EFFECTS OF THE OVEREXPRESSION OF A SOYBEAN CYTOSOLIC GLUTAMINE SYNTHETASE GENE (GS15) LINKED TO ORGAN-SPECIFIC PROMOTERS ON GROWTH AND NITROGEN ACCUMULATION OF PEA PLANTS

摘要

Glutamine synthetase (GS; EC 6.3.1.2) is a critical enzyme in the assimilation of ammonia into amino acids in higher plants and enhancement of its activity in plants may increase nitrogen utilization efficiency (Miflin and Habash, 2002). Overexpression of the cytosolic GS gene (GS1) has lead to increases in biomass and N accumulation (Habash et al., 2001; Oliveira et al., 2002). However, other studies indicate that over-expression of GS1 leads to nil or even negative responses in plant function and growth. For example, overexpression of a soybean GS1 linked to a nodule specific promoter (LBC_3) in Lotus japonicus lead to increases in GS activity, but no effects on nodule biomass or N_2 fixation (Limami et al., 1999). Over-expression of a rolD-GSl gene in the same species actually led to decreases in root biomass (Limami et al., 1999).