Page 120 - Book of Abstracts

5 International Scientific Online Conference DOI: https://doi.org/10.15414/2021.9788055224015

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PARTICIPATION OF PHYTOHORMONES OF ETHYLENE AND BRASSINOSTEROIDS IN
CONTROL OF GRAVITROPIC REACTIONS OF PLANT LEAVES
Svetlana Sukhaveyeva, Alena Kabachevskaya
Institute of Biophysics and Cell Engineering National Academy of Sciences of Belarus, Minsk, Belarus;
E-mail.: suhoveevalmbc@mail.ru
Agricultural practices on Earth have evolved for a lot of years and the challenges may be
expected when they are adapted for space-based agriculture. One of the key variables in space
is gravity; therefore, it is important to understand the fundamental mechanisms, including
molecular biological ones, which underlie the plant's perception of gravity and adaptation to its
changes. Gravitropism is a universal property of all plants to perceive changes in gravity and
adapt to them through the directed growth of their organs. Different parts of a plant respond
differently to gravity: roots grow downwards (positive gravitropism); aerial parts of a plant
grow upwards (negative gravitropism). An important step involved in the gravitropic bending
is the redistribution of phytohormone auxin between different parts of gravistimulated organs.
However, the role of other growth phytohormones, including ethylene and brassinosteroids, in
the negative gravitropic response of plants has not been studied in detail, especially at the
transcriptional level.
This research aimed to evaluate the influence of gravistimulus on the expression of genes
associated with biosynthesis and signaling of brassinosteroids and ethylene such as ACS, EBF,
Curl, BRU, and some genes of SAUR-family in leaf cells as well as on sedimentation of
amyloplasts in petiole cells and curvature of stems. Gene sensitivity to gravistimulus was
determined in the apical leaves of tomato plants. For gravistimulus, the pots with experimental
plants were turned 90°C and exposed at different time intervals. The parts of experimental
groups were additionally treated with ethephon (the direct ethylene source) or brassinosteroid
(BS) epine. RT-PCR was used to quantify the level of relative expression of target genes.
Visualization of starch grains was carried out using light microscopy.
It was found that expression of SAURs, Curl, BRU1, and ACS was increased under
gravistimulation, while expression of EBF1 was moderately decreased at early stages of
response. Pretreatment of plants with a solution of BS increased the level of expression of most
of the studied genes, while ethephone reduced the increase in expression of some genes caused
by gravistimulation. It was also found, that gravistimulation caused the formation of the angle
of stem bending and sedimentation of amyloplasts during the exposure period of 15 min – 3 h,
BS accelerated and intensified the effects of gravistimulus, while the ethephone significantly
suppressed them.
Thus, the sensitivity of plant leaves to gravistimulation and the participation in the control
of the gravitropic response of such important regulators of plant growth and development as
BS and ethylene, in the perception of the gravistimulus were shown. It can be assumed that only
a part of genes was covered, and probably, gravistimulation will affect other genes expression
involved in plant metabolism.

Keywords: Lycopersicum esculentum, gravitropism, gene expression, ethylene, brassinosteroids.
Acknowledgments
We are grateful to the Institute of Physiology of the National Academy of Sciences of Belarus for help in
carrying out microscopic studies.

5 International Scientific Conference Agrobiodiversity for Improving the Nutrition, Health, Quality of Life and |119
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Spiritual Human Development
November 3 2021
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