EFFECT OF MALONATE ON THE STRUCTURAL AND FUNCTIONAL Ñ HANGES OF WHEAT TRITICUM
AESTIVUM L. ROOT CELLS
E. N. Bufetov,1 O. O. Polygalova, A. A. Ponomareva
Institute of Biochemistry and Biophysics, Kazan' Scientific Centre RAS, Kazan', Russia;
1 e-mail: ponomareva@mail.knc.ru
A study was made of respiration, output of K+ and ultrastracture of wheat root cells treated for 6 h with malonic acid (MA) (15 mM), an inhibitor
of succinate dehydrogenase. After a 1 h treatment, on the background of a decrease in respiration and output of K+ an increased number of lumens of smooth
endoplasmic reticulum was observed. These changes may be the result of lipid biosynthesis. Within first hours of treatment with MA, the mitochondrial matrix v as becoming
more brightened, and after 3 h all organelles became transparent. Moreover, mitochondria increased in size and almost lacked cristae. After 4 h mitochondria assumed their
normal sizes due, presumably, to a competitive action of malonate. After 5 h the matrix was brightened again, mitochondria augmented in size, several organelles acquired torus
shapes, and their outer area was eventually increased. We found contacts of endoplasmic reticulum lumens with mitochondria, which may suggest the synthesis of an enzyme,
able to transform to malonate. After a 6 h exposure of MA, we observed the increase of respiration, re-entry of K+ and normal ultrastructure of mitochondria.
Based on our experiments, we conclude that adaptation of root cells may be a result î external NADPH-dehydrogenase activity and MA detoxification.
Key words: wheat roots, malonate, respiration, mitochondria
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