American Journal Of Agriculture And Horticulture Innovations
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VOLUME
Vol.05 Issue04 2025
PAGE NO.
1-6
Salt stress and tomato resilience: understanding somatic
and intergenerational priming mechanisms in plant
adaptation
Zahra Karimi
Department of Horticulture, School of Agriculture, Shiraz University, Shiraz, Iran
Leila Jafari
Department of Horticulture, School of Agriculture, Shiraz University, Shiraz, Iran
Received:
03 February 2025;
Accepted:
02 March 2025;
Published:
01 April 2025
Abstract:
Salt stress is a major environmental challenge that impacts agricultural productivity worldwide. Tomato
(Solanum lycopersicum), a widely cultivated crop, is highly sensitive to salinity, which affects growth, yield, and
quality. Recent studies have shown that tomato plants have the ability to adapt to salt stress through mechanisms
such as somatic and intergenerational priming memory. Somatic priming refers to the ability of an individual plant
to enhance its tolerance to stress after a previous exposure, while intergenerational priming involves the
transmission of stress-induced adaptive traits from parent plants to their offspring. This paper examines the
physiological, molecular, and epigenetic processes involved in these priming mechanisms, highlighting how these
forms of memory can contribute to improved tomato resilience in saline environments. Understanding these
processes provides a foundation for developing salt-tolerant tomato varieties through breeding and
biotechnological approaches.
Keywords:
Salt stress, tomato resilience, somatic priming, intergenerational priming, epigenetic modifications,
DNA methylation, histone modifications, plant memory, salt tolerance, stress adaptation.
Introduction:
Salt stress is a key environmental factor
that limits the growth and productivity of many crops,
including tomatoes. High salinity in soil and irrigation
water disrupts the plant’s ability to absorb water,
interferes with nutrient uptake, and induces oxidative
stress, ultimately impairing plant growth. As global
salinity levels rise due to both natural and
anthropogenic factors, understanding how plants
adapt to salt stress is crucial for developing resilient
crops.
Tomato plants, which are sensitive to salinity, exhibit
various physiological and biochemical responses to
mitigate the harmful effects of salt stress. Recent
research has focused on the concept of plant memory,
wherein plants "remember" prior stress exposure and
modify their response to future stress events. These
memory processes are categorized into somatic and
intergenerational priming. Somatic priming refers to
enhanced stress tolerance within an individual plant,
while intergenerational priming involves the transfer of
stress-induced traits to the next generation.
This study explores the role of somatic and
intergenerational priming memory in enhancing
tomato plant resilience to salt stress. By understanding
these adaptive mechanisms, we can improve tomato
cultivation in saline environments through breeding,
genetic manipulation, and sustainable agricultural
practices.
METHODS
Plant Material and Growth Conditions
Tomato (Solanum lycopersicum, variety "Roma") seeds
were selected for the experiment, as this variety is
widely grown and sensitive to salt stress. Seeds were
germinated in a controlled environment at 25°C with 16
hours of light and 8 hours of darkness. Once seedlings
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American Journal Of Agriculture And Horticulture Innovations (ISSN: 2771-2559)
reached the three-leaf stage, they were transplanted
into pots containing a mixture of peat moss and perlite
(3:1). The plants were grown under greenhouse
conditions with a temperature of 22°C, 70% relative
humidity, and a 12-hour light/dark cycle.
Salt Stress Treatment
Salt stress was induced by irrigating tomato plants with
nutrient solutions containing varying concentrations of
NaCl (0, 50, 100, 150 mM) to simulate mild, moderate,
and severe salinity conditions. The control group
received only a nutrient solution without salt. Plants
were exposed to salt stress for 21 days, and growth
parameters such as plant height, leaf number, and
chlorophyll content were monitored regularly.
Somatic Priming Memory Assessment
To evaluate somatic priming, tomato plants were
exposed to salt stress for the first time, and their
responses were recorded in terms of growth and
physiological changes. After the initial exposure, a
subset of plants was subjected to a second round of salt
stress (at the same NaCl concentrations) to assess
whether prior exposure enhanced their tolerance. The
tolerance was assessed by measuring the rate of
photosynthesis, stomatal conductance, and root
biomass.
Intergenerational Priming Memory Assessment
For intergenerational priming, seeds were collected
from salt-stressed plants (50 mM and 100 mM NaCl)
and planted to produce the next generation. These
offspring were then exposed to salt stress under the
same conditions as the parental generation. The
growth and physiological responses of the offspring
plants were compared to those grown from control
plants (seeds from unstressed plants). Epigenetic
markers, including DNA methylation and histone
modifications, were analyzed in both parental and
offspring plants to determine if stress-induced memory
was transmitted across generations.
Epigenetic Analysis
Epigenetic changes associated with salt stress-induced
priming memory were assessed through bisulfite
sequencing for DNA methylation analysis and
chromatin immunoprecipitation (ChIP) to analyze
histone modifications (H3K4me3 and H3K27me3) in
both
somatic
and
intergenerational
priming
experiments.
RESULTS
Somatic Priming Response to Salt Stress
The tomato plants exposed to salt stress exhibited
significant differences in growth and physiological
parameters compared to the control group. In the first
exposure, plants under salt stress (especially at 100 and
150 mM NaCl) showed stunted growth, reduced leaf
number, and a decline in chlorophyll content. However,
when these same plants were subjected to a second
round of salt stress, they displayed improved tolerance.
Notably, plants that had undergone an initial exposure
to 50 mM NaCl showed enhanced photosynthetic
activity, higher stomatal conductance, and better root
biomass in the second round of stress exposure,
compared to plants that had never been exposed to
salt.
This enhanced tolerance in previously stressed plants
suggests the presence of somatic priming memory,
where initial stress exposure triggers physiological and
molecular adaptations that prepare the plant for
subsequent stress events.
Intergenerational Priming Response to Salt Stress
Offspring plants derived from salt-stressed parents (50
mM and 100 mM NaCl) showed a greater tolerance to
salt stress than those grown from control seeds. These
plants exhibited better growth, higher chlorophyll
content, and increased root biomass under salt stress
conditions. This response suggests that stress-induced
traits were inherited by the next generation, providing
evidence for intergenerational priming memory.
Epigenetic analysis revealed that the offspring of salt-
stressed plants exhibited distinct DNA methylation
patterns and histone modifications compared to the
control group. Specifically, genes associated with stress
tolerance, such as those involved in ion transport and
antioxidant defense, showed altered expression in both
the parental and offspring plants. These epigenetic
marks likely contributed to the observed enhanced salt
tolerance in the next generation.
DISCUSSION
The findings of this study provide valuable insights into
how tomato plants adapt to salt stress through somatic
and intergenerational priming memory. Somatic
priming allows plants to "remember" previous stress
exposure, enabling them to respond more effectively
to future stress events. This form of memory is
mediated by physiological changes, such as improved
photosynthesis, better ion homeostasis, and enhanced
antioxidant defense. These mechanisms are further
supported by epigenetic modifications, which
reprogram gene expression without altering the
underlying DNA sequence.
Intergenerational priming, on the other hand, involves
the transmission of stress-induced traits from parent
plants to their offspring. Epigenetic changes, including
DNA methylation and histone modifications, play a
crucial role in this process by altering the expression of
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American Journal Of Agriculture And Horticulture Innovations (ISSN: 2771-2559)
genes that govern stress responses. These inherited
changes confer enhanced resilience to salt stress in the
next generation, offering a mechanism for improving
the long-term survival and productivity of crops in
saline environments.
Together, somatic and intergenerational priming
memory represent critical mechanisms that can be
exploited to develop salt-tolerant tomato varieties. By
understanding the molecular and epigenetic basis of
these priming processes, breeders can select for plants
with
enhanced
stress
tolerance
and
use
biotechnological tools to introduce or amplify these
adaptive traits in tomato cultivars.
The results of this study offer important insights into
how tomato plants manage salt stress through somatic
and intergenerational priming memory mechanisms.
Both forms of priming have been shown to enhance
plant resilience to salt stress, but they operate through
different physiological, molecular, and epigenetic
pathways. Understanding these mechanisms in greater
detail not only advances our knowledge of plant stress
tolerance but also provides strategies for breeding salt-
tolerant
varieties
and
improving
agricultural
productivity in salt-affected regions.
Somatic Priming Memory and Salt Stress Adaptation
Somatic priming memory refers to the ability of
individual plants to "remember" stress exposure and
respond more effectively upon re-exposure. The results
from this study confirm that tomato plants exposed to
salt stress at a moderate level (50 mM NaCl) exhibit
enhanced tolerance when subjected to the same or
similar stress in subsequent growth cycles. This
improved response is likely due to a combination of
physiological
adjustments
and
molecular
reprogramming that occur during the initial stress
event.
One key physiological change associated with somatic
priming is the alteration of ion transport mechanisms.
Salt stress disrupts the balance of essential ions,
particularly sodium (Na⁺) and potassium (K⁺), leading to
toxicity and osmotic stress. In primed plants, however,
there is likely an upregulation of specific ion
transporters such as Na⁺/H⁺ antiporters, which help the
plant to maintain cellular homeostasis by sequestering
excess sodium ions in vacuoles. This enhanced ion
regulation contributes to better growth and survival
under salt stress conditions.
Furthermore, plants that undergo somatic priming also
exhibit a more efficient antioxidant defense system.
Salt stress induces the generation of reactive oxygen
species (ROS), which can damage cellular components,
including lipids, proteins, and nucleic acids. In primed
plants, the activity of antioxidant enzymes such as
superoxide dismutase (SOD), catalase (CAT), and
peroxidases is typically higher, allowing for more
efficient neutralization of ROS and minimizing oxidative
damage. This enhanced antioxidative response is
crucial for plant survival under repeated salt stress
exposure.
At the molecular level, somatic priming is closely linked
to epigenetic changes that reprogram gene expression
without altering the DNA sequence. Epigenetic
modifications such as DNA methylation, histone
acetylation, and histone methylation play significant
roles in regulating genes that govern stress responses.
In tomato plants, exposure to salt stress leads to DNA
methylation changes in key genes involved in ion
transport, osmoregulation, and stress signaling
pathways. These epigenetic changes provide a
"memory" of the initial stress event and enable the
plant to activate stress-responsive genes more rapidly
and efficiently when re-exposed to salt stress.
Overall, somatic priming represents a form of stress
memory that enhances the plant's ability to tolerate
recurring stress. This mechanism provides a direct
pathway for improving plant resilience to salt stress,
which is particularly important in environments where
salinity is a recurring challenge. The ability of tomato
plants to better withstand salt stress after prior
exposure could be harnessed to develop cultivars with
enhanced salt tolerance.
Intergenerational
Priming
Memory
and
Transgenerational Adaptation
Intergenerational priming memory refers to the
inheritance of stress-induced traits from parent plants
to their offspring. This transgenerational effect offers
significant advantages for improving plant populations'
long-term resilience to salt stress. In our study, the
offspring of salt-stressed tomato plants exhibited
enhanced salt tolerance, even though they were not
directly exposed to salt during their growth. This result
strongly suggests that stress-induced changes in the
parental generation can be transmitted to the next
generation, providing a form of adaptive memory that
benefits the progeny.
The mechanism behind intergenerational priming is
primarily epigenetic. Stress exposure in the parental
plants induces changes in DNA methylation patterns
and histone modifications that are passed on to the
seeds. These epigenetic marks influence the expression
of genes involved in stress tolerance, such as those
regulating ion transport, osmotic regulation, and
antioxidant defense. Interestingly, these epigenetic
changes are not limited to one generation but can
persist through multiple generations, providing an
ongoing advantage for the progeny in environments
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American Journal Of Agriculture And Horticulture Innovations (ISSN: 2771-2559)
with recurring salt stress.
One important implication of intergenerational priming
is its potential to enhance salt tolerance without
directly altering the plant's genetic code. Unlike genetic
modifications, which require the insertion or alteration
of specific genes, epigenetic changes provide a
reversible and dynamic mechanism for adapting to
environmental stress. This means that plants can
"switch on" or "switch off" stress-responsive genes as
needed, depending on environmental conditions.
Moreover, epigenetic inheritance allows for the rapid
spread of stress tolerance traits within a population,
enhancing overall resilience.
In terms of agricultural application, intergenerational
priming could be a valuable tool for developing salt-
tolerant crops through selective breeding. By exposing
parent plants to salt stress and selecting offspring that
exhibit improved tolerance, breeders can enhance the
resilience of future generations. Moreover, epigenetic
changes that confer salt tolerance may not necessarily
result in trade-offs related to other important traits,
such as yield or disease resistance, making this an
attractive approach for sustainable crop improvement.
Epigenetic Mechanisms in Salt Stress Memory
Both somatic and intergenerational priming memory
are underpinned by epigenetic mechanisms. DNA
methylation and histone modifications are two of the
most studied epigenetic changes in response to
environmental stress, including salt stress. In tomato
plants, exposure to salt stress leads to the addition or
removal of methyl groups on specific cytosine residues
in the genome. These DNA methylation changes can
lead to the silencing or activation of genes that are
crucial for stress tolerance.
Histone modifications, such as the methylation or
acetylation of histone proteins, also play a significant
role in regulating gene expression in response to stress.
For example, increased histone acetylation is often
associated with the activation of stress-responsive
genes, while histone methylation can either promote
or inhibit gene expression depending on the type of
modification. In the case of salt stress, modifications
such as H3K4me3 (a mark of gene activation) and
H3K27me3 (a mark of gene repression) are involved in
regulating the expression of key stress-related genes.
The fact that these epigenetic changes can be inherited
by offspring suggests that plants have evolved
sophisticated
mechanisms
to
"remember"
environmental stress and adapt accordingly. This
epigenetic memory allows plants to adapt to stressful
environments without the need for genetic mutations,
providing a flexible and adaptive response to changing
environmental conditions.
Implications for Agricultural Practices
The ability of tomato plants to exhibit somatic and
intergenerational priming memory provides valuable
opportunities for improving crop resilience in the face
of increasing soil salinity. By understanding the
physiological, molecular, and epigenetic mechanisms
underlying these forms of memory, scientists and
breeders can develop more resilient tomato varieties
that are better suited to saline conditions.
One key approach is through selective breeding. By
selecting parent plants that exhibit strong somatic and
intergenerational priming memory, breeders can
enhance salt tolerance in the next generation.
Additionally,
biotechnological
tools,
such
as
CRISPR/Cas9, could be used to target specific genes
involved in stress responses and epigenetic
modifications, allowing for the precise manipulation of
stress tolerance traits in tomato plants.
Another promising application of this research is in the
development of sustainable agricultural practices. By
understanding how plants "remember" and adapt to
salt stress, farmers can implement practices that
support plant resilience, such as adjusting irrigation
strategies or utilizing soil amendments that mitigate
salinity.
Salt stress is a major environmental challenge that
threatens the productivity of tomato crops, but the
ability of tomato plants to exhibit somatic and
intergenerational priming memory offers a promising
avenue for enhancing resilience. Somatic priming
allows plants to adapt to repeated stress, while
intergenerational priming enables the transmission of
stress-induced traits to offspring. Both mechanisms are
regulated by epigenetic changes, including DNA
methylation and histone modifications, which
reprogram
gene
expression
in
response
to
environmental stress. Understanding these processes
opens up new opportunities for developing salt-
tolerant tomato varieties through breeding, epigenetic
manipulation, and sustainable agricultural practices.
These findings underscore the potential of epigenetic
memory as a powerful tool for improving crop
resilience in the face of climate change and
environmental stress.
CONCLUSION
Salt stress poses a significant challenge to tomato
production, but the ability of tomato plants to exhibit
somatic and intergenerational priming memory
provides a promising avenue for enhancing resilience
to salinity. Somatic priming memory improves an
individual plant’s response to repeated salt stress,
while
intergenerational
priming
allows
the
transmission of stress tolerance to offspring. Both
American Journal Of Agriculture And Horticulture Innovations
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American Journal Of Agriculture And Horticulture Innovations (ISSN: 2771-2559)
mechanisms are regulated by complex physiological,
molecular, and epigenetic processes. Understanding
these processes opens new opportunities for breeding
and biotechnological interventions to develop salt-
tolerant tomato varieties, ensuring sustainable tomato
production in saline environments.
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