Effects of exogenous bacterial quorum sensing signal molecule (messenger) N-hexanoyl- L-homoserine lactone (C₆-HSL) on morpho logical and physiological responses of winter wheat under simulated acid rain
This research aims to investigate the influence of foliar treatment by bacterial quorum sensing signal molecule/messenger N-hexanoyl-L-homoserine lactone (C₆-HSL, 100 ng/ml) on morphological and functional characteristics of Triticum aestivum L. cv. Yatran 60 leaves under simulated acid rain (SAR)...
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| Цитувати: | Effects of exogenous bacterial quorum sensing signal molecule (messenger) N-hexanoyl- L-homoserine lactone (C₆-HSL) on morpho logical and physiological responses of winter wheat under simulated acid rain / I.V. Kosakivska, L.M. Babenko, К.О. Romanenko, O.A. Futorna // Доповіді Національної академії наук України. — 2020. — № 8. — С. 92-100. — Бібліогр.: 15 назв. — англ. |
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Kosakivska, I.V. Babenko, L.M. Romanenko, К.О. Futorna, O.A. 2020-11-21T14:48:27Z 2020-11-21T14:48:27Z 2020 Effects of exogenous bacterial quorum sensing signal molecule (messenger) N-hexanoyl- L-homoserine lactone (C₆-HSL) on morpho logical and physiological responses of winter wheat under simulated acid rain / I.V. Kosakivska, L.M. Babenko, К.О. Romanenko, O.A. Futorna // Доповіді Національної академії наук України. — 2020. — № 8. — С. 92-100. — Бібліогр.: 15 назв. — англ. 1025-6415 DOI: doi.org/10.15407/dopovidi2020.08.092 https://nasplib.isofts.kiev.ua/handle/123456789/173104 581.143.6 This research aims to investigate the influence of foliar treatment by bacterial quorum sensing signal molecule/messenger N-hexanoyl-L-homoserine lactone (C₆-HSL, 100 ng/ml) on morphological and functional characteristics of Triticum aestivum L. cv. Yatran 60 leaves under simulated acid rain (SAR). Acid rain is one of the most dangerous abiotic stressor, which negatively affects the plant growth and development. It changes the permeability and photochemical activity of membranes, leads to the disruption of a chloroplast ultrastructure, stomata system functioning, reduces CO₂ photofixation. Using the scanning electron microscopy, we identified that, after the foliar treatment by C₆-HSL, the thickness of the leaf cell wall along with the cuticle layer in 20-day-old plants increased by 15 %. Under SAR condition, the plants have suffered the disruption of the cuticular wax layer and uneven wax plates on the epidermis surface, whereas the plants treated with C₆-HSL showed only a partial cracking of the cuticular wax layer, slight disruption of wax plates, and formation of a wax shell. The C₆-HSL-treated plants showed the normal functioning of stomata guard cells and the stabilization in the content of photosynthetic pigments. The protective effect of the foliar treatment with C₆-HSL solution in winter wheat plants under SAR and perspective of its using for the induction of stress resistance has been discussed. Досліджено вплив фоліарної обробки водним розчином сигнальної молекули-медіатора бактеріального походження N-гексаноїл-L-гомосеринлактону (C₆-ГГЛ, 100 нг/мл) на структурно-функціональні характеристики Triticum aestivum L. сорту Ятрань 60 за умов дії модельованого кислотного дощу (МКД). Кислотні дощі належать до найнебезпечніших абіотичних стресорів, які негативно впливають на ріст і розвиток рослин. Наслідком кислотного дощу є зміна проникності мембран, порушення в ультраструктурі хлоропластів, функціонуванні продихової системи, зниження фотофіксації CO₂ і фотохімічної активності. Методом сканувальної електронної мікроскопії встановлено, що товщина клітинної стінки разом із шаром кутикули у 20-добових рослин, оброблених C₆-ГГЛ, збільшилась на 15 %. Під дією МКД у рослин руйнувався шар кутикулярного воску і нерівнокраї воскові пластинки на поверхні епідермісу, тоді як у рослин, що були оброблені C₆-ГГЛ, спостерігалося лише часткове розтріскування шару кутикулярного воску, незначне руйнування воскових пластинок і формування воскових кірок. У рослин, оброблених C₆-ГГЛ, зафіксоване нормальне функціонування замикаючих клітин продихів і стабілізація у вмісті фотосинтетичних пігментів. Обговорюється захисний ефект фоліарної обробки розчином C₆-ГГЛ рослин озимої пшениці в умовах МКД та перспективи використання цієї речовини для підвищення стресостійкості. The paper is based on the results of the project № 0120U102936 “Development of innovative biotechnology for increasing the stability and productivity of cereals based on a complex of signaling molecules of plant and bacterial origin for environmental protection and restoration” (2020—2024) funded by the National Academy of Sciences of Ukraine. en Видавничий дім "Академперіодика" НАН України Доповіді НАН України Екологія Effects of exogenous bacterial quorum sensing signal molecule (messenger) N-hexanoyl- L-homoserine lactone (C₆-HSL) on morpho logical and physiological responses of winter wheat under simulated acid rain Вплив екзогенної обробки водним розчином сигнальної молекули-медіатора бактеріального походження n-гексаноїл-l-гомосеринлактону (C₆-ГГЛ) на морфологічні та фізіологічні реакції озимої пшениці за умов дії модельованого кислотного дощу Article published earlier |
| institution |
Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| collection |
DSpace DC |
| title |
Effects of exogenous bacterial quorum sensing signal molecule (messenger) N-hexanoyl- L-homoserine lactone (C₆-HSL) on morpho logical and physiological responses of winter wheat under simulated acid rain |
| spellingShingle |
Effects of exogenous bacterial quorum sensing signal molecule (messenger) N-hexanoyl- L-homoserine lactone (C₆-HSL) on morpho logical and physiological responses of winter wheat under simulated acid rain Kosakivska, I.V. Babenko, L.M. Romanenko, К.О. Futorna, O.A. Екологія |
| title_short |
Effects of exogenous bacterial quorum sensing signal molecule (messenger) N-hexanoyl- L-homoserine lactone (C₆-HSL) on morpho logical and physiological responses of winter wheat under simulated acid rain |
| title_full |
Effects of exogenous bacterial quorum sensing signal molecule (messenger) N-hexanoyl- L-homoserine lactone (C₆-HSL) on morpho logical and physiological responses of winter wheat under simulated acid rain |
| title_fullStr |
Effects of exogenous bacterial quorum sensing signal molecule (messenger) N-hexanoyl- L-homoserine lactone (C₆-HSL) on morpho logical and physiological responses of winter wheat under simulated acid rain |
| title_full_unstemmed |
Effects of exogenous bacterial quorum sensing signal molecule (messenger) N-hexanoyl- L-homoserine lactone (C₆-HSL) on morpho logical and physiological responses of winter wheat under simulated acid rain |
| title_sort |
effects of exogenous bacterial quorum sensing signal molecule (messenger) n-hexanoyl- l-homoserine lactone (c₆-hsl) on morpho logical and physiological responses of winter wheat under simulated acid rain |
| author |
Kosakivska, I.V. Babenko, L.M. Romanenko, К.О. Futorna, O.A. |
| author_facet |
Kosakivska, I.V. Babenko, L.M. Romanenko, К.О. Futorna, O.A. |
| topic |
Екологія |
| topic_facet |
Екологія |
| publishDate |
2020 |
| language |
English |
| container_title |
Доповіді НАН України |
| publisher |
Видавничий дім "Академперіодика" НАН України |
| format |
Article |
| title_alt |
Вплив екзогенної обробки водним розчином сигнальної молекули-медіатора бактеріального походження n-гексаноїл-l-гомосеринлактону (C₆-ГГЛ) на морфологічні та фізіологічні реакції озимої пшениці за умов дії модельованого кислотного дощу |
| description |
This research aims to investigate the influence of foliar treatment by bacterial quorum sensing signal molecule/messenger
N-hexanoyl-L-homoserine lactone (C₆-HSL, 100 ng/ml) on morphological and functional characteristics of
Triticum aestivum L. cv. Yatran 60 leaves under simulated acid rain (SAR). Acid rain is one of the most dangerous
abiotic stressor, which negatively affects the plant growth and development. It changes the permeability and photochemical
activity of membranes, leads to the disruption of a chloroplast ultrastructure, stomata system functioning,
reduces CO₂ photofixation. Using the scanning electron microscopy, we identified that, after the foliar treatment
by C₆-HSL, the thickness of the leaf cell wall along with the cuticle layer in 20-day-old plants increased by 15 %.
Under SAR condition, the plants have suffered the disruption of the cuticular wax layer and uneven wax plates on
the epidermis surface, whereas the plants treated with C₆-HSL showed only a partial cracking of the cuticular wax
layer, slight disruption of wax plates, and formation of a wax shell. The C₆-HSL-treated plants showed the normal
functioning of stomata guard cells and the stabilization in the content of photosynthetic pigments. The protective
effect of the foliar treatment with C₆-HSL solution in winter wheat plants under SAR and perspective of its using
for the induction of stress resistance has been discussed.
Досліджено вплив фоліарної обробки водним розчином сигнальної молекули-медіатора бактеріального
походження N-гексаноїл-L-гомосеринлактону (C₆-ГГЛ, 100 нг/мл) на структурно-функціональні характеристики Triticum aestivum L. сорту Ятрань 60 за умов дії модельованого кислотного дощу (МКД). Кислотні дощі належать до найнебезпечніших абіотичних стресорів, які негативно впливають на ріст і розвиток рослин. Наслідком кислотного дощу є зміна проникності мембран, порушення в ультраструктурі хлоропластів, функціонуванні продихової системи, зниження фотофіксації CO₂ і фотохімічної активності.
Методом сканувальної електронної мікроскопії встановлено, що товщина клітинної стінки разом із шаром
кутикули у 20-добових рослин, оброблених C₆-ГГЛ, збільшилась на 15 %. Під дією МКД у рослин руйнувався шар кутикулярного воску і нерівнокраї воскові пластинки на поверхні епідермісу, тоді як у рослин,
що були оброблені C₆-ГГЛ, спостерігалося лише часткове розтріскування шару кутикулярного воску, незначне руйнування воскових пластинок і формування воскових кірок. У рослин, оброблених C₆-ГГЛ, зафіксоване нормальне функціонування замикаючих клітин продихів і стабілізація у вмісті фотосинтетичних пігментів. Обговорюється захисний ефект фоліарної обробки розчином C₆-ГГЛ рослин озимої пшениці в умовах МКД та перспективи використання цієї речовини для підвищення стресостійкості.
|
| issn |
1025-6415 |
| url |
https://nasplib.isofts.kiev.ua/handle/123456789/173104 |
| citation_txt |
Effects of exogenous bacterial quorum sensing signal molecule (messenger) N-hexanoyl- L-homoserine lactone (C₆-HSL) on morpho logical and physiological responses of winter wheat under simulated acid rain / I.V. Kosakivska, L.M. Babenko, К.О. Romanenko, O.A. Futorna // Доповіді Національної академії наук України. — 2020. — № 8. — С. 92-100. — Бібліогр.: 15 назв. — англ. |
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92
ОПОВІДІ
НАЦІОНАЛЬНОЇ
АКАДЕМІЇ НАУК
УКРАЇНИ
ISSN 1025-6415. Dopov. Nac. akad. nauk Ukr. 2020. № 8: 92—100
Ц и т у в а н н я: Kosakivska I.V., Babenko L.M., Romanenko K.О., Futorna O.A. Effects of exogenous bacterial
quorum sensing signal molecule (messenger) N-hexanoyl-L-homoserine lactone (C6-HSL) on morphological
and physiological responses of winter wheat under simulated acid rain. Допов. Нац. акад. наук Укр. 2020. № 8.
С. 92—100. https://doi.org/10.15407/dopovidi2020.07.092
Acid rain is one of the most dangerous abiotic stressors that adversely affects the growth and de-
velopment of a plant, as plants and soil are their main sorbents. Acid rain is typical of countries
with a high level of urbanization [1]. The acidity (pH) of pure rainwater is 6.6, while that of acid
rain is below 5.5. Acid rains are formed as a result of the reaction between water and sulfur (SO2)
ЕКОЛОГІЯ
https://doi.org/10.15407/dopovidi2020.07.092
UDC 581.143.6
I.V. Kosakivska, L.M. Babenko,
К.О. Romanenko, O.A. Futorna
M.G. Kholodny Institute of Botany of the NAS of Ukraine, Kyiv
E-mail: irynakosakivska@gmail.com, lilia.babenko@gmail.com,
katerynaromanenko4@gmail.com, oksana_drofa@ukr.net
Effects of exogenous bacterial quorum sensing
signal molecule (messenger) N-hexanoyl-L-homoserine
lactone (C6-HSL) on morphological and physiological
responses of winter wheat under simulated acid rain
Presented by Academician of the NAS of Ukraine V.V. Morgun
This research aims to investigate the influence of foliar treatment by bacterial quorum sensing signal molecule/mes-
senger N-hexanoyl-L-homoserine lactone (C6-HSL, 100 ng/ml) on morphological and functional characteristics of
Triticum aestivum L. cv. Yatran 60 leaves under simulated acid rain (SAR). Acid rain is one of the most dangerous
abiotic stressor, which negatively affects the plant growth and development. It changes the permeability and photo-
chemical activity of membranes, leads to the disruption of a chloroplast ultrastructure, stomata system functioning,
reduces CO2 photofixation. Using the scanning electron microscopy, we identified that, after the foliar treatment
by C6-HSL, the thickness of the leaf cell wall along with the cuticle layer in 20-day-old plants increased by 15 %.
Under SAR condition, the plants have suffered the disruption of the cuticular wax layer and uneven wax plates on
the epidermis surface, whereas the plants treated with C6-HSL showed only a partial cracking of the cuticular wax
layer, slight disruption of wax plates, and formation of a wax shell. The C6-HSL-treated plants showed the normal
functioning of stomata guard cells and the stabilization in the content of photosynthetic pigments. The protective
effect of the foliar treatment with C6-HSL solution in winter wheat plants under SAR and perspective of its using
for the induction of stress resistance has been discussed.
Keywords: Triticum aestivum, acid rain, N-hexanoyl-L-homoserine lactone, cell wall, epidermis microstructure,
photosynthetic pigments.
93ISSN 1025-6415. Допов. Нац. акад. наук Укр. 2020. № 8
Effects of exogenous bacterial quorum sensing signal molecule (messenger) N-hexanoyl-L-homoserine lactone...
and nitrogen (NOx) oxides, which are converted into sulfuric, sulfurous, nitrous, and nitric acid
solutions and get into the ground as meteorological precipitation. Rainfall is substantially (up to
60 %) oxidized with anion SO4
2–, which is involved in the oxidation processes that are characte-
rized by free radicals involvement. By oxidizing polyunsaturated fatty acids of cell membranes,
free radicals change their permeability, adversely affect the physiological and biochemical proc-
esses, and damage the guard cells of stomata. As a result, the stomata remain open or half open,
transpiration intensifies, the flow of toxins increases, and photosynthetic cells are damaged [2, 3].
At pH 2.0, plant damage becomes noticeable, dry biomass, photosynthetic fixation, and photo-
chemical activity are decreased [4]. Acid rains cause significant changes in the membrane system
of chloroplasts: inhomogeneous allocation of thylakoids inside grana, increasing the distance be-
tween thylakoids, thickening of grana thylakoids, disrupted connection between thylakoids
and stroma grana. Disturbances in the functioning of individual parts of the photosynthetic ap-
paratus are observed, and the carboanhydrase activity is reduced [5]. Acid rain was reported
to reduce the net intensity of photosynthesis of Cucumis sativus L. plants, which was associated
with a decrease in the maximum potential and effective quantum yield of the photosystem II
reaction center. Under these conditions, the activity of peroxidase and superoxide dismutase
increased, and the activity of catalase with an increased malondialdehyde content decreased.
These results indicate an indirect effect of acid rain on the photosystem II reaction center, which
is realized through the peroxidation of lipids and proteins in the thylakoid membrane [6].
N-acyl homoserine lactones (АHLs) belong to the class of bacterial quorum sensing signal
molecules involved in a distance signal transduction between bacteria-colonizers of plants and
bacteria and plant [7]. In recent years, special attention of researchers is paid to the participa-
tion of AHLs in the regulation of plant growth and development. Last studies have demonstra-
ted direct (on plants) and indirect (on rhizosphere microflora) effects of AHLs, which offer the
challenge for using these compounds in biotechnology for seed priming, and for foliar treatment
of plants, in modeling of protective reactions, and induction of genetic resistance [8, 9]. The aim
of our work was to study the protective effects of exogenous N-hexanoyl-L-homoserine lactone
(C6-HSL) on the microstructure of the leaf lamina surface and on the photosynthetic pigment
content in winter wheat plants under the simulated acid rain.
Materials and methods. The plants of short-stemmed, mid-early bare, soft wheat cv. Ya tran 60,
recommended for cultivation in the Forest-Steppe, Polesie, and Steppe regions of Ukraine were
studied. The grains were obtained from the collection of the Institute of Plant Physiology and
Genetics of the NAS of Ukraine. The calibrated grains were sterilized in 80 % ethanol solution,
washed with distilled water, placed in a cuvette with water for 3 h, and then germinated in a ther-
mostat on filter paper moistened with distilled water at +24 °C for 21 h.
The germinated grains were planted in 2-liter containers. Calcinated river sand was used as
the substrate. The plants were grown under controlled conditions at + 20/17 °C (day / night),
light intensity 690 μmol / (m2 ⋅ s), photoperiod 16/8 h (day/night), relative humidity of 65 ± 5 %,
the substrate humidity was maintained at 60 % of the total humidity. Irrigation was performed
daily using a Knop solution (50 ml per container).
On day 14, the plants were subjected to the foliar treatment with an aqueous solution of
C6-HSL, 100 ng/ml, and then kept for 4 days under the above-mentioned temperature and
light conditions. To prepare the mixture for simulated acid rain (SAR) NH4NO3 (1.3 g/l),
94 ISSN 1025-6415. Dopov. Nac. akad. nauk Ukr. 2020. № 8
Kosakivska I.V., Babenko L.M., Romanenko К.О., Futorna O.A.
MgSO4 ⋅ 7H2O (3.1 g/l), Na2SO4 (2.5 g/l), KHCO3 (1.3 g/l), CaCl ⋅ 2H2O (3.1 g/l) were used.
Obtained solution was diluted with 1 : 100 water and brought pH to 2.8, using 0.3 М H3PO4
and 0.2 M H2SO4, and tween 80 (0.5 % v/v) was added as a surfactant [4].
A mixture of SAR salts (pH 5.6) was used as a control. On day 18, C6-HSL treated and con-
trol plants were sprayed with an aqueous solution of a mixture of SAR (pH 2.8) and an aqueous
solution of a mixture of salts (pH 5.6) for three minutes and then kept for 2 days under the abo-
ve-mentioned temperature and light conditions.
Leaf samples were examined using a scanning electron microscope (SEM) JEOL JSM-6060
LA (Japan). The material was dehydrated in solutions of ethyl alcohol of increasing concent-
ration. After the treatment with absolute alcohol, it was transferred and glued to the object tables
with an adhesive tape, frozen in liquid nitrogen and dried to air-dry state in a freeze-dryer. In
order to give them conductivity, they were coated with a layer of gold in an ion pollinator. The
dimensions of the structures in the microphotographs were determined using the UTHSCSA
Image Tool 3.0 with a scale bar set on the image.
Photosynthetic pigments were extracted with 80 % acetone and detected by the method of
Wellburn [10]. The experiments were performed in two biological and three analytical replica tes.
The significance of the difference was assessed by Student’s t-test using a 5 % significance level
(P 0.05, P 0.001). The values presented correspond to the mean and their standard errors.
Results and discussion. Adaptation of plants is controlled by a molecular genetic system
that provides support for homeostasis and protects cellular components from destruction under
Fig. 1. Cross-section of leaf Triticum aestivum L. cv. Yatran 60 under SEM: cell walls of
leaf epidermis with cuticle layer in control (a); after foliar treatment with C6-HSL (b);
SAR (c); pre-treatment with C6-HSL followed by SAR (d)
95ISSN 1025-6415. Допов. Нац. акад. наук Укр. 2020. № 8
Effects of exogenous bacterial quorum sensing signal molecule (messenger) N-hexanoyl-L-homoserine lactone...
extreme external conditions. Leaf, as an organ that exhibits phenotypic plasticity, is one of the
universal models for studying the effect of stressors. Our studies have shown that the thickness
of the cell wall of the leaf epidermis, along with the cuticle layer of 20-day-old wheat plants, varies
depending on the type of foliar treatment (Fig. 1). It is noted that the cell wall thickness of 20-
day-old plants treated solely with C6-HSL was increased by 15 % relative to the control. On the
contrary, the treatment with SAR caused a significant thinning of the cell wall by 33 %, while the
pretreatment with C6-HSL followed by SAR reduced wall thickness of cells only by 9 % (Fig. 2).
The epidermal tissue of the cereal leaves is formed by the epidermal cells, trichomes, and sto-
mata. Paracytic stomata are present on both epidermises; to every dumbbell-like guard cell, one
semilunar near stomatal cells is connected. We found that both the adaxial and abaxial epider-
mises in leaf lamina of 20-day winter wheat control plants are characterized by the presence of a
well-developed layer of wax (Fig. 3, a).
It is formed by multidirectional waxy uneven plates and is observed on all epidermal cells
covering basal part of trichomes and stomata guard cells. A well-developed layer of wax is also
observed on outer periclinal walls of cells of both epidermises after the foliar treatment with a
solution of C6-HSL (Fig. 3, b). The type of wax deposits on the leaf blade did not change com-
pared with the control (Fig. 3, b). In all specimens subjected to the foliar treatment with SAR, the
significant destruction of the epicuticular wax layer on both surfaces of the leaf till its complete
disappearance is observed (Fig. 3, c, indicated by arrows). Because of a damage to stomata guard
cells, up to 30 % of stomata on the surface of the leaf lamina, affected by acid rain, remained open.
At the same time, epicuticular wax was not significantly damaged in wheat leaves pre-treated
with C6-HSL after the SAR treatment (Fig. 3, d). There is a slight destruction of the wax plates
and the formation of wax crusts on the adaxial surface of the leaves (Fig. 3, d, indicated by ar-
rows). Guard cells of stomata were not damaged, stomata pore was closed. In general, no major
destructive changes have occurred.
Fig. 2. Epidermal cell wall thickness of leaves of Triticum aestivum L. cv. Yatran 60 with cuticle layer in control (1)
and after foliar treatment with C6-HSL (2), SAR (3) and pre-treatment with C6-HSL followed by SAR (4).
* Sig nificant differences between the control and experimental groups for Р 0.001 (n = 100).
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Kosakivska I.V., Babenko L.M., Romanenko К.О., Futorna O.A.
Cuticular wax plays a vital role for plants, protecting them from abiotic and biotic stresses
[11]. Waxes create a continuous hydrophobic barrier to reduce water loss from plant organs and
function as the first protective line to reduce the loss of “non stomata” moisture. Reflecting capac-
ity of epicuticular wax regulates temperature and reduces water loss of plants. In addition, epicu-
ticular wax reflects a drop of water, which often carries fungal spores and dust particles [12]. It has
been already established that the waxes degrade under the action of atmospheric pollutants: their
chemical composition changes, the aging of the cuticle accelerates, which leads to its destruction.
It has been found that there are two ways of pollutant action: 1) direct interaction of the wax
components with atmospheric toxicants and 2) indirect disruption of the development of cuticle
and epicuticular waxes. Erosion of epicuticular waxes increases cuticular transpiration, which in
turn, increases the negative effect of atmospheric pollutants and reduces the viability of leaves [13].
It was reported earlier [8] that, after the exogenous treatment of Arabidopsis leaves with a
solution of N-3-oxo-tetradeconoyl-L-homoserlinactone (oxo-C14-HSL), stomata closed, and the
cell wall thickened. State of stomata guard cells is known to be mainly controlled by abscisic acid
(ABA). It was found that, after the treatment with oxo-C14-HSL, components of oxylipin/sali-
cylate-dependent signaling pathway but not ABA-dependent one were involved in regulation of
stomata apparatus activity [8].
One of the negative effects of acid rain is a decrease in the content of photosynthetic pig-
ments. The pigment complex actively responds to the environmental signals, and changes in the
Fig. 3. Ultrastructure of leaf surface of Triticum aestivum L. cv. Yatran 60: a – control; b — after the foliar treat-
ment with C6-HSL (B); c — after the SAR (pH 2.8), the arrows indicate the destruction of epicuticular wax
layer until it disappears completely; d — after the pre-treatment with C6-HSL followed by SAR (pH 2.8), the
arrows indicate a slight destruction of the wax plates
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Effects of exogenous bacterial quorum sensing signal molecule (messenger) N-hexanoyl-L-homoserine lactone...
content/ ratio of the pigments serve as a test evaluating the influence of a certain factor on the
plant condition. We found tha, after the foliar treatment with C6-HSL solution, the content of
photosynthetic pigments was increased significantly, especially, chlorophyll a – by 35 % and chlo-
rophyll b — by 37 % (Fig. 4). On the other hand, in the experiment with SAR, the content of photo-
synthetic pigments on winter wheat leaves was significantly reduced. Chlorophyll a, as the an-
tenna and the reaction center core in both photosystem I (FS I) and photosystem II (FS II), plays
a crucial role. Chlorophylls were more sensitive to the SAR treatment: the content of chlorophyll
а decreased by 29 %, chlorophyll b — by 35 % (Fig. 4). Foliar treatment of wheat leaves with
C6-HSL solution significantly mitigated the negative effect of SAR. Thus, the content of chlo-
rophyll а decreased by 15 %, chlorophyll b — by 11 %. Other researchers [14] reported that
Fig. 4. The content of photosynthetic pigments in leaves of 20-day-old Triticum aestivum cv. Yatran 60 variety
in control (1) and after the foliar treatment with C6-HSL (2), SAR (3) and the pre-treatment with C6-HSL
with subsequent SAR treatment (4). *, **, *** — P 0.05 (n = 16) compared with the corresponding control
Influence of simulated acid rain on the ratio of photosynthetic pigments
in leaves of 20-day-old Triticum aestivum cv. Yatran 60
Sample
Chl (a + b) mg/g
of fresh weight
Chl а/b Chl (a + b)/car
Control 1.798 ± 0.113 1.98 5.87
SAR 1.255 ± 0.081* 2.12 4.56
C6-HSL+SAR 1.555 ± 0.102* 1.9 5.45
C6-HSL 2.444 ± 0.122* 1.96 6.85
* Significant differences between the control and experimental groups for Р 0.05 (n = 16).
98 ISSN 1025-6415. Dopov. Nac. akad. nauk Ukr. 2020. № 8
Kosakivska I.V., Babenko L.M., Romanenko К.О., Futorna O.A.
overall, as the acidity of precipitation per unit pH was increased, the chlorophyll content in leaves
of trees, shrubs, and grasses was decreased by 6.71 %. At the same time, no significant difference
in the fluctuation of the chlorophyll content under acid rain was found between the species of
calcephiles, calcephobes, and ubiquists, indicating that there is no correlation between soil acid
sensitivity and leaf damage by acid rain [14]. Carotenoids (Table) were the least sensitive to
SAR, which, as components of the antioxidant system, are involved in the detoxification of oxi
dative stress pro ducts. Similar effects of acid rain on the content of photosynthetic pigments in
Lolium perenne L. plants have been reported in [15].
The total number of chlorophylls a+b in the leaves of wheat under the action of SAR
was decreased by 1.4 times relative to the control (Table), indicating a decrease in photochemical
activity. In the experiment with the C6-HSL pretreatment and subsequent SAR, changes in the
amount of chlorophylls a+b are insignificant (by 1.16 times, see Table), which indirectly indicates
the protective effect of C6-HSL on the photosynthetic apparatus of cells under the conditions of
such aggressive stressor as SAR. It should be noted that the sum of chlorophylls a+b in wheat
leaves treated exclusively with C6-HSL was increased by 1.36 times, indicating a positive effect of
C6-HSL on the photochemical activity. The degree of formation and functioning of the photosyn-
thetic apparatus under the action of unfavorable environmental factors characterizes the indica-
tor of the ratio between chlorophylls а and b. Due to the action of SAR, the ratio a/b is the high-
est (Table) as the content of chlorophyll b is reduced, which, in turn, negatively affects the func-
tioning of light-harvesting complexes of FS I and FS II. The ratio of chlorophylls a+b/car is an
informative indicator of the intensity of damage caused on photosynthetic apparatus. The lower
the ratio, the greater the damage caused by aging or stress. We found that, under the SAR con-
ditions, the ratio of chlorophylls a+b/car was decreased by 23 %, whereas, after treatment with
C6-HSL with subsequent SAR, the ration is decreased by 7 % (Table). In the experiment with
only the foliar treatment with C6-HSL, the a/b index differs significantly from the control; the
value of a+b/car was increased by 16 % (see Table), which indirectly evidences the stabilization
and strengthening of the photosynthetic apparatus under the influence of C6-HSL.
Acid rain is a serious problem for the environmental balance in the world that interferes
with plant growth and developments. Various physiological and morphological characteristics of
plants have been negatively affected by acid rain.
The results of our study indicate that simulated acid rain (pH 2.8) caused the damage to sto-
mata guard cells, complete destruction of the wax plates on the epidermis of leaf surface, and sig-
nificantly suppresses chlorophyll content. The foliar treatment of wheat with an aqueous solution
of bacterial quorum sensing signal N-hexanoyl-L-homoserine lactone resulted in a partial crack-
ing of the cuticular wax layer, slight destruction of the wax plates, and formation of wax crusts.
The stomata were closed and the content of photosynthetic pigments was stabilized.
Thus, our results demonstrate the protective effect of the foliar treatment with C6-HSL solu-
tion of winter wheat plants under SAR and perspective of its using for the induction of a stress
resistance.
The paper is based on the results of the project № 0120U102936 “Development of innovative
biotechnology for increasing the stability and productivity of cereals based on a complex of signaling
molecules of plant and bacterial origin for environmental protection and restoration” (2020—2024)
funded by the National Academy of Sciences of Ukraine.
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Effects of exogenous bacterial quorum sensing signal molecule (messenger) N-hexanoyl-L-homoserine lactone...
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Received 27.04.2020
Kosakivska I.V., Babenko L.M., Romanenko К.О., Futorna O.A.
І.В. Косаківська, Л.М. Бабенко,
К.О. Романенко, О.А. Футорна
Інститут ботаніки ім. М.Г. Холодного НАН України, Київ
E-mail: irynakosakivska@gmail.com, lilia.babenko@gmail.com,
katerynaromanenko4@gmail.com, oksana_drofa@ukr.net
ВПЛИВ ЕКЗОГЕННОЇ ОБРОБКИ ВОДНИМ РОЗЧИНОМ
СИГНАЛЬНОЇ МОЛЕКУЛИ-МЕДІАТОРА БАКТЕРІАЛЬНОГО
ПОХОДЖЕННЯ N-ГЕКСАНОЇЛ-L-ГОМОСЕРИНЛАКТОНУ (C6-ГГЛ)
НА МОРФОЛОГІЧНІ ТА ФІЗІОЛОГІЧНІ РЕАКЦІЇ ОЗИМОЇ ПШЕНИЦІ
ЗА УМОВ ДІЇ МОДЕЛЬОВАНОГО КИСЛОТНОГО ДОЩУ
Досліджено вплив фоліарної обробки водним розчином сигнальної молекули-медіатора бактеріального
походження N-гексаноїл-L-гомосеринлактону (C6-ГГЛ, 100 нг/мл) на структурно-функціональні харак-
теристики Triticum aestivum L. сорту Ятрань 60 за умов дії модельованого кислотного дощу (МКД). Кис-
лотні дощі належать до найнебезпечніших абіотичних стресорів, які негативно впливають на ріст і розви-
ток рослин. Наслідком кислотного дощу є зміна проникності мембран, порушення в ультраструктурі хло-
ропластів, функціонуванні продихової системи, зниження фотофіксації CO2 і фотохімічної активності.
Методом сканувальної електронної мікроскопії встановлено, що товщина клітинної стінки разом із шаром
кутикули у 20-добових рослин, оброблених C6-ГГЛ, збільшилась на 15 %. Під дією МКД у рослин руйну-
вався шар кутикулярного воску і нерівнокраї воскові пластинки на поверхні епідермісу, тоді як у рослин,
що були оброблені C6-ГГЛ, спостерігалося лише часткове розтріскування шару кутикулярного воску, не-
значне руйнування воскових пластинок і формування воскових кірок. У рослин, оброблених C6-ГГЛ, за-
фіксоване нормальне функціонування замикаючих клітин продихів і стабілізація у вмісті фотосинтетич-
них пігментів. Обговорюється захисний ефект фоліарної обробки розчином C6-ГГЛ рослин озимої пше-
ниці в умовах МКД та перспективи використання цієї речовини для підвищення стресостійкості.
Ключові слова: Triticum aestivum, кислотний дощ, N-гексаноїл-L-гомосеринлактон, клітинна стінка, мікро-
структура епідермісу, фотосинтетичні пігменти.
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