Ammonia assimilation leaves

As stated previously, the rate of ammonia production in the glycine serine conversion reaction during photorespiration in a C3 plant leaf is approximately 10 times the normal rate of nitrate assimilation (Keys et al., 1978). There is therefore a major requirement for the plant to reassimilate the ammonia as rapidly as possible. Experiments with inhibitors of and mutants lacking the key enzymes have clearly shown that plants die very rapidly if ammonia assimilation is blocked (Lea and Ridley, 1989 Blackwell et al., 1988b). 

Fig. 2. The assimilation of ammonia by isolated spinach leaf cells in light and dark, (a) Time course of N incorporation from [ N]H< into the amide N of glutamine (O) the amino N of glutamate ( ) and the amino N of glutamine ( ). (b) Incorporation of N from [ N]H4 into aspartate, glutamate and glutamine in the light for I min and thereafter in either light (open symbols) or dark (solid symbols). (Redrawn from Ito et al., 1978.)...

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