ISSN:
1432-2048
Keywords:
Key words: Ammonium (assimilation)
;
Chlamydomonas
;
Glutamine synthetase (EC 6.3.1.2)
;
l-methionine-S-sulfoximine
;
Nitrogen assimilation
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract. A spontaneous double mutant of Chlamydomonas reinhardtii, designated ARF3, was resistant to L-methionine-S-sulfoximine (MSX), lacked chloroplastic glutamine synthetase (GS2) activity, and grew very poorly in all media tested. In segregants obtained after genetic crosses, the poor-growth phenotype was always linked to the lack of GS2 and to a diminished rate of consumption of ammonium, even under conditions where photorespiration was minimized. The ammonium permeases in mutant ARF3, however, were not altered. This indicates that, unlike in higher plants, GS2 contributes substantially to the primary assimilation of ammonia in this alga, and that its function cannot be replaced by the cytosolic glutamine synthetase. In genetic crosses, the MSX resistance and the lack of GS2 segregated independently, indicating that resistance was not due to an altered form of GS2.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s004250050502
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