Waterlogging stress in plants: A review

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DOI: 10.5897/AJARX11.084
Cite this publication
Waterlogging is the major obstacle for sustainable agriculture. Plants subjected to waterlogging suffer from substantial yield losses. Under natural environmental conditions, plants often get exposed to transient or permanent waterlogging. Flooding induces a number of alterations in important soil physio-chemical properties like soil pH, redox potential and oxygen level. Thus, the plants growing on the waterlogged soil face the stressful environment in terms of hypoxia (deficiency of O 2) or anoxia (absence of O 2). These oxygen deficient conditions substantially hamper plant growth, development and survival. Plants under O 2 -restrictive environment exhibit metabolic switch from aerobic respiration to anaerobic fermentation. It is evident from the available literature that most of the genes expressed under flooding stress are potentially involved in the synthesis of enzymes known to play active role in the establishment of this fermentative pathway. Plants undergo this metabolic change in order to get continuous supply of Adenosine triphosphate (ATP). Under waterlogged conditions, plants exhibit several responses including hampered stomata conductance, net CO 2 -assimilation rate and root hydraulic conductivity. Furthermore, plants grown under waterlogged conditions often face the oxidative damage induced by the generation of reactive oxygen species. These reactive oxygen species in turn affects the integrity of membranes and induce damage to the efficiency of photosystem II, thereby, causing considerable decrease in net photosynthetic rates. Moreover, these perturbations in physiological mechanisms may affect the carbohydrate reserves and translocations. In fact, waterlogging tolerant and sensitive plant species could be discriminated on the basis of their efficient carbohydrate utilization. Waterlogging is also known to induce adverse effects on several physiological and biochemical processes of plants by creating deficiency of essential nutrients like nitrogen, magnesium, potassium, calcium. Apart from these waterlogging-induced alterations in physiological mechanisms, plants growing under flooded conditions also exhibit certain morphological changes entailing the formation of adventitious roots, initiation of hypertrophied lenticels and/or establishment of aerenchyma. Therefore, the aim of this review is to highlight the major morphological, physiological and biochemical adaptations of plants to tolerate the flooding stress.
African Journal of Agricultural Research Vol. 7(13), pp. 1976-1981, 5 April, 2012
Available online at http://www.academicjournals.org/AJAR
DOI: 10.5897/AJARX11.084
ISSN 1991-637X © 2012 Academic Journals
Waterlogging stress in plants: A review
Muhammad Arslan Ashraf
Department of Botany, University of Agriculture, Faisalabad. E-mail: arsilpk@gmail.com. Tel: 041-9200161-67 ext. 3306.
Fax: 041-9200312.
Accepted 17 January, 2012
Waterlogging is the major obstacle for sustainable agriculture. Plants subjected to waterlogging suffer
from substantial yield losses. Under natural environmental conditions, plants often get exposed to
transient or permanent waterlogging. Flooding induces a number of alterations in important soil physio-
chemical properties like soil pH, redox potential and oxygen level. Thus, the plants growing on the
waterlogged soil face the stressful environment in terms of hypoxia (deficiency of O
) or anoxia
(absence of O
). These oxygen deficient conditions substantially hamper plant growth, development
and survival. Plants under O
-restrictive environment exhibit metabolic switch from aerobic respiration
to anaerobic fermentation. It is evident from the available literature that most of the genes expressed
under flooding stress are potentially involved in the synthesis of enzymes known to play active role in
the establishment of this fermentative pathway. Plants undergo this metabolic change in order to get
continuous supply of
Adenosine triphosphate (ATP). Under waterlogged conditions, plants exhibit
several responses including hampered stomata conductance, net CO
-assimilation rate and root
hydraulic conductivity. Furthermore, plants grown under waterlogged conditions often face the
oxidative damage induced by the generation of reactive oxygen species. These reactive oxygen species
in turn affects the integrity of membranes and induce damage to the efficiency of photosystem II,
thereby, causing considerable decrease in net photosynthetic rates. Moreover, these perturbations in
physiological mechanisms may affect the carbohydrate reserves and translocations. In fact,
waterlogging tolerant and sensitive plant species could be discriminated on the basis of their efficient
carbohydrate utilization. Waterlogging is also known to induce adverse effects on several physiological
and biochemical processes of plants by creating deficiency of essential nutrients like nitrogen,
magnesium, potassium, calcium. Apart from these waterlogging-induced alterations in physiological
mechanisms, plants growing under flooded conditions also exhibit certain morphological changes
entailing the formation of adventitious roots, initiation of hypertrophied lenticels and/or establishment
of aerenchyma. Therefore, the aim of this review is to highlight the major morphological, physiological
and biochemical adaptations of plants to tolerate the flooding stress.
Key words: Hypoxia, anoxia, fermentation, Adenosine triphosphate (ATP), reactive oxygen species (ROS),
In tropical and subtropical regions, excessive rainfall is
the major constraint for crop production. Elevated levels
of water in soil create hypoxic conditions (decrease in the
level of oxygen) within a short period of time. As a result
plant roots suffer from anoxia, complete absence of
oxygen (Gambrell and Patrick, 1978). However, plants
tolerant to waterlogging (flooding) stress exhibit certain
adaptations, for example, formation of aerenchyma and
adventitious roots. Furthermore, the formation of
adventitious roots is due to the interaction of plant
hormones, auxin and ethylene (McNamara and Mitchell,
1989). Oxygen deficiency inhibits the root respiration of
plants which results in substantial reduction in energy
status of root cells. Since oxygen is a terminal electron
acceptor in aerobic respiration, in its absence, Kreb’s
cycle and electron-transport system are blocked.
Therefore, plants under waterlogged conditions use
alternate pathway for energy extraction. This alternate
pathway uses fermentative metabolism to produce
Adenosine triphosphate (ATP), thereby, resulting in
enhanced accumulation of ethanol.
Moreover, the activity of alcohol dehydrogenase (ADH)
is also increased (Davies, 1980; Vartapetian, 1991).
In fermentation, plants could get only two ATP per
glucose molecule, whereas, 36 ATP molecules are
produced per glucose molecule in aerobic respiration.
Flood-tolerant plants are able to maintain their energy
status using fermentation. In addition, the maintenance of
cytosolic pH is of prime importance. In waterlogged
plants, initial decline in cytosolic pH has been observed
and this decline is attributed to the production of lactic
acid during fermentation. This initial decrease in pH helps
the plant to switch from lactate to ethanol fermentation by
activation of alcohol dehydrogenase and inhibition of
lactate dehydrogenase (Chang et al., 2000). As under
hypoxic or anoxic conditions oxygen is lacking, therefore,
alternative electron acceptor is required. For example,
nitrate has been considered as terminal electron acceptor
of plant mitochondria under anoxic or hypoxic conditions
(Vartapetien et al., 2003). It has also been suggested that
nitrate reduction is an alternate respiratory pathway and
is important for the maintenance and energy homeostasis
of the cell in the oxygen deficient environment
(Igamberdiev and Hill, 2004).
One of the first plant responses to waterlogging is the
reduction in stomata conductance (Folzer et al., 2006).
Plants exposed to flooding stress exhibit increased
stomata resistance as well as, limited water uptake
leading to internal water deficit (Parent et al., 2008). In
addition, low levels of O
may decrease hydraulic
conductivity due to hampered root permeability (Else et
al., 2001). Oxygen deficiency generally leads to the
substantial decline in net photosynthetic rate (Ashraf et
al., 2011).
This decrease in transpiration and
photosynthesis is attributed to stomata closure (Ashraf
and Arfan, 2005). However, other factors such as
reduced chlorophyll contents, leaf senescence and
reduced leaf area are also held responsible for
decreased rates of photosynthesis (Malik et al., 2001). In
this context, Yordanova et al. (2005) reported fast
stomata closure in barley plants when subjected to
flooding conditions. Similarly, when pea plants were
subjected to flooding conditions, a prompt closure of
stomata was recorded (Zang and Zang, 1994). This
stomata closure of pea plants was attributed to the
abscisic acid (ABA) transport from older to younger
leaves or denovo synthesis of this hormone.
Furthermore, prolonged exposure of plants to flooding
conditions could result in root injuries which in turn
restrict photosynthetic capacity
inducing certain
alterations in biochemical reactions of photosynthesis.
These biochemical alterations include restricted activity of
Ashraf 1977
ribulose bisphosphate carboxylase (RuBPC),
phosphoglycollate and glycollate oxidase (Yordanova and
Popova, 2001), demolition of chloroplast membrane
inhibiting photosynthetic electron transport and efficiency
of photosystem II (Titarenko, 2000). It is evident from the
literature that flooding causes a marked reduction in
photosynthetic capacity of a number of plants, for
example, Lolium perenne (McFarlane et al., 2003),
Lycopersicon esculentum (Bradford, 1983; Jackson,
1990) Pisum sativum (Jackson and Kowalewska, 1983,
Zhang and Davies, 1987), and Triticum aestivum
(Trought and Drew, 1980). However, plants exhibit
certain adaptation under waterlogging stress to maintain
photosynthetic capacity (Li et al., 2004). Moreover, flood-
induced destruction of chlorophyll has been investigated
widely by a number of researchers (Jackson et al., 1991;
Huang et al., 1994; Ashraf et al., 2011). This decrease in
chlorophyll directly or indirectly affects the photosynthetic
capacity of plants under waterlogged conditions (Ashraf
et al., 2011).
The adverse effects of waterlogging on different gas
exchange attributes of plants have been reported in some
earlier studies. For example, Ashraf and Arfan (2005)
reported decrease in photosynthetic rate, water use
efficiency and intrinsic water use efficiency of 32-day okra
plants when subjected to waterlogged conditions. It is a
general consensus that stomata regulation controls the
exchange rate of plants under waterlogged
conditions (Ashraf and Arfan, 2005; Ashraf et al., 2011).
Furthermore, water potential of plants is also controlled to
some extent by stomata regulations (Liao and Lin, 1996).
However, there are contrasting reports on the
involvement of stomatal regulation in maintenance of
water potential. For example, waterlogging caused a
marked reduction in stomata conductance of bitter melon.
This reduction in g
resulted in increased leaf water
potential (Liao and Lin, 1994). In contrast, Ashraf and
Arfan (2005) found no significant correlation between
stomata conductance and water potential of okra plants
under waterlogged conditions. In fact, these authors were
of the view that osmotic potential and pressure potential
are the main factors that determine water potential.
Waterlogging stress is also known to cause marked
perturbation in different chlorophyll fluorescence
attributes of plants. Since chlorophyll fluorescence is an
excellent physiological marker that determine the primary
processes involved in photosynthesis such as energy
transfer due to excitation, absorption of light and
photochemical reactions occurring in the PSII
(photosystem II) (DeEll et al., 1999; Saleem et al., 2011).
Therefore, changes in chlorophyll fluorescence
parameters determine the function and stability of
photosystem II (Jimenez et al., 1997; Abdeshahian et al.,
2010). The plants subjected to waterlogged conditions
exhibit certain alterations in this physiological marker. For
example, when Cork oak (Quercus variabilis) and China
wingnut (Pterocarya stenoptera) were subjected to
1978 Afr. J. Agric. Res.
waterlogging stress, a prominent decrease in maximum
quantum efficiency (Fv/Fm) was recorded (Hua et al.,
2006). Likewise, decrease in the maximum quantum yield
of PS II photochemistry (Fv/Fm) was also recorded in
flied beans when subjected to varying days of
waterlogging stress (Pociecha et al., 2008). PSII
photochemistry was also impaired due to waterlogging in
Medicago sativa. The decrease in Fv/Fm indicated the
sensitivity of photosynthetic apparatus to abiotic stress
and also inability of the plants to regenerate rubisco
under stressful conditions (Smethurst et al., 2005).
Despite the fact that oxygen is important for life on earth,
its reduction by any means could result in the production
of ROS perturbing several cellular metabolic processes of
plants (Ashraf, 2009; Ashraf et al., 2010). Lethal reactive
oxygen species include superoxide (O
), hydrogen
peroxide (H
) and the hydroxyl radical (OH). Singlet
oxygen generated due to the reaction of oxygen with
excited chlorophyll, is also considered as potential ROS
(Ashraf and Akram, 2009). These ROS are extremely
reactive in nature and induce damage to a number of
cellular molecules and metabolites such as proteins,
lipids, pigments, DNA etc (Ashraf, 2009). ROS are also
produced in plants under normal conditions or non-
stressed conditions but their concentration is very low.
However, when plants are facing some environmental
stress like waterlogging stress, the concentration of ROS
is elevated to a level that is damaging for several cellular
metabolic reactions of plants such as photosynthesis,
efficiency of PS II (Ashraf, 2009). For example, elevated
cellular levels of hydrogen peroxide result in inhibition of
calvin cycle (Ashraf and Akram, 2009).
ROS are free radicals possessing one or more
unpaired electrons. This is not a stable configuration;
therefore, the radicals react with other cellular molecules
to produce more free radicals (Foyer and Halliwell, 1976;
Hideg, 1997). Generation of reactive oxygen species
occurs via different mechanisms, for example, when
molecules of aerobic system come in contact with the
ionizing radiations, this interaction results in the
production of ROS. It is now a well established fact that
electrons flowing through electron transport chain may
leak from their proper rout and in the absence of any
electron acceptor, these electrons react with oxygen to
produce reactive oxygen species (Ashraf, 2009). Different
celluar organelles such as mitochondria, chloroplasts and
peroxisomes are considered as the sites for production of
reactive oxygen species (Sairam and Srivastva, 2002).
All the plants have the ability to detoxify the adverse
effects of ROS by producing different types of
antioxidants. Generally, antioxidants are categorized into
enzymatic and non-enzymatic antioxidants. Enzymatic
antioxidants include ascorbate peroxidase (APX),
superoxide dismutase (SOD), peroxidase (POD),
catalase (CAT), glutathione reductase (GR), whereas,
ascorbic acid, glutathione, tocopherols and carotenoids
are included in non-enzymatic antioxidants (Gupta et al.,
A marked alteration in the endogenous levels of
different enzymatic and non-enzymatic antioxidants has
been recorded in a number of studies. For example,
when mungbean plants were subjected to waterlogging
stress, the activities of various enzymatic antioxidants
such as glutathione reducatse (GR), superoxide
dismutase (SOD), catalase (CAT), and ascorbate
peroxidase (APX) decreased markedly (Ahmed et al.,
2002). These authors also stated that oxidative damage
was not directly involved in the impairment of
photosynthetic machinery of plants under waterlogged
conditions. Likewise, waterlogging-induced reduction in
the activity of one of oxygen processing enzyme SOD
has also been reported in corn (Yan et al., 1996). In
contrast, increase in the activities of different enzymatic
antioxidants was recorded in maize seedlings when
subjected to varying degree of waterlogging stress (Tang
et al., 2010). Similarly, when pigeon pea genotypes were
exposed to waterlogging stress, the activities of
superoxide dismutase (SOD), catalase (CAT), peroxidase
(POD) and ascorbate peroxidase (APX) increased
markedly (Kumutha et al., 2009). From these reports, it
is amply clear that plants when exposed to waterlogged
conditions employ antioxidant defense system to get
through the damaging effects of oxidative stress induced
by ROS.
Waterlogging reduces the endogenous levels of nutrient
in different parts of plants (Ashraf et al., 2011). Oxygen
deficiency in the root zone causes a marked decline in
the selectivity of K
uptake and impedes the transport
of K
to the shoots (Armstrong and Drew, 2002). It has
also been reported in the literature that hypoxic
conditions cause decrease in the permeability of root
membranes to Na
(Barrett-Lennard et al., 1999).
Generally, waterlogging causes acute deficiencies of
essential nutrients such as nitrogen, phosphorous,
potassium, magnesium and calcium (Smethurst et al.,
2005). In this context, Boem et al. (1996) reported a
marked decline in the uptake of N, P, K and Ca in canola
when exposed to short period of waterlogging stress.
Likewise, reduced endogenous levels of N, P and K have
been reported in maize (Atwell and Steer, 1990). When
M. sativa was subjected to flooding stress, a marked
reduction in leaf and root nutrient composition (P, K, Ca,
Mg, B, Cu and Zn) was recorded in plants (Smethurst et
al., 2005). Similarly, Stieger and Feller (1994) reported
reduced concentrations of P, K and Mg in wheat shoots
due to waterlogging. In contrast, the endogenous levels
of calcium remained unaffected in wheat under
waterlogged conditions. However, decrease in calcium
contents along with other nutrients (N, P, K and Mg) were
also recorded in different organs of wheat under
waterlogged conditions (Sharma and Swarup, 1989).
Similarly, Tarekegne et al. (2000) recorded a marked
reduction in Cu, Zn, P and K uptake in waterlogging
susceptible wheat genotype when compared with the
tolerant genotypes. These researchers were of the view
that genotypes that possess the ability to avoid
waterlogging-induced nutrient deficiency, particularly Zn
and P deficiency should be selected. Moreover, the
hampered efficiency of PS II is attributed to the
deficiencies of N, P, K, Mg and Ca (Smethurst et al.,
2005). It is evident from the literature that adverse effects
of waterlogging are not due to the toxic levels of Na and
Fe but reduced concentrations of N, P, K, Ca and Mg are
the major contributors (Sharma and Swarup, 1989;
Smethurst et al., 2005).
Waterlogging stress is also known to cause a number of
morphological and anatomical changes in plants. For
example, the presence of hypertrophied lenticels is a
common anatomical change observed in different woody
species under flooding stress (Yamamoto et al., 1995).
Radical cell division and expansion near stem base
results in hypertrophic growth. In addition, it is also
believed to be associated with ethylene and auxin
production (Kozlowski, 1997). The lenticels are thought to
be involved in the downward diffusion of O
as well as,
the compounds produced as by-products of anaerobic
metabolism (ethanol, CO
and CH
). Although, the actual
physiological role of lenticels is still unclear, their
presence is often linked to waterlogging tolerance in
plants (Parelle et al., 2006). Moreover, the number of
hypertrophied lenticels is more under the water surface
that supports the argument stating their involvement in
maintenance of plant water homeostasis and deviating
from the argument that dictates their role as important
facilitators of oxygen entry toward the root system. Their
potential role in the plant water homeostasis is evident
from their active involvement in partially replacing the
decaying roots and facilitating water intake for the shoot
(Parent et al., 2008).
Formation of adventitious roots potentially replacing the
basal roots is considered as one of the potential
morphological adaptations depicted by plants under
waterlogging stress (Malik et al., 2001). These
specialized roots maintain the continuous supply of water
and minerals when the basal root system fails to do so
Ashraf 1979
(Mergemann and Sauter, 2008). Furthermore, the
deterioration of the main root system is taken as the
sacrifice providing energy for the development of well
adapted root system (Dat et al., 2006). In addition, the
formation of adventitious roots is associated with
waterlogging tolerance of plants (Steffens et al., 2006).
Another important morphological response of plant is
the development of lacunae gas spaces (aerenchyma) in
the root cortex. The formation of aerenchyma is
considered as an adaptive response of the plant under
flooding stress (Evans, 2004). There are two types of
processes involved in the development of aerenchyma.
The first is constitutive development of aerenchyma as it
is not linked with the abiotic stress. It is formed by the
cells separated during tissue development. This type of
cell death occurring as a result of cell separation is
termed as shizogeny, regulated developmentally and
independent of external stimulus. It is formed as a result
of highly regulated tissue specific pattern of cell
separation. The second type of aerenchyma development
is known as Isogeny since it is formed due to partial
breakdown of the cortex that resembles programmed cell
death and its formation depends on the external stimulus
like abiotic stress (Pellinen et al., 1999).
Plants under waterlogged conditions exhibit marked up
and/or down-regulation of a number of genes. By
investigating the induced expression of these genes in
low oxygen environment, it is possible to identify certain
gene products. Then these potential genes involved in
conferring waterlogging tolerance can be isolated and
introduced into the transgenic plants in order to identify
their possible contribution in stress tolerance. Early
studies performed by isotopic labeling of maize roots with
S-methionine clearly indicated the synthesis of
anaerobic polypeptides when plants were subjected to
low oxygen environment (Sachs et al., 1980). The
anaerobic polypeptides include the enzymes involved in
fermentation, that is, pyruvate decarboxylate, alcohol
dehydrogenase and lactate dehydrogenase.
Moreover, there exists a marked variation in genetic
resources of potential crops for flooding tolerance. For
example, it has been widely reported in the literature that
genetic differences exists in wheat for waterlogging
tolerance (Gradner and Flood, 1993; Ding and Musgrave,
1995). Setter et al. (1999) showed that there exists a
significant genetic diversity among 14 wheat varieties
when exposed to flooding stress under glasshouse
conditions. Similarly, genetic variation has also been
reported in many other plant species, for example, oat
(Lemons e Silva et al., 2003), cucumber (Yeboah et al.,
2008), Soybean (VanToai et al., 1994) and maize(Anjus e
Silva et al., 2005).
1980 Afr. J. Agric. Res.
Scientists from different geographical regions of the world
are actively involved in making the plants tolerant to
flooding stress by the use of exogenous application of
nutrient and plant hormones. For example, recently,
Ashraf et al. (2011) reported that exogenous application
of potassium in soil and as foliar spray alleviated the
adverse effects of waterlogging on cotton plants.
Likewise, Ashraf and Rehman (1999) reported that
application of nitrate in soil proved useful in mitigating the
harmful effects of waterlogging on different physiological
attributes of maize. Likewise, Yiu et al. (2009) found that
exogenous application of spermidine and spermine
provoked several biochemical and physiological
adaptations in onion when exposed to flooding stress. In
this context, exogenous application of uniconazole was
also helpful in circumventing the damaging effects of
waterlogging in wheat and oil seed rape plants (Webb
and Fletcher, 1996; Zhou et al., 1997). Therefore, the use
of these organic and inorganic compounds offers an
excellent platform for inducing tolerance to flooding
It can be inferred from the aforesaid discussion that
waterlogging is one of the major constraints for
sustainable agriculture. Its effects are evident on the
entire plant as well as, cellular levels. There is the need
to screen available germplasm for waterlogging tolerance
and use the genes responsible for inducing tolerance in
other potential crops so as to make them resistant as
well. Waterlogging causes deficiency of several essential
nutrients. Therefore, exogenous application of these
nutrient or other plant hormones could be used so as to
alleviate the adverse effects of waterlogging.
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  • ... As the intensity of rainfall and evaporation increases due to global warming, many arid areas become even more arid, while many wetlands (mainly rural areas) are subjected to more frequent floods (Voesenek and Sasidharan 2013). It has been estimated that, annually, more than 17 million km 2 are exposed to flooding (Voesenek and Sasidharan 2013) which is especially concerning for plant crop productivity in tropical and sub-tropical regions (Ashraf 2012, Pedersen et al. 2017. ...
    ... All rights reserved. a decrease in gas diffusion in water of around 10 4 times (Bailey-Serres et al. 2012), which rapidly generates a hypoxic environment in roots proximity (Ashraf, 2012). ...
    ... Although little is known about the causes of photosynthesis decline in flooded plants, most plants undergo a drop in carbon assimilation rate when exposed to such stress (Yordanova and Popova 2007, Herrera et al. 2008, Bhatt et al. 2015Mutava et al. 2015, Najeeb et al. 2015. It is believed that stomatal closure, decrease of mesophyll CO2 conductance, chlorophyll loss, reduction of carboxylation activity and oxidative damage of photosystem II (PSII) reaction centres impair CO2 uptake capacity in flooded plants (Ashraf 2012, Striker 2012, Pompeiano et al. 2019. In general, while a stomatal limitation could account for the initial reduction in carbon assimilation, a non-stomatal limitation takes place after longer periods from the onset of flooding stress due to the alteration of some biochemical reactions involved in photosynthesis (Chen et al. 2015, Yordanova et al. 2005. ...
    Ethylene is considered one of the most important plant hormones orchestrating plant responses to flooding stress. However, ethylene may induce deleterious effects on plants, especially when produced at high rates in response to stress. In this paper, we explored the effect of attenuated ethylene sensitivity in the Never ripe (Nr ) mutant on leaf photosynthetic capacity of flooded tomato plants. We found out that reduced ethylene perception in Nr plants was associated with a more efficient photochemical and non‐photochemical radiative energy dissipation capability, in response to flooding. The data correlated with retention of chlorophyll and carotenoids content in flooded Nr leaves. Moreover, leaf area and specific leaf area were higher in Nr , indicating that ethylene would exert a negative role in leaf growth and expansion under flooded conditions. Although stomatal conductance was hampered in flooded Nr plants, carboxylation activity was not affected by flooding in the mutant, suggesting that ethylene is responsible for inducing non‐stomatal limitations to photosynthetic CO2 uptake. Upregulation of several cysteine protease genes and high protease activity led to Rubisco protein loss in response to ethylene under flooding. Reduction of Rubisco content would, at least in part, account for the reduction of its carboxylation efficiency in response to ethylene in flooded plants. Therefore, besides its role as a trigger of many adaptive responses, perception of ethylene entails limitations in light and dark photosynthetic reactions by speeding up senescence process that leads to a progressive disassembly of the photosynthetic machinery in leaves of flooded tomato plants. This article is protected by copyright. All rights reserved.
  • ... Flooding is a major factor, limiting growth and production of plants on a global scale [1]. Agricultural development is hindered by flooding every year in many countries and regions around the world. ...
    ... In response to stress, oxidoreductase activity in the GO enrichment term was significantly enriched at both time points, and it was also significantly up-regulated in the GO enrichment entry in cucumber exposed to flooding stress [16]. At 8 h and 24 h of stress, the differential genes were significantly expressed in the two GO terms entries of oxidation-reduction process and oxidoreductase activity, indicating that different groups of oxidoreductase genes were involved in maintaining redox balance or alleviating sputum-induced oxidative stress [1] suggesting that oxidoreductase activity played an important role in plant response to flooding stress. In the study, in the GO enriched molecular function category, binding, catalytic activity and transporter activity were highly present, which was consistent with the analysis of the short-term smear stress on the rhizome transcriptome of Taxodium [19]. ...
    Full-text available
    Background: Orchardgrass (Dactylis glomerata L.) is a popular cool-season perennial grass with a high production value, and orchardgrass seed is the fourth top-selling forage grass seed in the world. However, its yield and quality are often affected by flooding. To date, the molecular responses of orchardgrass to flooding were poorly understood. Results: Here, we performed mRNA-seq to explore the transcriptomic responses of orchardgrass to a short term flooding (8 h and 24 h). There were 1454 and 565 differentially expressed genes identified in the 8 h and 24 h of flooding, respectively, compared to well control. GO functional enrichment analysis showed that oxidoreductase activity and oxidation-reduction process were highly present, suggesting that flooding induced the response to oxygen stress. Pathways enrichment analysis highlights the importance of glutathione metabolism, peroxidase, glycolysis and plant hormone signal transduction in response to flooding acclimation. Besides, the ROS clearance system is activated by significantly expressed glutathione S-transferase and genes encoding SOD and CAT (CAT1 and CDS2). The significant positive correlation between RNA sequencing data and a qPCR analysis indicated that the identified genes were credible. Conclusion: In the process of orchardgrass response to flooding stress, multiple differential genes and biological processes have participated in its acclimation to flooding, especially the biological processes involved in the removal of ROS. These results provide a basis for further research on the adaptation mechanism of orchardgrass to flood tolerance.
  • ... The strong decrease in the F v /F m ratio was especially evident in the plants with 9 d of waterlogging and 12 of recovery, with values below 0.7, which indicated severe stress that generated serious damage in PSII and showed, according to Ashraf (2012), the inability of the plants to regenerate Rubisco under these stressful conditions. In the other treatments, with levels that exceeded 0.7, the functioning of PSII was not impaired (Bansal et al., 2019); rather, there was a dynamic photoinhibition, without presenting real damage to the photosystems . ...
    Full-text available
    Climate change has resulted in an increasing frequency of the phenomenon “La Niña,” generating prolonged periods of waterlogging and low light. The objective of the present study was to evaluate the effects of two abiotic stresses: shading (65%) and waterlogging, and their interaction on fluorescence parameters of chlorophyll a in lulo (Solanum quitoense var. septentrionale) seedlings. A completely randomized design with a factorial arrangement was implemented. The first factor consisted of two levels of light (with and without shading). The second factor were four levels of duration of the waterlogging period (0, 3, 6 and 9 days), for a total of 8 treatments with three replicates. The response variables were recorded at 6, 12 and 18 days after the application of the waterlogging treatments began. Measurements of relative water content (RWC), electrolyte leakage, chlorophyll content and chlorophyll a fluorescence were recorded. The lulo plants appeared to be more susceptible to waterlogging than to shading, with a lower RWC when waterlogged 6 and 9 days, presenting damage at the level of photosystem II from day 3, causing a decrease in the chlorophyll content. The plants flooded under shading had a greater tolerance to this factor than those cultivated in full light. The techniques of quantification of the chlorophyll a fluorescence, especially the maximum quantum efficiency of the PSII, the effective photochemical quantum yield of PS II and the photochemical quenching were useful tools that characterized the lulo seedlings under stress conditions.
  • ... Still, Kutschera and Briggs (2012) noticed distinct groups of cress reacting with positive, negative or no phototropism. However, these seedlings were grown in hydroculture, which constitutes a potentially detrimental flooding-like condition (Ashraf, 2012;Sauter, 2013). Indeed, Hubert and Funke (1937) had already rearranged their experimental setup after noticing such damaging effects of hydroculture on roots and found no differences in phototropic response of different cress individuals. ...
    Full-text available
    Root tropisms are important responses of plants, allowing them to adapt their growth direction. Research on plant tropisms is indispensable for future space programs that envisage plant-based life support systems for long-term missions and planet colonization. Root tropisms encompass responses toward or away from different environmental stimuli, with an underexplored level of mechanistic divergence. Research into signaling events that coordinate tropistic responses is complicated by the consistent coincidence of various environmental stimuli, often interacting via shared signaling mechanisms. On Earth the major determinant of root growth direction is the gravitational vector, acting through gravitropism and overruling most other tropistic responses to environmental stimuli. Critical advancements in the understanding of root tropisms have been achieved nullifying the gravitropic dominance with experiments performed in the microgravity environment. In this review, we summarize current knowledge on root tropisms to different environmental stimuli. We highlight that the term tropism must be used with care, because it can be easily confused with a change in root growth direction due to asymmetrical damage to the root, as can occur in apparent chemotropism, electrotropism, and magnetotropism. Clearly, the use of Arabidopsis thaliana as a model for tropism research contributed much to our understanding of the underlying regulatory processes and signaling events. However, pronounced differences in tropisms exist among species, and we argue that these should be further investigated to get a more comprehensive view of the signaling pathways and sensors. Finally, we point out that the Cholodny-Went theory of asymmetric auxin distribution remains to be the central and unifying tropistic mechanism after 100 years. Nevertheless, it becomes increasingly clear that the theory is not applicable to all root tropistic responses, and we propose further research to unravel commonalities and differences in the molecular and physiological processes orchestrating root tropisms.
  • ... Waterlogging, an abiotic stress, often results in anoxic respiration as its hypoxic conditions (Elzenga and van Veen, 2010;Tanaka et al., 2011). As a result, fruit crops grown in waterlogging have bad root hydraulic conductivity, stomatal aperture, photosynthetic capacity, and nutrient availability (Ashraf, 2012;Yin et al., 2012). Earlier studies indicated that AM citrus and peach plants presented greater plant growth performance and plant biomass than non-AM plants under waterlogging stress (Rutto et al., 2002;Wu et al., 2013;Zou et al., 2014). ...
  • ... Moreover, waterlogging is often associated with changes in plant metabolism to manage energy production and consumption (Pedersen et al. 2017). Waterlogging tolerant and non-tolerant trees can be differentiated by their efficiency to maintain their carbon metabolism (Parent et al. 2008;Ashraf et al. 2012;Delgado et al. 2018). While flooding-tolerant trees are able to maintain a steady supply of NSCs to roots to sustain fermentative rates and growth over time, sensitive trees fail to maintain sufficient NSC supply to roots (Parelle et al. 2006;Gérard et al. 2009;Ferner et al. 2012;Martínez-Alcántara et al. 2012;Kreuzwieser and Rennenberg 2014). ...
    Key message Two months of drought or waterlogging conditions did not induce carbon starvation in Castanea sativa. Carbohydrate dynamics in treated plants provide evidence of why this species adapts well to dry but not to waterlogging conditions. Abstract Drought and flooding events, which cause water and oxygen deprivation in tree roots, are expected to occur more frequently due to climate change. The effects of drought and waterlogging on physiology, growth and N content of Castanea sativa Mill. were explored. Through a manipulative experiment, we induced growth-limiting conditions in C. sativa seedlings to identify differences in the dynamics of soluble sugars, starch and total non-structural carbohydrates (NSC) in leaves, stems and roots. Two-year-old seedlings were subjected for 2 months to regular watering, drought and waterlogging treatments. Drought and waterlogging induced similar effects on plants, including reduced stomatal conductance, net photosynthesis and growth. However, chlorophyll degradation was detected only in plants subjected to waterlogging. N content and C/N ratios differed between treatments and were highest in leaves of drought stressed plants and roots of control plants, respectively. Under drought, starch was rapidly depleted to yield soluble sugars and afterwards remained constant, and no change in total NSC was observed, probably allowing plants to reverse drought-induced xylem embolisms. Under waterlogging, a net gain of NSC over time in plant stems and roots was observed, suggesting that plants were unable to utilise them. This is the first study to report different strategies of carbon use in C. sativa trees subjected to drought and waterlogging. NSC dynamics in C. sativa plants provide evidence of why this species adapts well to dry but not to waterlogging conditions.
  • ... Improper drainage and water logging lead to substantial yield lost due to alteration of soil physical-chemical properties like pH, redox potential and oxygen level. Such changes in the soil properties have been considered as a major obstacle for sustainable agriculture (Ashraf 2012). ...
    Sustainable food production is one of the major challenges in this era of global environmental problems such as population pressure, natural resource degradation, biodiversity loss and climate change. Agriculture being one of the prime sectors that sustain livelihood of the farmers also contributes to climate change. In this context, traditional agriculture has proven its effectiveness, adaptability and resilience for sustainable food production in the changing climatic conditions. The bun agricultural practice of the Khasi and Jaintia tribes of Meghalaya in Northeast India based on traditional ecological knowledge (TEK) offers an interesting example of sustainable agriculture and food production. An overview of the traditional bun cultivation practices and its modifications adopted by the local people has been discussed in the present study. The data for this study were obtained through focus group discussions with the cultivators and interviewing key informants followed by field survey. The study revealed that farmers grow the crops under a completely rain fed condition and make use of limited biomass and land resources, organic fertilizers and pesticides, thereby making the system sustainable. In addition, the farmers also abandon the land for a period of one to three years to restore soil fertility. However, due to increase in population, growing food demand, limited land availability and the socio-economic condition of the farmers, the traditional bun cultivation has undergone a number of modifications. The modifications include changes in cropping pattern, choice of crop, pest management and fallow period management that adapt well to local climatic conditions with higher food production and economic benefits. Understanding the various modifications and their integration with traditional agricultural practices can potentially form the basis for a sustainable, economically viable, environmentally sound and resilient agricultural system.
  • Article
    Major parts of agricultural lands in arid and semi-arid regions of India are affected by soil salinity and waterlogging in canal command area and outside. Waterlogging is caused by a rising water table and poor drainage conditions. Stress due to waterlogging and salinity are serious to plants in all stages from seed germination to active growth and maturity. Unmanaged affected agricultural lands turn into low productive marshlands in the long run. Physical provision of surface or sub-surface drainage structures can rescue in such a situation. Yet, high skill and investment are required in the installation and maintenance of such structures. Alternatively, biodrainage method has been evolved as an effective method recently world over. In biodrainage, plants are raised over a larger area, which can transpire and remove an enormous amount of water from the soil. Plants having adequate adaptive traits and tolerance mechanisms are desirable to mitigate waterlogging and salinity. Biodrainage is suitable in rainfed and irrigated conditions. Planting of right plant species in optimum population and geometry decides the efficiency of biodrainage. Further, combining biodrainage with the conventional drainage can improve land and water productivity. Eucalyptus is the most suitable tree species for biodrainage as it has well performed in versatile environments. It possesses appreciable tolerance to salinity, sodicity and waterlogged conditions of the soil. Fast-growing with a straight trunk, deep rooting ability, low shading effect and high transpiration capacity are promising characteristics of this tree. Prominent woody species like Acacia nilotica, Dalbergia sissoo, Hardwickia binata can also be grown for high profit.
  • Chapter
    Pigeonpea is the most important legume grown in semiarid tropics and generally grown in low-lying areas. In low-lying areas, the chances of waterlogging are maximum. Some pigeonpea varieties are sensitive but some are quite tolerant to waterlogging. The main cause of damage is suffocation which the plant has to face due to waterlogging. Oxygen deficiency causes electrolyte leakage due to which the cell is exposed to the outside environment which can also cause peroxidation of lipid and nucleic acid and ultimately death. So any mechanism that can reinstate oxygen supply to stressed tissue can be a major trait for waterlogging tolerance. Formation of aerenchyma, adventitious roots, and lenticels is helpful in restoring oxygen to waterlogged plants. Besides the formation of these, various types of biochemical changes also occur for waterlogging tolerance in pigeonpea plants. Biochemical changes include increase in reducing sugars, activity of enzymes used in glycolysis and fermentation, and participation of antioxidants. Glycolytic enzymes include alcohol dehydrogenase and sucrose synthase. The antioxidant system includes enzymatic and non-enzymatic antioxidants. Enzymatic antioxidants include superoxide dismutase, catalase peroxidase, ascorbate peroxidase, and glutathione peroxidase, while ascorbate and glutathione fall under the category of non-enzymatic antioxidant defense system. We emphasize the attributes responsible for waterlogging tolerance in pigeonpea.