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Two genes encoding distinct cytosolic glutamine synthetases are closely linked in the pine genome
Author(s) -
Ávila Sáez Concepción,
Muñoz-Chapuli Ramón,
Plomion Christophe,
Frigerio Jean-Marc,
Cánovas Francisco M.
Publication year - 2000
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(00)01796-8
Subject(s) - gymnosperm , gene , biology , complementary dna , isozyme , glutamine synthetase , genetics , cytosol , genome , phylogenetic tree , gene duplication , gene family , gene isoform , biochemistry , glutamine , microbiology and biotechnology , enzyme , botany , amino acid
The major isoenzyme of glutamine synthetase found in leaves of angiosperms is the chloroplastic form. However, pine seedlings contain two cytosolic glutamine synthetases in green cotyledons: GS1a, the predominant isoform, and GS1b, a minor enzyme whose relative amount is increased following phosphinotricin treatment. We have cloned a GS1b cDNA, and comparison with the previously reported GS1a cDNA sequence indicated that they correspond to separate cytosolic GS genes encoding distinct protein products. Phylogenetic analysis showed that the newly reported sequence is closer to cytosolic angiosperm GS than to GS1a, suggesting therefore that GS1a could be a divergent gymnospermous GS1 gene. Gene mapping using a F2 family of maritime pine showed co‐localization of both GS genes on group 2 of the genetic linkage map. This result supports the proposed origin of different members of the GS1 family by adjacent gene duplication. The implications for gymnosperm genome organization are discussed.