DYNAMICS OF ULTRASTRUCTURE CHANGES IN SHEET PLATE FIBER FLAX WITH BRAKING TRANSPORT ASSIMILATE BY NITRATE-ANION
F. A. Abdrakhimov, S. N. Batasheva, G. G. Bakirova, V. I. Chikov 1
Kazan Institute of Biochemistry and Biophysics KNC RAS;
1 e-mail: chikov@kzn.ru
Changes in leaf mesophyll cell ultrastructure under nitrate feeding into the apoplast of common flax (Linum usitatissimum L.) in the form of 50 mM
KNO3 solution were studied. In 30 min after the beginning of nitrate feeding through the transpiration water stream, swelling of mitochondrial and
microbodies, clarification of their matrices, and curling of dictyosome discs into annular structures were observed. These events characterized symplastic domain
formed by mesophyll, bundle sheath and phloem parenchyma cells, and were not found in companion cell-sieve element complex. Simultaneously, formation of large
central vacuoles in companion cells was noted. Restoration of organelle structures in assimilating cells and phloem parenchyma in 1-2 h after treatment was
accompanied by enhancement of morphological changes in phloem elements and companion cells and signs of plasmolysis in the mesophyll cells. It was
supposed that the two-phase character of changes in leaf orga-nelle ultrastructure and photosynthesis might reflect duality of leaf cell response to nitrate ion.
The rapid alterations of the structure can be coupled with direct influence of the anion on cell metabolism and(or) with signal-regulatory functions of oxidized nitrogen
forms, while the slower ones reflect the result of suppression of photoassimilate export from leaves by the anion.
Key words: ultrastructure, photosynthesis, transport of assimilates, minor vein, nitrates
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