title: Increased nitrogen-use efficiency in transgenic rice plants over-expressing a nitrogen-responsive early nodulin gene identified from rice expression profiling.
abstract: Development of genetic varieties with improved nitrogen-use efficiency (NUE) is essential for sustainable agriculture. In this study, we developed a growth system for rice wherein N was the growth-limiting factor, and identified N-responsive genes by a whole genome transcriptional profiling approach. Some genes were selected to test their functionality in NUE by a transgenic approach. One such example with positive effects on NUE is an early nodulin gene OsENOD93-1. This OsENOD93-1 gene responded significantly to both N induction and N reduction. Transgenic rice plants over-expressing the OsENOD93-1 gene had increased shoot dry biomass and seed yield. This OsENOD93-1 gene was expressed at high levels in roots of wild-type (WT) plants, and its protein product was localized in mitochondria. Transgenic plants accumulated higher concentrations of total amino acids and total N in roots. A higher concentration of amino acids in xylem sap was detected in transgenic plants, especially under N stress. In situ hybridization revealed that OsENOD93-1 is expressed in vascular bundles, as well as in epidermis and endodermis. This work demonstrates that transcriptional profiling, coupled with a transgenic validation approach, is an effective strategy for gene discovery. The knowledge gained from this study could be applied to other important crops.
authors.affiliation: Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada N1G 2W1.
authors.forename: Yong-Mei
authors.initials: YM
authors.lastname: Bi
authors.forename: Surya
authors.initials: S
authors.lastname: Kant
authors.forename: Joseph
authors.initials: J
authors.lastname: Clarke
authors.forename: Joseph
authors.initials: J
authors.lastname: Clark
authors.forename: Satinder
authors.initials: S
authors.lastname: Gidda
authors.forename: Feng
authors.initials: F
authors.lastname: Ming
authors.forename: Jianyao
authors.initials: J
authors.lastname: Xu
authors.forename: Amanda
authors.initials: A
authors.lastname: Rochon
authors.forename: Barry J
authors.initials: BJ
authors.lastname: Shelp
authors.forename: Lixin
authors.initials: L
authors.lastname: Hao
authors.forename: Rong
authors.initials: R
authors.lastname: Zhao
authors.forename: Robert T
authors.initials: RT
authors.lastname: Mullen
authors.forename: Tong
authors.initials: T
authors.lastname: Zhu
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Rothstein
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000378:metabolism; D001483:Base Sequence; D018533:Biomass; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D018745:Genome, Plant; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009584:Nitrogen / Q000378:metabolism*; D020411:Oligonucleotide Array Sequence Analysis; D012275:Oryza / Q000235:genetics / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D018517:Plant Roots / Q000378:metabolism; D018520:Plant Shoots / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D018749:RNA, Plant / Q000235:genetics; D012639:Seeds / Q000378:metabolism; D052584:Xylem / Q000378:metabolism
chemical_list: D000596:Amino Acids; D008565:Membrane Proteins; D010940:Plant Proteins; D018749:RNA, Plant; C045625:nodulin; D009584:Nitrogen