บทคัดย่องานวิจัย

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Changes in glutamine synthetase in harvested asparagus spears: an opportunity for genetic modification?

Downs, C. G.; Borst, W. M.; Hurst, P. L.; King, G. A.; Stevenson, D. G.;

Acta Horticulturae Year: 1996 Issue: No. 415 Pages: 315-321 Ref: 28 ref.

1996

บทคัดย่อ

Changes in glutamine synthetase in harvested asparagus spears: an opportunity for genetic modification?

Glutamine synthetase (GS) [glutamate-ammonia ligase] content in asparagus spear tissues after harvest was investigated as a prelude to the genetic modification of the crop. Two forms of GS were identified in asparagus, associated with either the cytosol or the plastids. The 2 enzymes have distinct kinetic properties and contain polypeptides of different sizes. The abundance of the 2 GS forms changed as spears were held in the dark at 20 deg C for 5 d after harvest. The cytosolic enzyme activity declined immediately after harvest before rising rapidly 4-5 d after harvest. Ammonia also increased 4-5 d after harvest. Plastid GS enzyme activity declined and chlorophyll content decreased in the spear tips throughout the 5 d postharvest period. The possibility of overexpressing GS in genetically modified asparagus tissues in order to assimilate the ammonia that is produced after harvest is discussed and rejected.