Аннотация:The overall survival of a plant depends on the development, growth, and functioning of
the roots. Root development and growth are not only genetically programmed but are constantly
influenced by environmental factors, with the roots adapting to such changes. The peptide AEDL
(alanine–glutamine acid–asparagine acid–leucine) at a concentration of 107 M had an elongating
effect on the root cells of Nicotiana tabacum seedlings. The action of this peptide at such a low
concentration is similar to that of peptide phytohormones. In the presence of 150 mM NaCl, a strong
distortion in the development and architecture of the tobacco roots was observed. However, the
combined presence of AEDL and NaCl resulted in normal root development. In the presence of
AEDL, reactive oxygen species (ROS) were detected in the elongation and root hair zones of the
roots. The ROS marker fluorescence intensity in plant cells grown with AEDL was much lower than
that of plant cells grown without the peptide. Thus, AEDL protected the root tissue from damage
by oxidative stress caused by the toxic effects of NaCl. Localization and accumulation of AEDL
at the root were tissue-specific. Fluorescence microscopy showed that FITC-AEDL predominantly
localized in the zones of elongation and root hairs, with insignificant localization in the meristem zone.
AEDL induced a change in the structural organization of chromatin. Structural changes in chromatin
caused significant changes in the expression of numerous genes associated with the development and
differentiation of the root system. In the roots of tobacco seedlings grown in the presence of AEDL,
the expression of WOX family genes decreased, and differentiation of stem cells increased, which
led to root elongation. However, in the presence of NaCl, elongation of the tobacco root occurred
via a different mechanism involving genes of the expansin family that weaken the cell wall in the
elongation zone. Root elongation of plants is of fundamental importance in biology and is especially
relevant to crop production as it can affect crop yields.