Molecular Genetics of Nitrate Assimilation in Solanaceous Species
Nitrate can be used as the sole nitrogen source to sustain growth, in both microorganisms and higher plants. In plants, two successive enzymatic steps reduce nitrate to ammonium, generally in the leaves. First, nitrate is converted into nitrite in a two electron transfer reaction catalysed by nitrate reductase (NR, EC1. 6. 6. 1), a cytoplasmic enzyme. Nitrite is then translocated to the chloroplast, where it is reduced to ammonium by nitrite reductase (NiR, EC1. 7. 7.1) (for review see Wray 1988, Solomonson and Barber 1990). Ammonium is subsequently incorporated into the amino acid pool through glutamine and glutamate biosynthesis (Guerrero et al 1981).
KeywordsZinc Sugar Maize Carbohydrate Cysteine
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