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Characterization of transgenic poplar with ectopic expression of pine cytosolic glutamine synthetase under conditions of varying nitrogen availability
Author(s) -
Man Huimin,
Boriel Randall,
ElKhatib Rami,
Kirby Edward G.
Publication year - 2005
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.2005.01461.x
Subject(s) - glutamine synthetase , nitrogen assimilation , glutamine , transgene , ectopic expression , ammonium , biology , amino acid , genetically modified crops , cytosol , biochemistry , nitrogen , salicaceae , botany , horticulture , chemistry , enzyme , woody plant , gene , organic chemistry
Summary• The present study addresses the hypothesis that enhanced expression of glutamine synthetase (GS) in transgenic poplar, characterized by the ectopic expression of pine cytosolic GS, results in an enhanced efficiency of nitrogen (N) assimilation and enhanced growth. • Transgenic and control poplar were supplied with low and high N levels and the role of ectopic expression of the pine GS in growth and N assimilation was assessed by using amino acid analysis, 15 N enrichment, biochemical analyses, and growth measurements. • While leaves of transgenic poplar contained 85% less ( P < 0.01) free ammonium than leaves of nontransgenic control plants, leaves of transgenics showed increases in the levels of free glutamine and total free amino acids. Transgenic poplar lines also displayed significant increases in growth parameters when compared with controls grown under both low (0.3 m m ) and high (10 m m ) nitrate conditions. Furthermore, 15 N‐enrichment experiments showed that 27% more ( P < 0.05) 15 N was incorporated into structural compounds in transgenic lines than in nontransgenic controls. • Using the methods described here, we present direct evidence for increased N assimilation efficiency and growth in GS transgenic lines.