EXOGENOUS ZEATIN ACCUMULATION IN WHEAT ROOT CELLS SHOWS ITS ROLE
IN REGULATION OF CYTOKININ TRANSPORT
G. R. Akhiyarova, T. N. Arkhipova
Institute of Biology RAS, Ufa;
e-mail: akhiyarova@rambler.ru
Here we have shown that 24 hours after addition of zeatin to the nutrient solution the cytokinin content in
xylem sap of wheat plants appears to be about 10 times lower that in the nutrient solution. Cytokinins accumulated
mostly in roots and not in shoots of treated plants. These data demonstrate the existence of some barrier on
cytokinin pathway from the nutrient solution to the plant shoot. With the help of Sudan III an increase in lignin
and suberin deposition in the endodermis could be detected, being stronger with the increase in the distance
from the root tip. The increase in deposition of suberin and lignin coincided with the decrease in cytokinin immunolabeling
in root cells revealed with the help of monoclonal cytokinin antibodies and the second gold-labelled
antibodies. Simultaneously exogenous cytokinins accumulated in root stele cells showing that the Casparian
band was not only barrier on cytokinin pathway to plant shoot. It is concluded that high cytokinin immunolabeling
in the stele parenchyma cells around the stele vessels demonstrated accumulation of cytokinins by these
cells, which could be important in regulation of cytokinin loading to the xylem vessels during there transport to
the shoot. The role of cytokinin transporters is discussed.
Key words: Triticum durum Desf., zeatin, immunolocalization, cortex, endodermis, pericycle, stele
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