STRUCTURAL-FUNCTIONAL ORGANIZATION OF CHLOROPLASTS IN LEAVES OF PISUM SATIVUM L. UNDER CONDITIONS OF ROOT HYPOXIA
AND IRON DEFICIENCY
V. G. Ladygin, G. A. Semenova 1
Institute of Basic Biological Problems RAS, and 1Institute of Theoretical and Experimental Biophysics RAS, Pushchino, Moscow region, Russia;
e-mail: ladygin@issp.serpukhov.su
A combined effect of iron deficiency and root hypoxia on the biochemical composition, functional activity and structure of chloroplasts in pea leaves have been
studied. Both factors are shown to affect the accumulation of chlorophyll causing leaf chlorosis. At iron deficiency chlorosis occurs from the top of plant leaves. At root hypoxia
chlorosis starts from the lower strata. At a combined action of both factors the destructive effects are summarized. It was established that light-harvesting complexes of
photosystems were reduced stronger at iron deficiency, while complexes of reaction centers of photosystem I and photosystem II are lessened at root hypoxia. Nevertheless,
even at a combined effect of both factors yellow leaves preserved small amounts of any pigment-protein complexes and their functional activities. The ultrastructure of chloroplasts
during leaf chlorosis was gradually reduced. At first, intergranal sites of thylakoids and then granal ones were destroyed, that was typical of iron deficiency. However, even yellow
and almost white leaves kept small thylakoids, capable of forming stacking and small grana made of 2-3 thylakoids. It has been concluded that the destructive effects are
summarized due to different kinds of action of iron deficiency and root hypoxia on the structure and functioning of leaves at their combined action.
Key words: Pisum sativum L., root hypoxia, iron deficiency, photosystems, chloroplast ultrastructure, photosynthesis
