02318naa a2200265 a 450000100080000000500110000800800410001910000230006024501280008326000090021152015360022065000140175665000210177065300330179165300080182465300080183265300390184070000200187970000200189970000140191970000160193370000190194970000190196877300650198716250652006-12-08       2005    bl ---       0--  u    #d1 aNOGUEIRA, E. de M.  aCharacterization of glutamine synthetase genes in sugarcane genotypes with different rates of biological nitrogen fixation.  c2005  aDifferent Brazilian sugarcane genotypes have different rates of Biological Nitrogen Fixation (BNF) and higher BNF correlates with their ability to grow with low nitrogen input. As a first step to investigate the role of sugarcane nitrogen metabolism in the good performance of Brazilian genotypes to grow in nitrogen poor soil we identified and characterized members of glutamine synthetase (GS) family in sugarcane. Five genes were identified, encoding for cytosolic (scGSl:a, scGS1.b and scGS1.c), plastidic (scGS2) and dodecameric (scGSI) GS.These genes are. differentially expressed in sugarcane organs and scGS1.a is the most expressed one. scGS1.b expression increases during shoot development, reaching high levels in mature leaves of SP70-1143 genotype (high BNF) and moderate levels in Chunee genotype( low BNF). Treatment with ammonia increased the expression of scGSl.b only in SP70-1143. ln addition, withdrawal of ammonia enhanced expression of scGS l.a and scGS 1.b olly in sp70- 1143. The data suggests that scGS l.a and scGS l.b can be important for nitrogen assimilation in sugarcane, including not only lhe nitrogen provided by BNF, but also snpplied by soil and by remobilization. Their differential expression in SP70-1 143 and Chunee genotypes could explain, at least to some extent, variations in the performance of these genotypes to grow with low nitrogen input.  2004 Elsevier Ireland Ltd. All rights reserved.  Keywordrs: Biological nitrogen fixation; Glutamine synthetase; Nitrogen metabolism; Sugarcane.  asugarcane  aCana de Açúcar  aBiological nitrogen fixation  aBNF  aFBN  aFixação biológica de nitrogenio1 aOLIVARES, F. L.1 aJAPIASSU, J. C.1 aVILAR, C.1 aVINAGRE, F.1 aBALDANI, J. I.1 aHEMERLY, A. S.  tPlant Science, Irelandgv. 169, n. 5, p. 819-832, nov. 2005.