CORRELATION OF IRON CONTENT, SPECTRAL FORMS OF CHLOROPHYLL AND CHLOROPHYLL-PROTEINS IN IRON-DEFICIENT CUCUMBER (CUCUMIS-SATIVUS)

Leaves and chloroplast suspensions of severely and slightly iron defic ient cucumber (Cucumis sativus L.) plants were characterized by low-te mperature fluorescence emission spectroscopy and Deriphat polyacrylami de gel electrophoresis. The emission spectra of the chloroplast suspen sions were resolved into Gaussian components and those changes induced by iron deficiency were related to the variations in the chlorophyll- protein pattern. The symptoms described with these methods were also c orrelated with the iron content of the leaves. It was concluded that t he lack of physiologically active iron caused a relative decrease of p hotosystem I (PSI) and light harvesting complex I (LHCI), together wit h the long wavelength fluorescence, especially the 740 nm Gaussian com ponent, and, to a much lesser extent, of the photosystem II (PSII) cor e complexes (relative increase of 685, 695 nm components). However, th e relative decrease in the amount of light harvesting complex II (LHCI I) was followed by a relative increase in its fluorescence band at 680 nm, showing that energy transfer from LHCII to core complex II (CCII) was partly disturbed. Thus iron deficiency affected the photosyntheti c apparatus in a complex way: it decreased the synthesis of chlorophyl ls (Chls) and influenced the expression and assembly of Chl-binding pr oteins.