Аннотация:Humic acids (HA) are natural organic compounds that are important components of organic matter.
The accumulation, distribution, and fate of tritium-labeled HA prepared from coal were analyzed
using wheat (Triticum aestivum L.) seedlings. There was a period of rapid accumulation of
HA followed by a slower one in the period from 1 to 24 h. There was a significant decrease in HA
accumulation at low temperature, indicating that the slower rate of HA accumulation represented
a membrane-mediated process. HA distribution in plant tissues was analyzed using autoradiography.
In all cases, HA concentration was considerably higher in the roots than in the shoots. Detailed
examination of autoradiograms showed that there was preferential accumulation of HA in
the apices of roots and shoots of wheat seedlings. Lipid fractions were extracted from seedlings
and analyzed with thin layer chromatography and gas chromatography–mass spectrometry.
These analyses revealed that labeled HA were present in the neutral lipid fraction consisting
mainly of alkanes and alkenes, which are usually found in plant waxes, associated with the cuticle
and suberized tissues. Based on these data, it is suggested that HA-derived hydrocarbons
may be used in wax biosynthesis. This role could explain the mitigating activity of humic substances
under stress conditions.