Advance Journal of Food Science and Technology 4(6): 352-356, 2012
ISSN: 2042-4868; E-ISSN: 2042-4876
© Maxwell Scientific Organization, 2012
Submitted: August 31, 2012
Accepted: October 03, 2012
Published: December 20, 2012
Physiological Responses Differences of Different Genotype Sesames to Flooding Stress
1
1
Feng-ying Xu, 1Xiao-ling Wang, 1Qi-xia Wu, 2Xiu-rong Zhang and 2Lin-hai Wang
Department of Agronomy, Yangtze University, Jingzhou 434025, Hubei, P.R. China
2
Department of Oil Crops Research, Chinese Academy of Agricultural Sciences,
Wuhan 430062, Hubei, P.R. China
Abstract: The objective of this study was to elucidate the physiological reaction variation of different genotype
sesames to flooding stress. Different sesame genotypes, including two Water logging Tolerant Genotypes (WTGs),
WTG-2541 and WTG-2413 and one water logging sensitive genotype, WSG-EZhi2, were used as tested materials.
Flooding was applied for 48 h when plants were at the three-leaf stage before a number of parameters were assessed.
Characteristics that were detected included photosynthetic characteristics of seedlings, contents of proline and
Malondialdehyde (MDA), activities of Peroxidase (POD), Catalase (CAT) and Superoxide Dismutase (SOD).
Results showed the net photosynthetic rate (PN) of the three tested sesame seedlings all decreased. After a 15 days
restore growth under normal field conditions, the PN of WTGs was lower than control with no significant difference.
In contrast, the PN of WSG was lower than control significantly. In flooding, both the WTGs and WSG showed the
higher proline contents than that of control, however, a significant lower MDA contents were observed in seedlings
flooding treated than that of control. The POD activities of the WTGs increased rapidly while of the WSG decreased
with flooding stress. The opposite reaction was observed in activities of CAT, of which the WTGs showed a less
percentage decreasing than that of the WSG. The SOD activities of three tested materials increased in flooding, with
the WTGs increasing more than of the WSG. In general, the WTGs of sesames showed a substantial tolerance to
flooding stress by increasing organic osmoregulation content and activities of active oxygen scavenger enzymes.
Keywords: Antioxidant enzymes, flooding stress, net photosynthetic rate, physiological parameters, sesame
important aims for sesame breeding. Also, highly
resistant plants mingled with desired agronomical trails
will be the demand of future crops (Hohd et al., 2010).
Previously, some authors observed significant
genotypic differences among wheat cultivars in
response to flooding stress and suggested that traits
associated with flooding tolerance are simply inherited.
As an important economic crop, sesame has been
cultivated in the Jianghan plains of Hubei province over
2,000 years. However, studies on the inheritance of
water logging tolerance in sesame are also limited. In
this study, a traditional sesame cultivar (WSG-EZhi2)
and two newly cultivated sesame lines (WTG-2541 and
WTG-2413) were used to study the characteristics of
sesame under flooding stress by measuring their
photosynthetic characteristics, anti-oxidative enzymatic
activities and contents of proline and malnodialdehyde.
The study could provide theoretical basis for screening
of water logging resistant sesame species, expansion of
genetic resources and improvement of sesame yields.
INTRODUCTION
Poor soil aeration associated with excessive
moisture usually influences plants growth in a negative
way (Boru et al., 2001). In waterlogged soils carbon
dioxide, ethylene, manganese and iron may accumulate
in concentrations potentially toxic to plants. However,
oxygen deficiency is the most important cause of
flooding injury (Kozlowski, 1984).
In rainy and humid regions, sesame yield is limited
by waterlogged soils resulting from excessive rainfall.
In the Jianghan plains of Hubei province in China,
water logging commonly damages sesame during
seedling establishment. Water logging occurs
periodically in irrigated regions due to poor drainage.
Inadequate soil aeration affects photosynthesis and
activities of metabolizing enzymes. The degree of stress
on sesame in water logging soils depends on the crop
stage, duration of flooding, soil type, growth conditions
and genotype. Genotypic differences in response to
flooding have been reported in wheat and pepper and so
on. However, studies on the resistance ability of
different genotype sesames against water logging are
limited. Therefore, selecting water logging resistant
germplasms along with expanding genetic resources
and increasing genetic diversities is one of the most
MATERIALS AND METHODS
Materials: Two sesame lines tolerant to water logging
(WTG-2541 and WTG-2413) and one sensitive cultivar
(WSG-EZhi2) were included in the study. All of the
Corresponding Author: Xiao-ling Wang, Department of Agronomy, Yangtze University, Jingzhou 434025, Hubei, P.R.
China, Tel.: +86-716-8066899
352
Adv. J. Food Sci. Technol., 4(6): 352-356, 2012
three materials were provided by Oil Crops Research
Institute, Chinese Academy of Agricultural Sciences,
Wuhan, China.
Methods:
Experimental design: Three sesame genotypes,
including WTG-2541, WTG-2413 and WSG-EZhi2,
were used as tested materials. One field experiment was
conducted in practice base of Agricultural College,
Yangtze University and Jingzhou, China. The soil type
is classified as fine clay, medium fertility (8 mg/g
organic matter) with a pH of 8.7 in the plow-layer. Each
material was planted in a single basin of 3×5 m size in a
completely randomized design with three replications.
Seeds were planted with 40 cm row spacing and 20 cm
plant spacing on 1 June 2011. The basin’s outer ridges
were subsequently constructed with mound and
waterproof plastic to avoid leakage. Initial irrigation
was applied immediately to commence germination and
the excess water drained after 45 min. For flooding
treatment, one more flooding-irrigation was given at the
three-leaf stage when all basins were filled with water
to 0.5-1 cm above the soil surface. This level was
maintained for 48 h by replenishing the basins
frequently. Then the water was drained from the basins.
Subsequently, a 15 days restore growth under normal
field conditions was conducted. Physiological
parameters of seedling samples both before and after
the restore growth were assessed.
Indicators determination: Seedling samplings were
collected after drained 3 h to determine related
indicators.
Net photosynthetic rate (PN) was determined
between 09:00-11:00 h (Beijing time) at the three-leaf
stage using a portable photosynthesis system (LI-6400,
Li-COR, Inc., Lincoln, NE, USA) with a 3×2 cm
(length × width) leaf chamber with air humidity of
49.5±1.8%. The PN was measured at the irradiance of
1,000 μmol m2/s, temperature of 30.5±0.7°C and the
natural CO2 concentration.
Proline content and enzyme activity of Superoxide
Dismutase (SOD) were determined according to Ou
et al. (2011). Enzyme activity of Catalase (CAT) was
determined according to Hwang et al. (1999) by
measuring the rate of decomposition of H2O2 at 240
nm. Peroxidase (POD) activity was measured according
to literature (Zhang et al., 2007) by recording the
increase in absorbance due to oxidation of guaiacol.
Content of Malondiadehyde (MDA) was determined
according also to Zhang et al. (2007) to estimate the
lipid peroxidation.
Statistical analysis: Means and variance were
computed in Excell 2003 to compare parameters above
mentioned using the ANOVA of SAS Procedure. P
values less than 0.05 was considered as statistically
significant difference.
RESULTS
Effect of flooding stress on PN of sesame seedlings:
Under flooding stress, the Net Photosynthetic rates
(PN) of leaves for all tested sesame seedlings were
decreased significantly: WSG-EZhi2 had the biggest
decrease (decreased by 98.32%); WTG-2541 had the
second smallest decrease and WTG-2413 had the least
decrease (decreased by 59.23 and 55.15%,
respectively), indicating the two newly cultivated
sesame lines are less susceptible to flooding injury than
the former. The PN increased gradually three days after
restore growth (under normal field conditions). At 15
days after restore growth, PN of the WTG-2541 and
WTG-2413 increased greatly to 90.72 and 96.42%
compare to controls, respectively. In contrast, PN of
WSG-EZhi2 increased only to 71.71% (Table 1).
Effect of flooding stress on proline content: There
were no significant differences among proline contents
of all the tested materials before flooded with the values
of 15.10, 17.13 and 16.53 μg·g-1FW (FW: fresh weight)
for WTG-2541, WTG-2413 and WSG-EZhi2,
respectively. Under flooding stress, proline contents of
leaves increased significantly by 72.19, 80.96 and
22.37% for WTG-2541, WTG-2413 and WSG-EZhi2,
respectively (Fig. 1).
Effect of flooding stress on malondialdehyde
content: There were no significant differences among
MDA contents of the three tested materials before
flooding treatment with the values of 17.21, 18.06 and
16.06 µmol·g-1FW for WTG-2541, WTG-2413 and
WSG-EZhi2, respectively. Under flooding stress MDA
contents of leaves in three tested materials increased
(WTG-2541, WTG 2413 and WSG-EZhi2 increased by
7.74, 2.10 and 28.73%, respectively) (Fig. 2).
Effect of flooding stress on antioxidant enzyme
activity: SOD activities of WTG-2541 and WTG-2413
were slightly lower than that of WSG-EZhi2 before
Table 1: Effect of flooding stress on PN of three sesame seedlings’ leaves (μmol CO2/m2/s)
Cultivar (lines)
Treatment
48 h after flooding stress
3 days after restore growth
15 days after restore growth
WTG-2541
FS
6.330* (59.23%)
12.634* (39.70%)
21.733* (9.28%)
Control
15.528
20.953
23.794
WTG-2413
FS
7.260* (55.15%)
12.515* (35.87%)
24.620* (3.58%)
Control
16.186
19.515
25.535
WSG-EZhi2
FS
0.260* (98.32%)
10.405* (50.36%)
16.887* (28.29%)
Control
15.447
20.961
23.550
WTG: Water logging tolerant genotypes; WSG: Water logging sensitive genotype; FS: Flooding stress; *: Mean significance at 0.05 level
compared to control; Values in parentheses are relative percentage of flooding injury
353 Adv. J. Food Sci. Technol., 4(6): 352-356, 2012
Control
FS
35
70
Peroxidase activity
(U • g-1FW)
Proline content
(μg•g-1FW)
30
25
20
15
10
5
50
40
30
20
10
0
0
WTG-2541
WTG-2413
WTG-2541
WSG-EZhi2
Fig. 1: The effect of flooding stress on Proline (Pro) contents
in leaves of three sesame genotypes
The grey columns represent Pro contents of controls
and the white columns represent Pro contents of
sesames treated by flooding stress, respectively
7
6
Catalase activity
(U • g-1FW)
Malonialdehyde content
(μmol•g-1FW)
20
WSG-EZhi2
Fig. 4: The effect of flooding stress on Peroxidase (POD)
activities in leaves of three sesame genotypes
The grey columns represent POD activities of controls
and the white columns represent POD activities of
sesames treated by flooding stress, respectively
Control
FS
25
WTG-2413
Different genotype sesames
Different genotype sesames
15
10
5
0
5
Control
FS
4
3
2
1
0
WTG-2541
WTG-2413
WSG-EZhi2
WTG-2541
Different genotype sesames
Fig. 2: The effect of flooding stress on Malondialdehyde
(MDA) contents in leaves of three sesame genotypes
The grey columns represent MDA contents of controls
and the white columns represent MDA contents of
sesames treated by flooding stress, respectively
100
Superoxidase activity
(U • g-1FW)
Control
FS
60
80
Control
FS
60
40
20
0
WTG-2541
WTG-2413
WSG-EZhi2
Different genotype sesames
Fig. 3: The effect of flooding stress on Superoxide Dismutase
(SOD) activities in leaves of three sesame genotypes
The grey columns represent SOD activities of controls
and the white columns represent SOD activities of
sesames treated by flooding stress, respectively
flooding treatment. However, under flooding stress, the
SOD activities of WTG-2541 and WTG-2413 increased
by 17.04 and 19.99%, respectively. By contrast, the
WTG-2413
WSG-EZhi2
Different genotype sesames
Fig. 5: The effect of flooding stress on Catalase (CAT)
activities in leaves of three sesame genotypes
The grey columns represent CAT activities of controls
and the white columns represent CAT activities of
sesames treated by flooding stress, respectively
SOD activity of WSG-EZhi2 only increased by 6.30%,
which was smaller significantly than that of the two
WTGs (Fig. 3).
Effects of flooding stress on different antioxidant
enzyme activities were inconsistent. Peroxidase (POD)
activity of WTG-2541 was higher significantly (with
the value of 55.63 U·g-1FW) than WTG-2413 and
WSG-EZhi2 before flooding treatment. Under flooding
stress, the POD activities of WTG-2541 and WTG2413 increased respectively by 2.93 and 14.59%, while
it decreased by 24.90% for WSG-EZhi2 (Fig. 4).
CAT activities of WTG-2541 and WTG-2413 were
lower significantly than that of WSG-EZhi2 before
flooding treatment. However, under flooding stress, the
CAT activities of WTG-2541 and WTG-2413
decreased by 60.90 and 35.28%, respectively. By
contrast, the CAT activity of WSG-EZhi2 decreased by
78.78%, which was lower significantly than that of the
two WTGs (Fig. 5). This indicated the less effect of
flooding stress on WTG-2541 and WTG-2413 than on
WSG-EZhi2.
354 Adv. J. Food Sci. Technol., 4(6): 352-356, 2012
DISCUSSION
Hypoxia caused by flooding can induce a series of
responses in plants (Ou et al., 2011). One of the earliest
responses is stomata closure. Flooding can lead to
stomata closure in a short period and increase leaf
resistance. Stomata closure hinders CO2 absorption and
inhibits synthesis of 8-amino-propyl acetate (5-ALA).
Reduced CO2-fixation ability of chloroplast and
chemical changes of PSП system will lead to significant
decrease in leaf net photosynthetic rate (PN) (Beckman
et al., 1992). Our results showed that PN of the three
sesame cultivar (lines) dramatically decreased under
flooding stress. In addition, PN of WTG-2541 and
WTG-2413 declined at relatively lower degree
compared with that of WSG-EZhi2, indicating that the
former have relative stronger resistance to flooding
injury. Moreover, the less effect (flooding injury) on PN
in WTG-2541 and WTG-2413 than that in WSG-EZhi2
were also been observed when plants grew for 3 days
and/or 15 days at normal field conditions. Therefore,
the two newly cultivated sesame lines have the better
ability to cover from flooding injury than WSG-EZhi2.
The adaptation process of crops to adverse
environment is often accompanied by changes of some
osmolytes (Ou et al., 2011). Studies have shown that
under stress, plants are subjected to accumulation of
proline in cell (Xing and Cai, 1998). Proline
accumulation can enhance resistance of plant to
osmotic stress. Therefore, as an important cytoplasmic
penetrate and ant dehydrating agent, proline can reduce
cell osmotic potential, improve the water-holding
capacity of plant tissue and protect enzymes and
membrane in vivo (Ma, 1994). This study found that all
of the three tested sesames have increased proline
content under flooding stress, which proved the
improvement of proline under stress condition is one of
the self-defense reactions of plants (Wu et al., 1997).
Moreover, a greater increase of proline content in
WTG-2541 and WTG-2413 was observed than that in
WSG-EZhi2. The result showed that the two WTGs had
the higher reaction to flooding stress than WSG-EZhi2
cultivar.
As mentioned above, some authors thought
flooding stress can cause stomata closure, which will
reduce CO2 availability in the leaves and inhibit carbon
fixation (Crawford, 1978). Thus excessive excitation
energy in chloroplasts could increase the generation of
Reactive Oxygen Species (ROS) and induce oxidative
stress (Gossett et al., 1999). Hence the ROS production
in plants will increase under flooding stress (Ahmed
et al., 2002). In the current research, the injury of
biological lipid by ROS, as indicated by
Malondialdehyde (MDA) content was clearly detected
in the flooded plants, but with distinct difference
between the two genotypes, implying the possible
difference in their capacity of defense system against
ROS. The more increase of MDA in WSG-EZhi2 than
in WTG-2541 and WTG-2413 in our study indicated
that the latter lines own stronger resistant to oxidative
stress than WSG-EZhi2 cultivar.
Since Superoxide Dismutase (SOD) is present in
all aerobic organisms and sub cellular compartments
that generate activated oxygen, it has been assumed that
SOD has a central role in the defense against oxidative
stress (Scandalias, 1993; Zhang et al., 2007). It has
been generally showed that SOD activity is increased in
cells in response to diverse a biotic stresses including
salinity, drought, heavy metals and water logging.
Meloni et al. (2003) reported that salt-tolerant cotton
cultivar exhibited remarkable increase in SOD activity
under NaCl stress, whereas sail treatment had no
significant impact on SOD activity of salt-sensitive
cultivar. By contrast, Hwang et al. (1999) found that
water logging led to more increase in SOD activity for
water logging-sensitive cultivar of sweet potato than for
tolerant one. The results of the present study showed
that SOD activity of both the water logging tolerant
genotype (WTG-2541 and WTG-2413) and water
logging sensitive genotype (WSG-EZhi2) were
increased. Similarly, SOD activity of the two WTGs
had greatly increase compared with that of WSGEZhi2. Therefore, it may be assumed that an increase in
SOD activity under flooding stress could be indicative
of an increased production of ROS. However, a
dramatic decrease in SOD activity was also found in the
plants exposed to successively longer stresses (Ahmed
et al., 2002; Wu et al., 2003).
Simultaneous increase in activity of H2O2scanvenging enzyme, with accompanying increase in
SOD activity, is crucial for effective defense against
oxidative stress, or excessive accumulation of H2O2
caused by elevated SOD activity could result in
enhanced cyto-toxicity by the even more destructive
hydroxyl radical generated from H2O2 in a metalcatalyzed Haber-Weiss reaction (Gossett et al., 1999).
Peters et al. (1989) reported that POD activity was
higher in stress-tolerant bean than in sensitive one.
Meloni et al. (2003) found significant increase in POD
activity in salt-tolerant cotton cultivar when the plants
were exposed to salinity stress, whereas sensitive
cultivar remained unchanged. In the present study,
under flooding stress, POD activity increased in WTGs
while decreased in WSG. It can be concluded that rapid
development of higher POD activity under stress should
be a trail of tolerant plant species or genotypes,
enabling plants to protect themselves against the
oxidative stress (Zhang et al., 2007). However, in our
study, decrease dramatically of CAT activity was
observed in all of the three tested materials with
flooding treatment. The feasible interpretation had been
given by some authors (Mittler et al., 2004; Fu et al.,
2009): stress-induced decrease of photo-synthesis can
lead to reduced demand for NADPH in Calvin cycle
355 Adv. J. Food Sci. Technol., 4(6): 352-356, 2012
and consequently result in over-reduction of
photosynthetic electron transport, which eventually
leads to the formation of reactive oxygen. When plants
accumulate ROS, the contents of their endogenous
ROS-scavenging enzymes also decrease. Especially, a
more decrease of CAT activity in WSG-EZhi2 than in
WTG-2541 and WTG-2413 was observed. It also
means that more severe lipid per oxidation in WSGEZhi2, as indicated by higher MDA content may be
attributed to its inability in rapid development of higher
CAT activity when exposed to flooding stress.
CONCLUSION
Taking together, our study found that the two
WTGs had not only the better ability to recover from
flooding injury with the higher net photosynthetic rate
and proline contents, but also had the stronger activities
of active oxygen scavenger enzymes than WSG-EZhi2.
Therefore the new cultivated sesame lines (WTG-2541
and WTG-2413) had stronger resistant ability to
flooding stress than the WSG-EZhi2. Hence,
introducing and popularizing the two WTGs in the
Jianghan plains of Hubei province may improve
sesames’ resistant ability to adverse environments and
increase crop yields.
REFERENCES
Ahmed, S., E.
Nawata, M. Hosokawa and
T. Sakuratain, 2002. Alterations of photosynthesis
and some antioxidant enzymatic activities of
mungbean subjected to waterlogging. Plant
Sci., 163: 117-123.
Beckman, T.G., R.L Perry and J.A. Flore, 1992. Shortterm flooding affects gas exchange characteristics
of containerized sour cherry trees. Hort. Sci., 27:
1297-1301.
Boru, G., M.G. Van, W.E. Kronstad and L. Boersma,
2001. Expression and inheritance of tolerance to
water logging stress in wheat. Euphytica, 117:
91-98.
Crawford, R.M.M., 1978. Metabolic Adaptation to
Anoxia. In: Hook, D.D. and R.M.M. Crawford
(Eds.), Plant Life in Anaerobic Environment. Ann
Arbor Science Publishers Inc., Michigan, pp:
119-136.
Fu, Q.S., H.L. Li, J. Cui, B. Zhao and Y.D. Guo, 2009.
Effects of water stress on photosynthesis and
associated physiological characters of Capsicum
annuum L. Sci. Agric. Sin., 42: 1859-1866.
Gossett, D.R., E.P. Millhollon and M.C. Lucas, 1999.
Antioxidant response to NaCl stress in salt-tolerant
and salt-sensitive cultivars of cotton. Crop Sci., 34:
706-714.
Hohd, M.L., I. Shamsu, H. Qaiser, A. Shaheena and
A. Aqil, 2010. Physiological and biochemical
changes in plants under water logging.
Protoplasma, 241(1-4): 3-17.
Hwang, S.Y., H.W. Lin, R.H. Chen, H.F. Lo and F. Li,
1999. Reduction susceptibility to water logging
together with highlight stress is related to increases
in superoxide dismutase and catalase activities in
sweet potato. Plant Growth Regul., 27: 167-172.
Kozlowski, T.T., 1984. Extent, Causes and Impact of
Flooding. In: Kozlowski, T.T. (Ed.), Flooding and
Plant Growth. Academic Press, London, pp: 1-5.
Ma, Z.R., 1994. Study on free proline accumulation of
seedling in many species of plant under water
stress. Prat. Sci., 11: 15-18.
Meloni, D.A., M.O. Oliva, C.A. Martinez and
J. Cambraia, 2003. Photosynthesis and activity of
superoxide dismutase, peroxidase and glutathione
reductase in cotton under salt stress. Environ. Exp.
Bot., 49: 69-76.
Mittler, R., S. Vanderauwera, M. Gollery and F. VanBreusegem, 2004. Reactive oxygen gene network
of plants. Trends Plant Sci., 9: 490-498.
Ou, L.J., X.Z. Dai, Z.Q. Zhang and X.X. Zou, 2011.
Responses of pepper to waterlogging stress.
Photosynthetica, 49: 339-345.
Peters, J.L., F.J. Castillo and R.H. Heath, 1989.
Alteration of extracellular enzymes in pinto bean
leaves upon exposure to air pollution, ozone and
sulfur dioxide. Plant Physiol., 89: 159-164.
Scandalias, J.G., 1993. Oxygen stress and superoxide
dismutase. Plant Physiol., 101(1): 7-12.
Wu, L., Y.D. Li, Z.D. Zhang and R. Hao, 1997. A
comparison of physiological and morphological
reactions of three types of blueberries to flooding
stresses. Acta Hort. Sin., 24: 287-288.
Wu, F.B., G.P. Zhang and P. Dominy, 2003. Four
barley genotypes respond differently to cadmium:
Lipid peroxidation scavenging system. J. Exp. Bot.,
9: 1097-1109.
Xing, S.C. and Y.H. Cai, 1998. The relationship
between stresses and proline. J. Ecol. Agric., 2:
30-33.
Zhang, G.P., K. Tanakamaru, J. Abe and S. Morita,
2007. Influence of water logging on some antioxidative enzymatic activities of two barley
genotypes differing in anoxia tolerance. Acta
Physiol. Plant, 29: 171-176.
356