THE INFLUENCE OF IRON-DEFICIENCY ON THE COMPOSITION OF CHLOROPHYLL-PROTEIN COMPLEXES AND THE ULTRASTRUCTURE OF PEA-CHLOROPLASTS

Using the method of gel-electrophoresis, all pigment-protein complexes were shown to exist in the chloroplasts of chlorotic leaves regardles s of their being light-green, yellow, or even yellowish-white. However , the quantity and proportion of individual complexes differed signifi cantly. As chlorosis progressed, the content of chlorophyll a/b light- harvesting complexes of PS II, including almost all the chlorophyll b, dropped most dramatically. In the light-green leaves of iron-deficien t plants, the quantity of intergranal thylakoids primarily decreased, and numerous osmiophilic globules emerged. The yellow leaves grown und er iron deficiency formed well-developed intergranal thylakoids and nu merous small grana. The grana formation, even in yellowish-white leave s, was evidently due to the higher stability of the photosystem reacti on centers, in particular those of PS II.The changes characteristic of iron-deficient plants occurred both in columnar and spongy parenchyma . In both tissues, the chloroplasts were approximately of the same siz e, though more oblong in columnar parenchyma. As chlorosis progressed, all chloroplasts became more rounded especially in spongy leaf tissue s.