Hoque Mohammad S, Masle Josette, Udvardi Michael K, Ryan Peter R, Upadhyaya Narayana M
Research School of Biological Sciences, The Australian National University, Canberra, ACT 2000, Australia.
Department of Biochemistry and Molecular Biology, The Australian National University, Canberra, ACT 2000, Australia. Current address: Max Planck Institute for Molecular Plant Physiology, Am Mühlenberg 1, 14476 Potsdam-Golm, Germany.
Funct Plant Biol. 2006 Mar;33(2):153-163. doi: 10.1071/FP05165.
A transgenic approach was undertaken to investigate the role of a rice ammonium transporter (OsAMT1-1) in ammonium uptake and consequent ammonium assimilation under different nitrogen regimes. Transgenic lines overexpressing OsAMT1-1 were produced by Agrobacterium-mediated transformation of two rice cultivars, Taipei 309 and Jarrah, with an OsAMT1-1 cDNA gene construct driven by the maize ubiquitin promoter. Transcript levels of OsAMT1-1 in both Taipei 309 and Jarrah transgenic lines correlated positively with transgene copy number. Shoot and root biomass of some transgenic lines decreased during seedling and early vegetative stage compared to the wild type, especially when grown under high (2 mm) ammonium nutrition. Transgenic plants, particularly those of cv. Jarrah recovered in the mid-vegetative stage under high ammonium nutrition. Roots of the transgenic plants showed increased ammonium uptake and ammonium content. We conclude that the decreased biomass of the transgenic lines at early stages of growth might be caused by the accumulation of ammonium in the roots owing to the inability of ammonium assimilation to match the greater ammonium uptake.
采用转基因方法研究水稻铵转运蛋白（OsAMT1-1）在不同氮素供应条件下对铵吸收及后续铵同化作用的影响。通过农杆菌介导的转化方法，利用玉米泛素启动子驱动的OsAMT1-1 cDNA基因构建体，将两个水稻品种台北309和Jarrah转化为过表达OsAMT1-1的转基因株系。台北309和Jarrah转基因株系中OsAMT1-1的转录水平与转基因拷贝数呈正相关。与野生型相比，部分转基因株系在幼苗期和营养生长早期的地上部和根部生物量下降，尤其是在高铵（2 mM）营养条件下生长时。转基因植株，特别是Jarrah品种的植株，在营养生长中期在高铵营养条件下恢复生长。转基因植株的根系表现出铵吸收增加和铵含量升高。我们得出结论，转基因株系在生长早期生物量下降可能是由于铵同化能力无法匹配更大的铵吸收量，导致铵在根部积累所致。
