LEAF RESPONSES TO FE DEFICIENCY - A REVIEW

Iron deficiency induces changes in the structure and function of the whole photosynthetic apparatus of higher plants. The iron deficiency-induced decrease in pigments seems to arise from the absolute requirement for iron in the formation of thylakoid membrane. Modifications found in the thylakoid composition of iron deficient leaves include changes in the photosystem II to photosystem I stoichiometry, in the xanthophylls to chlorophylls ratio and in their lipid composition. Some of these changes may result in some protection towards photoinhibition. Changes in other leaf components, such as leaf lipids and iron fractions are discussed. Changes in parameters evaluating leaf functions, including gas exchange, water status and chlorophyll fluorescence are also discussed. New issues on iron deficiency, such as the possible misuse of membrane fractions, the rapid adaptation changes which are found to occur during the day in the iron deficient leaves in response to light conditions, and the comparison of iron deficient plants grown in controlled environments with iron deficient plants grown in the field are introduced.