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_5690_Библиотеки_им_академика_М_И_Перельмана
.pdf
11 Signaling Molecules in Medicinal Plants Response to Cold Stress 191
Taylor CB (1996) Proline and water deficit: ups, downs, ins, and outs. Plant Cell 8(8):1221
Terletskaya NV, Korbozova NK, Kudrina NO, Kobylina TN,
Kurmanbayeva MS, Meduntseva ND
et al (2021) The influence of abiotic stress factors on the morphophysiological and phytochemi-
cal aspects of the acclimation of the plant Rhodiola semenowii Boriss. Plan Theory 10(6):1196
Thakur P, Kumar S, Malik JA, Berger JD, Nayyar H (2010) Cold stress effects on reproductive
development in grain crops: an overview. Environ Exp Bot 67(3):429–443
Theocharis A, Clément C, Barka EA (2012) Physiological and molecular changes in plants grown at
low temperatures. Planta 235:1091–1105
Thomashow MF (1999) Plant cold acclimation: freezing tolerance genes and regulatory
mechanisms. Annu Rev Plant Biol 50(1):571–599
Tian J, Ma Y, Chen Y, Chen X, Wei A (2022) Plant hormone response to low-temperature stress in
cold-tolerant and cold-sensitive varieties of Zanthoxylum bungeanum maxim. Front Plant Sci
13:13
Tiwari S, Patel A, Singh M, Prasad SM (2020) Regulation of temperature stress in plants. In: Plant
life under changing environment. Elsevier, Amsterdam, pp 25–45
Tsiavos T, Ioannidis NE, Kotzabasis K (2012) Polyamines induce aggregation of LHC II and
quenching of fluorescence in vitro. Biochim Biophys Acta 1817(5):735–743
Verbruggen N, Hermans C (2008) Proline accumulation in plants: a review. Amino Acids 35:753–
759
Wang X, Li W, Li M, Welti R (2006) Profiling lipid changes in plant response to low temperatures.
Physiol Plant 126(1):90–96
Welti R, Li W, Li M, Sang Y, Biesiada H, Zhou HE et al (2002) Profiling membrane lipids in plant
stress responses: role of phospholipase Dα in freezing-induced lipid changes in Arabidopsis.J
Biol Chem 277(35):31994–32002
Xu T, Niu J, Jiang Z (2022) Sensing mechanisms: calcium signaling mediated abiotic stress in
plants. Front Plant Sci 13:13
Xue-Xuan X, Hong-Bo S, Yuan-Yuan M, Gang X, Jun-Na S, Dong-Gang G et al (2010) Biotech-
nological implications from abscisic acid (ABA) roles in cold stress and leaf senescence as an
important signal for improving plant sustainable survival under abiotic-stressed conditions. Crit
Rev Biotechnol 30(3):222–230
Yadav SK (2010) Cold stress tolerance mechanisms in plants. A review. Agron Sustain Dev 30(3):
515–527
Yamaguchi-Shinozaki K, Shinozaki K (1993) Characterization of the expression of a desiccation-
responsive rd29 gene of Arabidopsis thaliana and analysis of its promoter in transgenic plants.
Mol Gen Genet MGG 236:331–340
Yoshida T, Fujita Y, Sayama H, Kidokoro S, Maruyama K, Mizoi J et al (2010) AREB1, AREB2,
and ABF3 are master transcription factors that cooperatively regulate ABRE-dependent ABA
signaling involved in drought stress tolerance and require ABA for full activation. Plant J 61(4):
672–685
Zeng X, Ling H, Yang J, Li Y, Guo S (2018) LEA proteins from Gastrodia elata enhance tolerance
to low temperature stress in Escherichia coli. Gene 646:136–142
Zhao J, Davis LC, Verpoorte R (2005) Elicitor signal transduction leading to production of plant
secondary metabolites. Biotechnol Adv 23(4):283–333
https://t.me/medicina_free
193
Aquaporins Gene Expression in Plants
Under Stress Condition
12
Aradhana Mishra, Preksha Jaiswal, Akhileshwar Kumar Srivastava,
and Divya Singh
Abstract
Aquaporins (AQPs) are channel proteins associated with the major intrinsic
protein (MIP) superfamily which play a major function in plant water relations.
The crucial function of aquaporins in plants is transportation of water and other
neutral molecules over cellular membranes. AQPs have important properties to
aid in water flow and facilitate them for water movement into and out of the cells.
Therefore, the management of AQPs’ function and gene expression direct the
adaptation events under stress conditions and believe in intricated methods and
signaling events as well as complex transcriptional, translational, and posttran-
scriptional factors. Gating of AQPs by several events like phosphorylation,
tetramerization, pH, cations, reactive oxygen species, phytohormones, and other
chemical agents might play a function in plant responses to stresses by regulating
the uptake and transportation of water in the plants. This section has deciphered
the response of aquaporins (AQP) protein in plants to water-deficient condition.
Keywords
Aquaporin · Stress condition · Gene expression · Arabidopsis
A. Mishra
Veer Bahadur Singh Purvanchal University, Jaunpur, India
P. Jaiswal
Babasaheb Bhimrao Ambedkar Central University, Lucknow, India
A. K. Srivastava
Department of Plant Cell Biotechnology, Central Food Technological Research Institute, Mysore,
India
D. Singh (
✉)
Department of Mulberry Physiology, Central Sericultural Research and Training Institute, Mysore,
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_12
https://t.me/medicina_free
194 A. Mishra et al.
12.1 Introduction
Water is the crucial universal solvent paramount for all the existing living organisms
in the world. The transportation of water is the crucial part for the organism to
accomplish its fundamental processes. In the 1920s the transport of water in the cells
and its subcellular compartments was assumed through the simple diffusion by the
biological membrane, while the transport of water occurs in a very slow manner
across the membrane for the physiological processes like in the regulation of the
stomatal aperture in plants and the secretory pathways in mammals. However, this
process requires the flow of large volume of water in a rapid and reversible manner.
The subcellular compartments of the same cells exhibit the different levels of
permeability of water which cannot be fulfilled by the simple diffusion (Afzal
et al.
2016). Koefoed-Johnsen and Ussing in 1953 have reported the transport of
water through the specialized pores rather than the simple diffusion and then later
agreed by Macey and Farmer in 1970. The CHIP28 in the 1980s is the highly
abundant channel-forming 28 kDa integral membrane protein extracted from the
human erythrocytes (Afzal et al.
2016). The molecular identity of the first channel-
forming water aquaporin 1 (AQP1) was characterized by Agre and coworkers in
1992 and investigated that the CHIP28 gene expression Xenopus oocytes tends to
increase in the permeability of the water (Preston et al.
1992). In 1987 Nodulin-26
and GmNOD26 have been identified as an aquaporin member in the soybean . The
presence of pertinacious pores has been observed in the membrane of the plant
before its discovery in the human being (Wayne et al. in 1990). The existence of the
plant water channels was not clearly understood until 1993 as the first time the
aquaporin functionality has been demonstrated. (AtTIP1;1) is the homologue of
Arabidopsis tonoplast intrinsic protein in Xenopus laevis oocyte (Afzal et al.
2016).
Recently in 2015 it has been reported that the aquaporin is permeable not only to
water but also for the urea, NH
3
, glycerol, CO
2
, reactive oxygen species, and the
metalloids (Maurel et al. 2015). Due to immobile nature and absence of the circula-
tory system plants, aquaporin exhibits the greater requirement for the regulation of
the water to adapt the fluctuation in the environment.
Currently there are several genes encoding aquaporin that have been identified:
35 genes in Arabidopsis thaliana and 33 in rice, 31 in maize, 55 in Populus
trichocarpa, 71 in cotton, 50 in banana, and 41 in sorghum (Afzal et al.
2016).
The major role of aquaporin is to regulate the transport of water flow in the region
where the water flow regulation needs to be maintained or the water flow is critically
low (Luu and Maurel
2005). Generally, aquaporins are present in most organs of the
plant like root, stem, leaves, seeds, flowers, and fruits (Clarkson et al. 2000). The
hydraulic conductivity of the plant can be partially controlled by the aquap orins
activity especially like PIP2 (Javot et al. 2003). The abundance of the aquaporins and
changing the rate of water flow can control the water flow across the cell membrane.
The aquaporins’ functionality can be enhanced by interplaying with physiological
and biochemical processes of the plant (Aharon et al. 2003).
Many studies have been done in the analysis of the physiological responses
especially the water and photosynthesis stress (Galmés et al.
2007). The water
https://t.me/medicina_free
stress for short intervals can be responsible for producing the negative impact on
physiological activities of plants such as the growth, photosynthesis, and reduction
in water content (Chaves et al. 2003), while, in the field condition, the negative
impact can be rehandled by rewatering (Flexas et al.
2002). The acclimation to the
water stress leads to the reduction of negative impact at the initial time due to the
modification in the gene expression which also changes the morphology and physi-
ology of the plant. The acclimated plants have improved relationship with water
which leads to the lesser effect on the plant growth (Flexas et al.
2006). The
physiological mechanism in the acclimation is the accumulation of the solute as
well as the upregulation and downregulation of the specific proteins (Chaves and
Oliveira
2004); these responses are generally when the plant growth is ceased due to
the water stress; however, the mechanism of acclimation is still unknown. The
maintenance of the hydraulic conductivity can be crucial for the acclimation (Sperry
et al. 2002).
12 Aquaporins Gene Expression in Plants Under Stress Condition 195
Reddy et al. (2022) reported that
the gene expression in plants due to water stress
directly affects the transport of water and indirectly influences on other related
function.
The overexpression of the StPIP1 gene leads to the drought tolerance ability in the
potato where it has improved the water efficiency as well as the increased biomass
yielding, minimizing the starvation of the carbon, and increasing the nonstructural
carbohydrate elements (Wang et al. 2017).
In the transgenic banana, multiple abiotic stress tolerances have been observed
due to the ectopic expression of MaPIP1;1 and MaPIP2;7 (Xu et al. 2020), while in
the transgenic rice, there is the overexpression of the OsPIP1;3 which promotes the
plant growth and the uptake of water (Liu et al.
2021). Reddy et al. (2022) reported
that the PePIP2;7 gene isolated from the bamboo conferred its abiotic stress toler-
ance activity in the Yeast and Arabidopsis. This chapter will cover the major roles of
the aquaporins in plants under stress condition .
12.2 Discovery of Aquaporin
Instead of applying several approaches to explore the protein that developed water
channels, the field had been substantially frozen in time for several years. All
conducted approaches to separate the protein from purified membranes of
erythrocytes of toad bladders and kidneys had been achieved with limited success;
however, certain reports came close (Benga et al. 1986), and others contributed
major knowledge like molecular size (about 30 kDa) (Van Hoek et al. 1991
). The
Agre group observed Rhesus factor proteins in red cell membranes and a consistent
“contaminating” band on their gels at approx. 28 kDa. Besides throwing this report,
they drilled further and more envisaged that this may be the greater breakthrough
after water channel in red cells. It had been separated and purified, and application of
antibodies also provided pieces of evidences in cells of kidney proximal tubules and
the thin descending limb of Henle—both have greater permeability to water. It was
suspected to be a water channel. The confirmation made by the Agre group infused
https://t.me/medicina_free
mRNA codes in this protein in an in vitro system, Xenopus oocytes. The oocyte
membrane is generally highly impermeable to water—the eggs have been dipped
into normal water and would crack if the membrane revealed permeability! After
infiltration of mRNA coding for the presumed water channel, oocytes dipped into
distilled water accomplished precisely that they ruptured, whereas control oocytes
remained perfect. The Agre group noticed that the administered mRNA had enf
orced
the oocytes to form a new protein which, since it is located to the oocyte membrane
by cellular movement events, which resulted to membrane becoming highly perme-
able to water. This new protein, named CHIP28 (channel-forming integral mem-
brane protein of 28 kD), was explored as the first water channel (Brown
2017).
196 A. Mishra et al.
12.3 Stress Response of Aquaporins
Several reports explained that the maximum AQPs are controlled by several devel-
opmental and environmental components like biotic and abiotic stresses. Environ-
mental stresses like salinity, drought, and declined root temperature can speedily
decrease water transport rates (Javot and Maurel
2002; Siemens and Zwiazek 2003).
Apparently, the several alterations in environmental factors, maintaining water
balance under stress situation, could be a problematic and major challenge for plants
(Mahdieh et al. 2008). So, plants require to develop several adaptive factors to tackle
environmental stresses and their impact on water level. AQPs participate in
regulating water homeostasis and balance under distinct environmental stresses
(Ranganathan et al.
2017). The plethora of AQPs’ role in the plasma membrane is
governed to regulate water fluxes within the cells and intra- and intercellular
conditions.
Abiotic stresses like drought and salinity could change transmembrane water
flow. Alteration of AQP expression might be highly employed to govern water
movement under several abiotic stresses, although its effectiveness may diverge
based on the plant growth situation, phase of development, and tissue nature as well
as the periods and severity of stress (Javot and Maurel
2002; Alexandersson et al.
2005) and the kind of AQP (Jang et al. 2004
). While in abiotic stress, certain AQP
isoforms might be expressed in particular tissues, whereas other isoforms are
expressed all over the plants. The alteration of AQP gene expression has highly
supported to know plant water relations in stress conditions. Molecular assessments
of regulation of the complete AQP family have sometimes exhibited intricated
transcriptional and posttranslational responses, with sometimes reverse ways
between the distinguished isoforms, although the presence of AQP transcripts and
the encoded proteins are not significantly correlated (Almeida-Rodriguez et al.
2010). Indeed, all AQP transcripts are not translated into proteins due to the protein
turnover and posttranslational modifications (PTM). PTM is a stage of protein
synthesis thereby polypeptides go throu gh structural and functional alternations.
Turnover is the equity between the formation and deterioration of protein (Aroca
et al.
2005). The apparent function of AQPs in regulating plant water level under
distinct stress condition could not be precisely elucidated due to several AQP genes
https://t.me/medicina_free
which might be differently triggered or decreased or might remain unaltered under
abiotic stresses. In rice, the role of AQP was not rigorously correlated with root water
fluxes, though the role of AQPs became highly significant under drought conditions
(Grondin et al.
2016). Stress might also impact membrane trafficking of AQPs. In
Arabidopsis, salt stress was observed to stimulate the internalization of PIP2;1 from
the plasma membrane to the vacuolar cavity, and this event had been inhibited by
kinases and clathrin-mediated endocytosis (Ueda et al.
2016)
.
T
he provided stress
tolerance to tobacco by SpAQP1 gene from the halophytic plant Sesuvium
portulacastrum gives evidence for the value of AQPs in salt stress resistance
(Chang et al. 2016).
12 Aquaporins Gene Expression in Plants Under Stress Condition 197
12.4 Expression of Aquaporin Gene
Gene expression is a mechanism of transformation of gene information into proteins.
The first confirmation regarding the function of AQPs in plants was recorded from
the experimental data of their gene expression in several cells, tissues, and organs
upon exposure to various environmental factors. The presence of AQPs is crucial for
knowing their activity. Expression of AQPs might be changed by abiotic factors
such as drought, salinity, low temperatures, and wounding. AQP expression is also
influenced by phytohormones like abscisic acid and gibberellins (Hong et al.
2013).
Since PatPIP1 of Populus tremula × P. alba clone had been highly expressed in
response to salinity stress, it is supposed that expres sion of AQPs is a major event in
plant feedback to salt-induced water stress (Hong et al.
2013). Various methods are
employed for exploring and asses sing gene expression of protein channels in plants.
Generally, reverse transcription quantitative PCR (RT-PCR) technique is used for
determining the mRNA abundance, although it might be difficult since it necessitates
the correct design of experimental methods like specific and relevant primers (Bustin
et al.
2009). The RT-PCR is a very important technique which could be employed to
explore mRNA abundance for protein channels in medicinal plants.
The expression of gene is a stress response event whenever a gene is transcribed,
mRNA is converted into a protein, and the protein is rightly targeted. The manage-
ment of water transport via AQPs is intricate and has several processes and
components. MIP gene expression is controlled in a cell-specific way through
hormones and environmental components like water stress, pathogens, low temper-
ature, and salinity. MIP gene expression is also controlled by several signaling
pathways and via complex transcriptional, translational, and posttranscriptional
regulations, and it is cumbersome to differentiate a standard expression pattern for
every AQP gene (Hachez et al.
2006). In plants, regulation of AQP expression was
employed to analyze the role of protein in the osmotic water permeability and by
virtue of what the alterations of the expression of the same genes take measures.
Several reports explain that low expression of AQP proteins decreases the water
permeability and greater expression enhances the hydraulic conductivity of plant
membranes. AQP gene expression is also regulated via several mechanisms like
methylation, phosphorylation, and protonation. Such events have explained the
https://t.me/medicina_free
impact of AQP trafficking via the secretary mechanism to move the plasma mem-
brane causing to opening and closing of the pores. The AQP gene expression
patterns in distinguished plant species and certain tissues could also aid to explore
their activities under environmental stresses. Therefore, AQP gene expression plays
an important role in medicinal plants to handle different environmental stresses.
198 A. Mishra et al.
12.5 Aquaporin Expression in Response to Stress
Physiological reactions of plants to different abiotic stresses may be changed by the
genetic alterations of plants. Enhancing water use potential and plant water retention
in the cell is the major aim in the development of resistance to abiotic stresses. The
molecular events of regulation of AQP activity are also significant in plants
overexpressing AQP genes (Zhu et al.
2005). Expression of AQP-PIP1 of Vicia
faba (VfPIP1) in engineered Arabidopsis thaliana enhanced drought tolerance by
decreasing the transpiration rates via stomatal closure (Cui et al.
2008).
Overexpression of gene RWC3 causing relative water amount in engineered lowland
rice ( Oryza sativa) exhibited enhanced tolerance to polyethylene glycol (PEG)-
triggered osmotic stress via enhanced root hydraulic conductivity (Lian et al.
2004). The expression of OsPIP1;1 in rice was alleviated in leaves and decreased
in roots under salinity stress (Liu et al. 2013
). So, the reactions of all overexpressed
AQP isoform against a certain stress rely on the rise in water uptake from soil,
function of AQPs in the regulations of water depletion by transpiration, and its
potential to balance CO
2
assimilation. The impact of interaction of certain AQP
isoform on other endogenous AQPs might modify the response to stress. The
stomatal density and transpiration rates had been enhanced in engineered AtPIP1b-
overexpressing tobacco, while they were unaltered in transgenic NtAQP1-
overexpressing Arabidopsis in comparison to the wild-type plants. The alterations
in phenotype due to overexpression of AQP gene play major function in the
development of resistance in plants during abiotic stress (Cui et al.
2008
). Stress
resistance is gained by the participation of overexpressing foreign AQPs and the
endogenous AQPs. The expression of one AQP gene impacts the way of expression
and dissemination of endogenous AQP genes, and this impact differs across plant
species (Jang et al. 2007a
). The upregulation of cucumber (Cucumis sativus) AQP
genes CsPIP1;1 and CfPIP2;1 enhanced seed germination rate under salt stress. If the
root temperature (RT) had been decreased from 20 to 5 °C in solution culture for
30 min, PIP2:5 overexpressing hybrid aspen Populus tremula × alba (PtdPIP2;5ox)
AQP had greater net gas exchange rates and hydraulic conductivities (Lp) in com-
parison to wild-type plants, and recovery also was speedy in transgenic lines if the
RT was increased back to 2 0 °C (Ranganathan et al.
2016). If the plants were
provided low root temperatures for 3 weeks in liquid culture, gas exchange rates,
water use potential, and hydraulic conductivity of the transgenic lines had become
significantly greater in comparison to wild types but no alterations in relative plant
height growth and dry weight (Ranganathan et al.
2016).
https://t.me/medicina_free
12 Aquaporins Gene Expression in Plants Under Stress Condition 199
The expression of Cucurbita ficifolia AQP gene CfPIP2;1 enhanced the durability
rate of Arabidopsis plants under severe drought (Jang et al. 2007b). The activities of
PIP2 subfamily AQPs would be highly influenced in comparison to PIP1 subfamily,
under intense abiotic stress (Jang et al.
2007b). No exact mechanism is explored on
how the foreign AQP gene alters the activities of endogenous PIPs of Arabidopsis.
As explained above, overexpression of plant AQPs was not always involved in
enhancing tolerance ability to abiotic stress (Aharon et al.
2003; Perrone et al. 2012).
Overexpression of AQP gene AtPIP1b in Arabidopsis alleviated the growth rate, gas
exchange, and stomatal density in Nicotiana tabacum under supportive
environments but reduced the growth against drought conditions (Aharon et al.
2003). Hence, overexpression AQP gene plays an opposite role in certain plants
under stress conditions that may affect the metabolism pathway for production of
medicinally important compounds.
Aquaporins are necessary for controlling plant water relation and damage.
Richter-110 is a Vitis hybrid (Vitis berlandieri × rupestris) highly drought-tolerant
plant. Three irrigation treatments had been accomplished in Richter-110 plants
thriving outdoors explicated by the causing higher stomatal conductance (gs) and
providing water stress condition not adequate to check photosynthesis and growth:
well-watered plants (gs ~250 mmol H
2
Om
-2
s
-1
), modest water stress
(gs ~150 mmol H
2
Om
-2
s
-1
), and intense water stress (gs ~50 mmol H
2
Om
-
2
s
-1
). Plants under water stress condition had been subjected to consistent water
availability for 7 days to prevent plausible acclimation. Eventually, plants had been
rewatered and provided to restore, for 3 days. The relative quantities of expression of
mRNA encoding seven concoctive aquaporins had been analyzed in roots and leaves
by using RT-PCR. The declination of stomatal conductance with modest and
extreme water stress was based on rising xylem abscisic acid (ABA) levels, but
leaf water potential and hydraulic conductivities remained unaltered while experi-
mental work. The variation of aquaporin gene expression is based on certain
aquaporin, water stress condition, and the plant’s part. It has been suggested that
aquaporin expression was sensitive to water stress associated with the homeostasis
that maintained constant leaf water potential and hydraulic conductivity (Galmés
et al.
2007). So, aquaporin expressions are not always constant in plants which
depend on water stress level and the type of plant’s organs that could be similar in
medicinal plants.
Pearl millet (Pennisetum glaucum L.) is a crucial cereal crop of the semiarid
tropics that have potential to tolerate under prolonged drought and heat stress.
Instead of active participation of the AQP genes in water movement and drought
tolerance, their potential function in abiotic stress tolerance had been sequentially
explored and functionally approved. A total of 34 AQP genes in P. glaucum had
been explored and classified into four subfamilies such as plasma membrane intrin-
sic proteins (PIPs), tonoplast intrinsic proteins (TIPs), nodulin-26-like intrinsic
proteins (NIPs), and small basic intrinsic proteins (SIPs). Sequence assessment
exhibited that PgAQPs have conserved proper ties of AQP genes with a closer
linkage to sorghum. The PgAQPs had been expressed distinctively against high
vapor pressure deficit (VPD) and increasing drought stresses thereby the PgPIP2;6
https://t.me/medicina_free
gene revealed remarkable expression during alleviated VPD and drought stress. The
engineered tobacco plants had been made by heterologous expression of the
PgPIP2;6 gene and functionally explored under several abiotic stresses to understand
their function. Transgenic tobacco plants in the T2 generations revealed limited
transpiration and lower root exudation rates in low- and high-VPD situation. Under
increasing drought stress, wild-type (WT) plants revealed
a hasty or faster decrease
of soil moisture in comparison to transgenics. During heat stress condition, PgPIP2;6
transgenics adapted significantly to heat (40 °C) with greater canopy temperature
depression (CTD) and lower transpiration; under low-temperature stress, they
exhibited lower transpiration in comparison to their non-transgenic plants. Alto-
gether, lower transpiration rate (Tr), low root exudation rate, reduced transpiration,
alleviated CTD, and l
ower transpiration suggest that PgPIP2;6 involves in tolerance
of plants under abiotic stress condition. When PgPIP2;6 transgenic plants revealed
better adaptation under severe abiotic stresses like drought, high VPD, heat, and cold
by increasing transpiration potential, it has the ability to engineer abiotic stress
tolerance for endured growth and crop yield (Reddy et al.
2022). Hence, the
PgPIP2;6 as a novel gene could be transferred into medicinal plants by using
biotechnological approaches for sustained growth as well as metabolite production
under different stress conditions.
200 A. Mishra et al.
Melon (Cuc
umis melo L.), belonging to the Cucurbitaceae family, in Mediterra-
nean regions is generally impacted by abiotic stresses such as salinity, nutrient
depletion, and elevated temperature. Several genes are expressed in plants under
such different stresses. Of these genes, the AQP stand out because of their significant
role as transporters of water and several solutes. For unraveling the above cause,
work had been done on the expression levels of all (31) aquaporins of melon plants
(CmAQPs) after providing salt stress (50 mM NaCl) and nutrient-deficient (10%
Hoagland solution) condition or elevated temperature (40 °C for 1 h/day) and linking
them with nutrient level, water relations, and hydraulic conductance. It was com-
monly reduced in plant nutrient concentrations, mainly in the root (Fe, K, Mn, or
Zn), whereas the concentrations of certain elements for all stresses (B, Ca, Mg, Mo,
or Si) enhanced. Physiological aspects had been governed according to the treat-
ment, revealing the essential function of hydric physiology regulation in the com-
plete melon plant reaction to several stresses. The expression of maximum
aquaporins was reduced in the root (PIP2;1, PIP2;5, and PIP2;6 within the PIPs;
most of the TIPs; NIP6;1, NIP7;1; and SIP1;1) after all three treatments, whereas
other aquaporins were highly expressed like PIP1s (high-temperature treatment),
PIP2;2 (nutrient-deficient and elevated temperature), TIP1;1 (salinity and elevated
temperature), and NIP5;1 (nutrient-deficient). The expressions of aquaporins in leaf
were not much influenced. It has indicated that CmAQPs expression is altered
differently in response to different abiotic stresses associated with plant water
relations and nutrient concentration (Lopez-Zaplana et al. 2022). Like CmAQPs
expression, more AQP genes might be expressed in medicinal plants in distinct stress
conditions which need to be explored to unravel any mechanism related to metabo-
lite production.
https://t.me/medicina_free
12 Aquaporins Gene Expression in Plants Under Stress Condition 201
12.6 Integrated Functions of Aquaporins in Plant Stresses
Besides several experimental outcomes about the participation of aquaporins genes
in different stress conditions (Fig. 12.1), the exact functions of specific genes or
certain subfamilies are very difficult to explain due to their exceptionally complex
and synergistic functions in the response to distinct environmental factors and
participation in other plant growth and developmental events. Such integrated
involvement in several physiological parameters can be highly explained in trans-
genic plants having foreign aquaporin genes. The tolerance or susceptibility in
transgenic plants containing foreign aquaporin gene is cumulatively impacted by
interactions with other plant genes. The engineered Arabidopsis plants expressing a
Vicia faba PIP1 (VfPIP1) revealed the enhanced drought resistance because of
stimulation of stomatal closure to stop water loss in water-deficient situations (Cui
et al.
2008). Thus, the interaction of VfPIP1 with more genes and gene products
participated in stomatal movement helps to complete drought resistance. The sup-
pression of endogenous genes due to the expression of exogenou s aquaporins has
also been determined in the Raphanus sativus aquaporin RsPIP1;1 gene and is
expressed in eucalyptus leading to the suppression of endogenous EgPIP1 and
EgPIP2 PIP aquaporins (Tsuchihira et al. 2010). The overexpression of AtPIP1b
in tobacco led to enhanced stomatal density and elevated growth rates in supportive
conditions but substantial water loss under drought condition (Aharon et al.
2003).
The engineered tobacco plants overexpressing a wheat aquaporin TaAQP7 (PIP2)
gene revealed the enhanced function of detoxification enzymes causing increased
antioxidant defense and a decrease in H
2
O
2
contents under osmotic stress (Zhou
Fig. 12.1 Summary of plant aquaporins under different environmental stresses. Both PIPs and
TIPs are highly sensitive to drought, salt, and cold stresses which perturb cell osmotic balance. TIPs
along with NIPs are participated in biotic stress reactions and participated in controlling nutrient
balance between host and its pathogen. NIPs and TIPs also interplay with certain pathogen proteins
https://t.me/medicina_free
Соседние файлы в папке Библиотека им академика М.И. Перельмана