title: Members of BTB Gene Family of Scaffold Proteins Suppress Nitrate Uptake and Nitrogen Use Efficiency.
abstract: Development of crops with improved nitrogen use efficiency (NUE) is essential for sustainable agriculture. However, achieving this goal has proven difficult since NUE is a complex trait encompassing physiological and developmental processes. We thought to tackle this problem by taking a systems biology approach to identify candidate target genes. First, we used a supervised machine-learning algorithm to predict a NUE gene network in Arabidopsis (Arabidopsis thaliana). Second, we identified BT2, a member of the Bric-a-Brac/Tramtrack/Broad gene family, as the most central and connected gene in the NUE network. Third, we experimentally tested BT2 for a role in NUE. We found NUE decreased in plants overexpressing BT2 gene compared to wild-type plants under limiting nitrate conditions. In addition, NUE increased compared to wild-type plants under low nitrate conditions in double mutant plants in bt2 and its closely related homolog bt1, indicating a functional redundancy of BT1 and BT2 for NUE. Expression of the nitrate transporter genes NRT2.1 and NRT2.4 increased in the bt1/bt2 double mutant compared to wild-type plants, with a concomitant 65% increase in nitrate uptake under low nitrate conditions. Similar to Arabidopsis, we found that mutation of the BT1/BT2 ortholog gene in rice (Oryza sativa) OsBT increased NUE by 20% compared to wild-type rice plants under low nitrogen conditions. These results indicate BT gene family members act as conserved negative regulators of nitrate uptake genes and NUE in plants and highlight them as prime targets for future strategies to improve NUE in crops.
authors.affiliation: Millennium Nucleus Center for Plant Systems and Synthetic Biology, FONDAP Center for Genome Regulation, Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile 8331010 (V.A., E.A.V., T.P., S.A., R.A.G.); and CIRAD, UMR AGAP, 34398 Montpellier cedex 5, France (D.M., E.G.).
authors.forename: Viviana
authors.initials: V
authors.lastname: Araus
authors.affiliation: Millennium Nucleus Center for Plant Systems and Synthetic Biology, FONDAP Center for Genome Regulation, Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile 8331010 (V.A., E.A.V., T.P., S.A., R.A.G.); and CIRAD, UMR AGAP, 34398 Montpellier cedex 5, France (D.M., E.G.).
authors.forename: Elena A
authors.initials: EA
authors.lastname: Vidal
authors.affiliation: Millennium Nucleus Center for Plant Systems and Synthetic Biology, FONDAP Center for Genome Regulation, Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile 8331010 (V.A., E.A.V., T.P., S.A., R.A.G.); and CIRAD, UMR AGAP, 34398 Montpellier cedex 5, France (D.M., E.G.).
authors.forename: Tomas
authors.identifier: 0000-0002-9820-4380
authors.initials: T
authors.lastname: Puelma
authors.affiliation: Millennium Nucleus Center for Plant Systems and Synthetic Biology, FONDAP Center for Genome Regulation, Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile 8331010 (V.A., E.A.V., T.P., S.A., R.A.G.); and CIRAD, UMR AGAP, 34398 Montpellier cedex 5, France (D.M., E.G.).
authors.forename: Simón
authors.initials: S
authors.lastname: Alamos
authors.affiliation: Millennium Nucleus Center for Plant Systems and Synthetic Biology, FONDAP Center for Genome Regulation, Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile 8331010 (V.A., E.A.V., T.P., S.A., R.A.G.); and CIRAD, UMR AGAP, 34398 Montpellier cedex 5, France (D.M., E.G.).
authors.forename: Delphine
authors.initials: D
authors.lastname: Mieulet
authors.affiliation: Millennium Nucleus Center for Plant Systems and Synthetic Biology, FONDAP Center for Genome Regulation, Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile 8331010 (V.A., E.A.V., T.P., S.A., R.A.G.); and CIRAD, UMR AGAP, 34398 Montpellier cedex 5, France (D.M., E.G.).
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Guiderdoni
authors.affiliation: Millennium Nucleus Center for Plant Systems and Synthetic Biology, FONDAP Center for Genome Regulation, Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile 8331010 (V.A., E.A.V., T.P., S.A., R.A.G.); and CIRAD, UMR AGAP, 34398 Montpellier cedex 5, France (D.M., E.G.) rgutierrez@bio.puc.cl.
authors.forename: Rodrigo A
authors.initials: RA
authors.lastname: Gutiérrez
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D018533:Biomass; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D053263:Gene Regulatory Networks; D026901:Membrane Transport Proteins / Q000378:metabolism; D005810:Multigene Family; D009566:Nitrates / Q000378:metabolism* / Q000494:pharmacology; D009584:Nitrogen / Q000378:metabolism*; D012275:Oryza / Q000235:genetics* / Q000378:metabolism*; D010940:Plant Proteins / Q000378:metabolism*
chemical_list: D026901:Membrane Transport Proteins; D009566:Nitrates; D010940:Plant Proteins; D009584:Nitrogen