Effect of nicotianamine on iron uptake by the tomato mutant 'chloronerva'

In the tomato ( Lycopersicon esculentum L.) mutant 'chloronerva' the biosynthesis of nicotianamine, a derivative of the amino acid azetidine-2-carboxylic acid, is blocked. Application of nicotianamine to leaves of seedlings of the mutant reduced the abnormally high iron content of the plants to the level of the wild-type. In short-term experiments nicotianamine decreased the amount of iron removed from the nutrient medium by isolated roots of both wild-type and mutant. Addition of nicotianamine to the nutrient solution at 10⁻⁵ M inhibited the excessive iron uptake by the mutant and wild-type. This effect was more evident with ⁵⁹Fe-ethylenediamine-N, N'-bis-( o -hydroxyphenylacetic acid) than with ⁵⁹FeCl₃ as the iron source. It is concluded that nicotianamine plays a direct or indirect role as a regulator of iron uptake in plants.