COULD IRON NUTRITION STATUS BE EVALUATED THROUGH PHOTOSYNTHETIC PIGMENT CHANGES

Iron deficiency decreases the amount of photosynthetic pigments in higher plants, and also results in characteristic changes in the relative photosynthetic pigment composition. Iron deficient plants exhibit a relative increase in xanthophylls, largely attributable to pigments within the xanthophyll cycle, violaxanthin, antheraxanthin, and zeaxanthin. Furthermore, the xanthophyll cycle functions in Fe-deficient plants, but not in other yellow, carotenoid enriched-materials, such as etiolated or senescing leaves. When Fe-deficient leaves are illuminated, part of the violaxanthin is converted into antheraxanthin and zeaxanthin. When Fe-deficient leaves are placed in the dark, the cycle reverts back to violaxanthin. In this paper we present further data on this cycle and discuss the possible relevance of pigment changes as an alternative mechanism for the dissipation of excess energy. The possibility of using characteristic pigment changes as a tool for monitoring Fe status in higher plants is discussed.