Increased nitrogen-use efficiency in transgenic rice plants over-expressing a nitrogen-responsive early nodulin gene identified from rice expression profiling

• Published in: Plant, cell and environment Vol. 32; no. 12; pp. 1749 - 1760
• Main Authors: BI, YONG-MEI, KANT, SURYA, CLARK, JOSEPH, GIDDA, SATINDER, MING, FENG, XU, JIANYAO, ROCHON, AMANDA, SHELP, BARRY J, HAO, LIXIN, ZHAO, RONG, MULLEN, ROBERT T, ZHU, TONG, ROTHSTEIN, STEVEN J
• Format: Journal Article
• Language: English
• Published: Oxford, UK Oxford, UK : Blackwell Publishing Ltd 01.12.2009; Blackwell Publishing Ltd; Blackwell
• Subjects: Amino Acid Sequence; amino acids; Amino Acids - metabolism; Base Sequence; Biological and medical sciences; Biomass; Fundamental and applied biological sciences. Psychology; Gene Expression Profiling; Gene Expression Regulation, Plant; Genome, Plant; Membrane Proteins - genetics; Membrane Proteins - metabolism; Molecular Sequence Data; Nitrogen - metabolism; nitrogen induction; nitrogen limitation; nitrogen reduction; Oligonucleotide Array Sequence Analysis; Oryza - genetics; Oryza - metabolism; Plant Proteins - genetics; Plant Proteins - metabolism; Plant Roots - metabolism; Plant Shoots - metabolism; Plants, Genetically Modified - genetics; Plants, Genetically Modified - metabolism; RNA, Plant - genetics; Seeds - metabolism; transcriptional profiling; Xylem - metabolism; transcriptional profiling; Monocotyledones; Transcription; Induction; Nutrient recovery; Plant ecology; amino acids; Nitrogen; Cereal crop; nitrogen reduction; nitrogen limitation; Oryza sativa; Reduction; Gene; Gramineae; Aminoacid; Limitation; Angiospermae; Nodulin; Spermatophyta; Transgenic plant; nitrogen induction
• ISSN: 0140-7791; 1365-3040
• DOI: 10.1111/j.1365-3040.2009.02032.x

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.