangtze River, Ministry of Agriculture, Nanjing Agricultural University, Nanjing, 210095, China.
authors.forename: Xiaorong
authors.initials: X
authors.lastname: Fan
authors.affiliation: Key Laboratory of Plant Nutrition and Fertilization in Low-Middle Reaches of the Yangtze River, Ministry of Agriculture, Nanjing Agricultural University, Nanjing, 210095, China.
authors.forename: Huimin
authors.initials: H
authors.lastname: Feng
authors.affiliation: Key Laboratory of Plant Nutrition and Fertilization in Low-Middle Reaches of the Yangtze River, Ministry of Agriculture, Nanjing Agricultural University, Nanjing, 210095, China.
authors.forename: Yawen
authors.initials: Y
authors.lastname: Tan
authors.affiliation: Key Laboratory of Plant Nutrition and Fertilization in Low-Middle Reaches of the Yangtze River, Ministry of Agriculture, Nanjing Agricultural University, Nanjing, 210095, China.
authors.forename: Yanling
authors.initials: Y
authors.lastname: Xu
authors.affiliation: Key Laboratory of Plant Nutrition and Fertilization in Low-Middle Reaches of the Yangtze River, Ministry of Agriculture, Nanjing Agricultural University, Nanjing, 210095, China.
authors.forename: Qisong
authors.initials: Q
authors.lastname: Miao
authors.affiliation: Key Laboratory of Plant Nutrition and Fertilization in Low-Middle Reaches of the Yangtze River, Ministry of Agriculture, Nanjing Agricultural University, Nanjing, 210095, China.
authors.forename: Guohua
authors.initials: G
authors.lastname: Xu
mesh_terms: D000818:Animals; D027321:Anion Transport Proteins / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D000091285:Nitrate Transporters; D009584:Nitrogen / Q000172:deficiency* / Q000378:metabolism; D009865:Oocytes / Q000378:metabolism; D012275:Oryza / Q000235:genetics / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D014981:Xenopus
chemical_list: D027321:Anion Transport Proteins; D000091285:Nitrate Transporters; D010940:Plant Proteins; D009584:Nitrogen
keywords: 6-transmembrane transport protein; Nitrate; OsNRT1.1a/b; nitrogen accumulation; overexpression; rice