Добавил:
Sekretar
kiopkiopkiop18@yandex.ru
t.me/Prokururor I Вовсе не секретарь, но почту проверяю
Опубликованный материал нарушает ваши авторские права? Сообщите нам.
Вуз:
Предмет:
Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5968_Библиотеки_им_академика_М_И_Перельмана
.pdf
275
Role of Phytomelatonin in Plant Tolerance
Under Environmental Stress
16
Sachin Kumar, Akanksha Pandey, Monika Singh, Sudhanshu Mishra,
Sandeep Kumar, Navneet Bithel, and Minakshi Rajput
Abstract
Phytomelatonin, a recently discovered unique novel plant growth regulator is
widespread among plants with a broad range of phenotypic manifestations and
plays several physio-morphological functions in plants. Though melatonin is
derived from both animals and plants, it is manufactured inside the cell, especially
in chloroplast and mitochondria from tryptophan amino acid. It is a versatile
signaling molecule that potentially triggers a sequence of events required to
reduce stress conditions in plants. It is an evolutionary conserved pleiotropic
bioprotectant that promotes stress tolerance in plants by directly scavenging
reactive oxygen species (ROS) or reactive nitrogen species (RNS) due to various
physiochemical (heat, cold, water deficit, waterlogging, heavy metal, and several
others) and biological (viral, bacterial, and fungal-me diated) environmental
stresses. Along with this, phytomelatonin stimulates the free radical-antioxidant
defense system, promotes the plant photosynthesis efficiency, enhances stomatal
conductance, regulates genes related to stress resistance, and helps in protecting
the plant from pathogenic infections by triggering the release of some stress-
induced hormones such as jasmonic acid (JA), ethylene, salicylic acid (SA), etc. It
S. Kumar · A. Pandey · S. Kumar · N. Bithel
Department of Botany and Microbiology, Gurukula Kangri (Deemed to be University), Haridwar,
Uttarakhand, India
M. Singh · M. Rajput (
✉)
Department of Biotechnology, School of Applied and Life Sciences, Uttaranchal University,
Dehradun, Uttarakhand, India
S. Mishra
Department of Biotechnology, School of Applied and Life Sciences, Uttaranchal University,
Dehradun, Uttarakhand, India
School of Biosciences (SBS), Apeejay Stya University, Sohna, Gurugram, Haryana, India
#
The Author(s), under exclusive license to Springer Nature Singapore Pte
Ltd. 2023
D. Singh et al. (eds.), Stress-responsive Factors and Molecular Farming
in Medicinal Plants,
https://doi.org/10.1007/978-981-99-4480-4_16
https://t.me/medicina_free
induces transcription of genes associated with various physio-morphological
processes including rooting, seedling germination, fruit ripening, senescence,
and circadian rhythm. In this chapter, we have summarized the protective mech-
anism of phytomelatonin against diverse abiotic and biotic stress along with its
uses for enhancing plant stress resistance.
276 S. Kumar et al.
Keywords
Phytomelatonin · Stress tolerance · Bioprotectant · Physio-morphological ·
Tryptophan
16.1 Introduction
Melatonin (MEL) is a multifunctional ubiquitous biomolecule distributed from
prokaryotes to animals and plants. It is an N-acetyl-5-methoxy tryptamine, an indole
derivative compound that plays an important part in regulating free radical scaveng-
ing system, circadian cycle, Alzheimer’ s disease, cardiac disorders, as well as the
physiological and hormonal balance of animals (Lerner et al. 1960). It also acts as an
animal hormone that controls anticancer and antiaging properties, the immune
system, sleeping promotion, and associated disorders. Since first reported in animals
(pineal glands of dairy cows) in 1958, melatonin was also discovered in
microorganisms and plants in the late 90s (Manchester et al.
2015).
MEL was found in 1991 in the photosynthetic dinoflagellate Lingulodinium
polyedrum, also referred to as Gonyaulax polyedra. This work increased scientists’
attention to discovering MEL in other plants, and in 1993 it was found in Pharbitis
nil. However, this research could not be published until 199 (Khan et al.
2020). The
plant melatonin, also known as “phytomelatonin” is a multi-regulatory molecule
found almost in all parts of the plant and responsible to control growth, development,
flowering, seed germination, and senescence (Murch and Erland
2021). Researchers
reported the important role of phytomelatonin in plant defense against damage
caused by the environmental stresses (Arnao and Hernández-Ruiz
2019). Abiotic
stress harms plants, restricting growth and productivity, and in response to that, a
variety of physiological and metabolic changes occur in plants to sustain themselves
(Kumar et al. 2019). Phytomelatonin directly scavenges ROS and RNS generated by
diverse abiotic stressors as cold, heat, drought, salt, herbicides, heavy metal, UV
rays, and pathogenic infections. The overabundance of ROS and RNS under stress
can cause damage to cell membranes, denaturation of DNA and proteins, carbohy-
drate oxidation, lipid peroxidation, pigment degradation, and abnormal enzyme
function (Moustafa-Farag et al.
2019). However, during acute stress situations, the
mechanisms of phytomelatonin-alleviating stress differ depending on the kind of
stress (Sun et al.
2021). Phytomelatonin is very protective against a variety of abiotic
stimuli, but its effects on biotic tolerance have not been well understood
(Elmahallawy et al. 2014). During the past 10 years, the significance of melatonin
in indirect inhibition pathogenic microorganisms of plants and the development of
https://t.me/medicina_free
acquired resistance in crops has received extensive attention (Chen et al. 2019). In
addition to insects and plant-parasitic nematodes, phytomelatonin showed high
efficiency against fungal, bacterial, and viral infections (Vielma et al. 2014). The
activation of defens e genes, ROS/RNS scavenging, cell wall thickening, and hor-
monal release is the main mechanism engaged in regulating effect of biotic stress on
plants (Prakash et al.
2019). Increased callose deposition and cellulose, galactose,
and xylose accumulation in plants treated with melatonin have resulted in many
biochemical defense mechanisms against several microorganisms (Zhao et al.
2015).
It has been found that plants’ defensive mechanisms were stimulated by the syner-
gistic effects of melatonin and serotonin (Saremba et al.
2017). However, further
research is necessary to understand the molecular mechanism of synergistic
interaction.
16 Role of Phytomelatonin in Plant Tolerance Under Environmental Stress 277
Can the process of phytomelatonin-mediated tolerance for one stress be applied to
other stresses, and can it be understood from the standpoint of cross-adaptation? This
chapter discusses phytomelatonin biosynthesis, metabolism, mode of action, signal-
ing pathways, and research advances on these points concerning plant tolerance
toward stress, as well as future application potential.
16.2 Phytomelatonin Synthesis and Metabolism
Phytomelatonin is a mol ecule synthesized by several plants and is structurally
similar to the horm one melatonin, which is usually manufactured and released by
the pineal gland in mammals. The biosynthetic pathway of phytomelatonin synthesis
in plants involves several sequential reactions that lead to the formation of the final
product. The main precursor molecule for the biosynthesis of phytomelatonin is
tryptophan, an essential amino acid (Kanwar et al. 2018). The process involves a
series of enzyme-catalyzed reactions that convert the amino acid tryptophan into
melatonin. Tryptophan is synthesized from chorismic acid (obtained de novo via the
shikimate pathway) in a reaction catalyzed by the enzyme tryptophan synthase
(Mannino et al.
2021). The decarboxylation of tryptophan resulted in the formation
of tryptamine by the action of the enzyme tryptophan decarboxylase (TDC).
Hydroxyl (-OH) group was added to tryptamine by tryptamine 5-hydroxylase
(T5H) that gives a key central compound of these pathways, i.e., serotonin. Further-
more, the N-acetyl group from acetyl CoA is transferred to serotonin-by-serotonin
N-acetyl transferases (SNAT) which yield N-acetyl-serotonin. The acetylated sero-
tonin undergoes an O-methylation reaction to form a melatonin molecule under the
control of enzymes hydroxy indole-O-methyltransferase (HIOMT) or N-acetyl-
serotonin methyltransferase (ASMT) (Wang et al.
2020).
In an alternative pathway, serotonin is converted into 5-methoxy-tryptamine by
the HIOMT enzyme and further transformed into melatonin by the SNAT enzyme.
Besides this, melatonin is also biosynthesized from N-acetyl tryptamine where a
reaction catalyzed by the SNAT enzyme this pathway is still not well unders tood,
and more research is needed to determine. All the abovementioned enzymes in the
melatonin biosynthetic pathway are distributed among chloroplasts, mitochondria,
https://t.me/medicina_free
endoplasmic reticulum, and cytoplasm of the plant cells (Back et al. 2016). TDC,
ASMT, and COMT enzymes are localized in the cytoplasm, whereas SNAT is
produced inside the chloroplast. The endoplasmic reticulum also contains the T5H
enzyme and also acts as a site of synthesis of serotonin despite cytoplasm. In fact,
under normal or stressful condition that does not induce large serotonin buildup in
the cell, phytomelatonin synthesis pathways begin from tryptophan and moves
through intermediate compounds (such as tryptamine, serotonin,
N-
acetylserotonin) to melatonin. The amount of serotonin remains quite low and
the SNAT enzyme selectively acetylates serotonin due to its higher affinity as
compared to ASMT and COMT (Back et al. 2016; Byeon et al. 2016). Paradoxically,
under adverse biotic and abiotic stress conditions as well as during the period of
plant senescence, the amount of intermediate products increases, and melatonin is
synthesized through the O-methylation of serotonin by COMT and acylation of
serotonin occurred by the action of SNAT enzyme (Wang et al.
2020). This
biosynthetic pathway occurs in the chloroplasts and cytoplasm of the plant cells.
The final product, phytomelatonin, is involved in various physiological functions as
regulating the circadian rhythm, mediating photoperiodic responses, and controlling
the responses to various environmental stress conditions (Takahashi and Murata
2008). Figure 16.1 shows the enzymes involved in tryptophan into melatonin
transformation and subcellular localization of intermediates via four types of
pathways, with the involvement of chloroplast, cytoplasm, and endoplasmic
reticulum.
278 S. Kumar et al.
16.3 Phytomelatonin Signaling Pathway and Its Mechanism
of Action
Phytomelatonin in plants may produce and signal two types of mechanisms which
are exogenous and endogenous. In the exogenous type, the plant can absorb melato-
nin from the soil or other external sources. Phytomelatonin is synthesized in plants
from tryptophan, an amino acid, and its production can be influenced by a wide
range of physiological and environmental factors (Huang et al. 2022). One exoge-
nous mechanism of action that has been shown to influence phytomelatonin secre-
tion is light. Specifically, exposure to different wavelengths of light can stimulate or
inhibit the production and relea se of phytomelatonin in plants. For example, blue
light has been shown to increase phytomelatonin production in some plant species,
while red light can have the opposite effect. Other environmental factors, such as
temperature and humidity, may also affect phytomelatonin secretion (Wang et al.
2018).
In endogenously, the plant can produce melatonin within its tissues, through the
action of the enzyme serotonin N-acetyltransferase. Melatonin production occurs in
response to environmental stress by regulating water balance and reducing water
loss. Both exogenous and endogenous mechanisms work together to enhance the
tolerance capacity of plants to environmental stress such as drought, cold, etc., by
https://t.me/medicina_free
16 Role of Phytomelatonin in Plant Tolerance Under Environmental Stress 279
Fig. 16.1 Enzymes involved in tryptophan into melatonin transformation and subcellular locali-
zation of intermediates (a) Biosynthesis of melatonin by route 1 (melatonin 1) and 2 (melatonin2)
through chloroplast, cytoplasm, and endoplasmic reticulum in plants. (b) Biosynthesis of melatonin
by routes 3 (melatonin 3) and 4 (melatonin 4) through chloroplast and cytoplasm in plants. TPH
tryptophan hydroxylase, TDC L-tryptophan decarboxylase, T5H tryptamine 5-hydroxylase, ASMT
acetylserotonin O-methyltransferase, SNATs serotonin N-acetyltransferase, COMT caffeic acid
3-O- methyltransferase
https://t.me/medicina_free
activating the melatonin signaling pathway (Zhang et al. 2015; Byeon and Back
2014).
280 S. Kumar et al.
16.4 The Role of Phytomelatonin in Response to Abiotic Stress
Phytomelatonin eradicates the negative impact of abiotic stress in plants. It can act as
an antioxidant agent by reducing oxidative stress produced by abiotic stress factors
including extreme temperatures, high salinity, etc. (Zhang et al.
2015). Plants can
respond to abiotic stress conditions in various ways, depending on the type and
severity of the stress. Table
16.1 represents vario us types of abiotic stress on plants
with their effect. According to Wang et al. (Wang et al.
2018), some common
responses include:
1. Altering gene expression. Plants can alter certain gene expression in response to
abiotic stress, which can help them to adapt against stress and survive).
2. Closi ng stomata. During abiotic stress (drought or extreme temperatures), plants
can close their stomata to conserve water and prevent excessive water loss.
3. Produci ng osmoprotectants. Osmoprotectants are molecules that help protect
cells from damage caused by abiotic stress. Plants can produce osmoprotectants
such as glycine betaine, proline, and sugars in response to stress.
4. Activating stress response. Plants have evolved various stress response pathways
that can be activated at the time of abiotic stress. For example, the plant hormone
abscisic acid is involved in abiotic stress response pathways and can help plants to
adapt to drought and other stress conditions.
16.4.1 Light as a Stress Factor
Light can act as a factor that may cause stress in plants when it exceeds or falls short
from the optimal level required for normal growth and develo pment or when it’s too
much intense or too mild and when its quality or duration of exposure changes
abruptly. Different plants have different light requirements, but in general, too much
or too little light can cause stress to plants. Excessive light, especially in the UV-B
range, can lead to photooxidative stress in plants. This stress occurs when the excess
light energy causes damage to the photosynthetic machinery of the plant, leading to
the production of ROS as singlet oxygen and superoxide radicals. These ROS are
responsible for cellular damage and lead to plant cell death. On the other hand,
insufficient light can also cause stress to plants. Low light levels can limit photosyn-
thesis and reduce the production of energy and nutrients that plants need for growth
and development. This can result in a reduction in plant size, delayed growth and
development, and even death in severe cases. For instance, plants may undergo
oxidative stress from excessive light exposure, which can harm their cells and hinder
https://t.me/medicina_free
(continued)
16 Role of Phytomelatonin in Plant Tolerance Under Environmental Stress 281
Table 16.1 Role of melatonin in abiotic stress tolerance in plants
Sr.
no.
Stress
condition Plant Mechanism
Melatonin
in plant
organ Effect Reference
1. High
temperature
Soyabean, Glycine max Exogenous
melatonin
– Increased activities of CAT, SOD Imran et al. (2021)
2. High
temperature
Wheat, Triticum
aestivum
Endogenous
melatonin
Seed Reduced H
2
O
2
accumulation and increased
proline contents accumulation
Buttar et al. (2020)
3. High
temperature
Tomato, Solanum
lycopersicum
Endogenous
melatonin
– Increased activities of APX, POD CAT. Jahan et al. (2019)
4. High
temperature
Fuzzy kiwifruit,
Actinidia deliciosa L.
Exogenous
melatonin
– Reduced H
2
O
2
contents and enhance
expression
levels
Liang et al. (2018)
5. High
temperature
Ryegrass, Lolium
perenne
Exogenous
melatonin
– Increased chlorophyll content,
photosynthetic rate, membrane stability,
plant height and biomass
Zhang et al. (2017a)
6. Cold Cashew, Pistacia vera Exogenous
melatonin
– Chlorophyll degradation reduction and
increased photosynthesis
Barand et al. (2020)
7. Cold Tea tree, Camellia
sinensis
Endogenous
melatonin
Leaves Increased activities of SOD, CAT, CAT,
and GSH
Li et al. (2019a)
8. Cold Garden tomato,
Lycopersicon
esculentum L.
Exogenous
melatonin
Seed Protects the photosynthetic apparatus Yang et al. (2018)
9. Cold Mango, Mangifera
indica
Endogenous
melatonin
– Downregulated DAO and upregulated
ADC
Bhardwaj et al. (2022)
10. Cold Golden root, Rhodiola
crenulata
Exogenous
melatonin
– Enhances cryopreservation of callus
Zhao et al. (
2011)
11. Cold Wheatgrass, Elymus
nutans
Exogenous
melatonin
– Downstream cold-responsive genes and
regulates abscisic acid
Fu et al. (
2017)
https://t.me/medicina_free
Table 16.1 (continued)
Sr.
no.
Stress
condition Plant Mechanism
Melatonin
in plant
organ Effect Reference
12. Cold Cucumber, Cucumis
sativus
Exogenous
melatonin
Cortex Increases ascorbic acid and glutathione
levels
Marta et al. (2016)
13. Cold Watermelon, Citrullus
lanatus
Exogenous
melatonin
– Increases photosynthesis Li et al. (2016)
14. Cold American elm, Ulmus
americana
Exogenous
melatonin
– Increment in the regrowth rate of
cryopreserved seeds
Uchendu et al. (2013)
15. Drought Naked oats or hulless
oats, Avena nuda
Exogenous
melatonin
Seed
(embryo)
Increases mitogen-activated proteins kinase
and transcription factors
Gao et al. (2018)
16. Drought Wheat, Triticum
aestivum
Exogenous
melatonin
Seed Increases plant stature, total plant mass,
root development
Ni et al. (2018)
17. Drought Turmeric, Curcumin
sativus
Exogenous
melatonin
Cortex Increases root growth and germination rate Zhang et al. (2013)
18. Drought Maize or corn, Zea mays Exogenous
melatonin
Fruit Increases photosynthetic efficiency and
strengthen antioxidant defense system
Ahmad et al. (2019),
Huang et al. (2019)
19. Drought Moldavian balm
Dracocephalum
moldavica
Exogenous
melatonin
Tuber Enhanced photosynthesis and chlorophyll
potential and decrease oxidative stress
Li et al.
(
2015)
20. Drought Grapevine, Vitis vinifera Exogenous
melatonin
Leaves Reduces ROS burst and increase seedling
growth, photosynthesis, osmoregulation
Meng et al. (2014)
21. Drought Soyabean, Glycine max Exogenous
melatonin
Root Enhanced antioxidative enzymes,
photosystem II
Efficiency and leaf area index
Zhang et al. (2019)
22. Drought Tomato, Solanum
lycopersicum
Endogenous
melatonin
Fruit Regulating stomatal closure, strengthening
root system, and antioxidant protection
Maggio et al. (2007)
23. Drought Barley, Hordeum
vulgare
Exogenous
melatonin
Fruit Enhanced germination rate, regulating
genes for antioxidative enzymes
Xie et al. (2021)
282 S. Kumar et al.
https://t.me/medicina_free
(continued)
24. Drought Apple, Malus domestica Exogenous
melatonin
Tuber Upregulation of SAG12 (senescence-
associated gene 12), regulate photosystem
II (PSII)
Wang et al. (2018)
25. Drought Drumstick tree or
horseradish tree,
Moringa oleifera
Exogenous and
endogenous both
type
Leaves Increase root growth, branching, osmotic
adjustment, and declined malondialdehyde
(MDA) contents
Sadak et al. (2020)
26. Drought Bermuda grass,
Cynodon dactylon
Exogenous
melatonin
– Decreases ROS, enhances antioxidant
metabolism, concentration of sugars, sugar
alcohols, amino acids, organic acids
Shi et al. (2015)
27. Drought
stress
Lemmon grass
Cymbopogon citratus
Exogenous
melatonin
Leaves Increase plant growth, enhanced oil
metabolism
Singh-sangwan et al.
(1994)
28. Alfalfa
Medicago sativa
Exogenous
melatonin
– Sugar contents, amino acid accumulation Schubert et al. ( 1995)
29. Drought Coffee bean, Coffea
arabica
Exogenous
melatonin
Fruits and
seeds
Regulate caffeine biosynthesis genes Campos et al. (2019)
30. Drought Transgenic
Arabidopsis
Exogenous
melatonin
Leaves Regulate expression of the wheat TaCOMT
gene
Yang et al. (2019)
31. Drought Ryegrass, Lolium spp. Exogenous
melatonin
– Induced, expression of PAO2, PAO4, and
PAO5
Fu et al. (2017)
32. Drought Tall fescue Festuca
arundinacea
Exogenous
melatonin
– Increase, root growth, antioxidant enzyme
activity, and reactive oxygen species level
Alam et al. (2018)
33. Drought Creeping bentgrass
Agrostis stolonifera
Exogenous
melatonin
– Increase photochemical efficiency,
chlorophyll content, and lipid peroxidation
Ma et al. (2018)
34.
Salt stress Chinese crabapple,
Malus hupehensis
Exogenous Tuber Enhanced leaf number, chlorophyll
content, shoot height, and electrolyte
leakage
Wang et al. (2018)
35. Salt stress Thale cress, Arabidopsis
thaliana
Endogenous – Increase lateral root development, regulates
auxin distribution
Chen et al. (2017),
Zheng et al. (
2017)
36. Salt stress Cucumber, Cucumis
sativus
Exogenous Cortex Increase germination of seeds enhanced the
levels of proteins for energy production
Wang et al. (2016)
16 Role of Phytomelatonin in Plant Tolerance Under Environmental Stress 283
https://t.me/medicina_free
Table 16.1 (continued)
Sr.
no.
Stress
condition Plant Mechanism
Melatonin
in plant
organ Effect Reference
37. Salt stress Sunflower, Helianthus
annuus
Exogenous
melatonin
– Increases antioxidant efficiency and root/
hypocotyl growth
Mukherjee et al.
(2014)
38. Salt stress Maize or corn, Zea mays Exogenous
melatonin
Fruit Germ and radicle growth, various
metabolic processes
Chen et al. (2018a)
39. Salt stress Cotton, Gossypium
hirsutum
Exogenous
melatonin
Flower Antioxidant enzymes activity Xiao et al. (2019)
40. Salt stress Wheat, Triticum
aestivum
Exogenous
melatonin
Seed Regulation of polyamine metabolism Ke et al. (2018)
41. Salt stress Rapeseed Brassica
napus
Exogenous
melatonin
Corm Upregulates antioxidant defense genes;
maintains redox and ion homeostasis
Zhao et al. (2019)
42. Salt stress Two-colored Sea
lavender, Bunge,
Limonium bicolor
Exogenous
melatonin
– Higher seed germination, increased
gibberellic acid and lowers abscisic acid
content
Li et al. (2019b)
43. Salt stress Brown mustard or
Indian mustard Brassica
juncea
Exogenous
melatonin
– Increased leaf length/width, plant height,
stem diameter, relative water content and
gas exchange parameters, salicylic acid
content; decreased abscisic acid content
Park et al. (2021)
44. Salt stress Rice, Oryza sativa Exogenous
melatonin
Seed Increased chlorophyll content, decreased
membrane lipid oxidation, sodium content,
maintain Na
+
/K
+
homeostasis
Xie et al. (2021)
45. Salt stress Common bean Vicia
faba
Exogenous
melatonin
– Increased photosynthetic rate, growth, and
osmolyte levels
Stoeva and
Kaymakanova (
2008)
46. Salt stress Tomato Solanum
lycopersicum
Endogenous
melatonin
Seed Enhanced lipid
peroxidation, antioxidants,
biomass production,
and limited ROS
production
Maggio et al. (2007),
Shalata and Tal (
1998)
284 S. Kumar et al.
https://t.me/medicina_free
Соседние файлы в папке Библиотека им академика М.И. Перельмана