Functional characterisation of OsAMT1.1 overexpression lines of rice, Oryza sativa
Anshuman Kumar A B , Brent N. Kaiser A C , M. Yaeesh Siddiqi A and Anthony D. M. Glass A DA Department of Botany, University of British Columbia, 6270 University Blvd, Vancouver, Canada V6T 1Z4.
B Current address: Department of Biology, Colorado State University, Fort Collins, CO 80523, USA.
C Current address: School of Agriculture and Wine, University of Adelaide, PMB 1 Glen Osmond, SA 5064, Australia.
D Corresponding author. Email: aglass@interchange.ubc.ca
Functional Plant Biology 33(4) 339-346 https://doi.org/10.1071/FP05268
Submitted: 31 October 2005 Accepted: 9 February 2006 Published: 3 April 2006
Abstract
In rice (Oryza sativa L.) OsAMT1.1 is the most active and / or most N-responsive gene responsible for high-affinity NH4+ transport (HATS) activity. We measured 13NH4+ influx and plant biomass in transgenic overexpression lines and two wild type cultivars of rice, Jarrah and Taipei, with one or more copies of OsAMT1.1. 13NH4+ influx was higher for the overexpression lines of Jarrah line when grown at 10 µm external NH4+ concentration, but not for the overexpression lines of Taipei. For seedlings grown at 2 mm external NH4+ concentration Jarrah lines 77-1 and 75-4 showed an increased influx; however, two overexpression lines of Taipei showed reduced influx rates. The biomasses of the transgenic lines grown at low and high external NH4+ concentrations were either reduced or showed no statistically significant differences compared with wild type lines. While 13NH4+ influx into roots of Jarrah line 75-4 grown at 10 µm external NH4+ concentration was significantly higher than in wild type, measurements of 13NH efflux revealed no differences, and thus net uptake of NH4+ was higher in this overexpression line.
Keywords: ammonium transporter, AMT, efflux, high-affinity transport system, influx, OsAMT1.1, over-expression.
Acknowledgments
Authors gratefully acknowledge Dr Jossette Masle of Research School of Biological Sciences, Australian National University, for providing the seeds of overexpression lines of rice. The research work was partially supported by NSERC grants to ADM Glass. We also acknowledge the supply of 13N by TRIUMF cyclotron facility.
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