title: Development and field performance of nitrogen use efficient rice lines for Africa.
abstract: Nitrogen (N) fertilizers are a major input cost in rice production, and its excess application leads to major environmental pollution. Development of rice varieties with improved nitrogen use efficiency (NUE) is essential for sustainable agriculture. Here, we report the results of field evaluations of marker-free transgenic NERICA4 (New Rice for Africa 4) rice lines overexpressing barley alanine amino transferase (HvAlaAT) under the control of a rice stress-inducible promoter (pOsAnt1). Field evaluations over three growing seasons and two rice growing ecologies (lowland and upland) revealed that grain yield of pOsAnt1:HvAlaAT transgenic events was significantly higher than sibling nulls and wild-type controls under different N application rates. Our field results clearly demonstrated that this genetic modification can significantly increase the dry biomass and grain yield compared to controls under limited N supply. Increased yield in transgenic events was correlated with increased tiller and panicle number in the field, and evidence of early establishment of a vigorous root system in hydroponic growth. Our results suggest that expression of the HvAlaAT gene can improve NUE in rice without causing undesirable growth phenotypes. The NUE technology described in this article has the potential to significantly reduce the need for N fertilizer and simultaneously improve food security, augment farm economics and mitigate greenhouse gas emissions from the rice ecosystem.
authors.affiliation: International Center for Tropical Agriculture (CIAT), Cali, Colombia.
authors.forename: Michael Gomez
authors.initials: MG
authors.lastname: Selvaraj
authors.affiliation: International Center for Tropical Agriculture (CIAT), Cali, Colombia.|Faculty of Agriculture Science, National University of Colombia, Palmira, Colombia.
authors.forename: Milton Orlando
authors.initials: MO
authors.lastname: Valencia
authors.affiliation: International Center for Tropical Agriculture (CIAT), Cali, Colombia.|Japan Society for the Promotion of Science Postdoctoral Fellow, Graduate School of Agricultural and Life Science, The University of Tokyo, Tokyo, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Ogawa
authors.affiliation: Arcadia Biosciences, Davis, CA, USA.
authors.forename: Yingzhi
authors.initials: Y
authors.lastname: Lu
authors.affiliation: Arcadia Biosciences, Davis, CA, USA.
authors.forename: Liying
authors.initials: L
authors.lastname: Wu
authors.affiliation: Arcadia Biosciences, Davis, CA, USA.
authors.forename: Christopher
authors.initials: C
authors.lastname: Downs
authors.affiliation: Arcadia Biosciences, Davis, CA, USA.
authors.forename: Wayne
authors.initials: W
authors.lastname: Skinner
authors.affiliation: Arcadia Biosciences, Davis, CA, USA.
authors.forename: Zhongjin
authors.initials: Z
authors.lastname: Lu
authors.affiliation: Arcadia Biosciences, Davis, CA, USA.
authors.forename: Jean C
authors.initials: JC
authors.lastname: Kridl
authors.affiliation: International Center for Tropical Agriculture (CIAT), Cali, Colombia.
authors.forename: Manabu
authors.initials: M
authors.lastname: Ishitani
authors.affiliation: Arcadia Biosciences, Davis, CA, USA.
authors.forename: Jos
authors.initials: J
authors.lastname: van Boxtel
mesh_terms: D000410:Alanine Transaminase / Q000235:genetics / Q000378:metabolism; D005838:Genotype; D009584:Nitrogen / Q000378:metabolism*; D012275:Oryza / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000201:enzymology / Q000235:genetics / Q000378:metabolism; D014170:Transformation, Genetic / Q000235:genetics
chemical_list: D000410:Alanine Transaminase; D009584:Nitrogen
keywords: alanine aminotransferase; confined field trial; grain yield; nitrogen use efficiency; transformation; transgenic rice