Assiut Univ. J. of Botany
43(1), P-P 29-55 (2014)
PHYSIOLOGICAL AND METABOLIC RESPONSES OF TWO
OIL- PRODUCING PLANTS TO SALT AND ALKALI STRESSES
Radi A. A.*, Farghaly F. A.*, Abdel-Wahab D. A.**, and Hamada A. M.*
* Botany and Microbiology Department, Faculty of Science, AssiutUniversity,
Assiut, 71516 Egypt
**
Botany Department, Faculty of Science, AssiutUniversity, New Valley, Egypt
A
Corresponding author e-mail: [email protected]
[email protected]; [email protected]; [email protected]
Received:22/4/2014
Accepted:19/6/2014
In arid and semiarid regions, salinity is among the most important abiotic factors
limiting growth of crop plants and yield. The current study was carried out to
evaluate some metabolic and physiological responses of two oil – producing plants
(sunflower and jojoba) grown under osmotic and toxic phases of NaCl and Na2CO3
salts. The two applied salts at the two selected phases markedly decreased salt
tolerance index, photosynthetic pigments, anthocyanin pigment, soluble proteins
and sodium accumulation factor of shoots and roots of jojoba and sunflower plants.
This reduction was significant at the second phase of the applied salts. On the other
hand, Na+ concentration and Na+/K+ ratio in shoots and roots of the test plants was
increased by increasing NaCl or Na2CO3 level. Moreover, the leakage of K+ and Na+
from leaves of the stressed plants was also increased. Furthermore, NaCl and
Na2CO3 supply stimulated glucose, fructose, proline and other free amino acids
accumulation in shoots of jojoba and sunflower plants. Sunflower exhibited higher
sensitivity to the applied salts compared with jojoba plant.
Key words: alkalinity, jojoba, salinity, sunflower.
INTRODUCTION
As an extreme reflection of land desertification, excess of salt and
alkali in soils is a widespread and increasing environmental problem that
affects plant growth and crop productivity worldwide.
At present, only 5.4 percent of the land resources in Egypt
represent intensive cultivated land, and about 40 percent of it is subject to
salinity, sodicity and waterlogging problems (MALR, 2009). Saline and
sodic (alkali) soils significantly reduce the value and productivity of
irrigated land. Soil salinity and all the relevant problems generally occur
in Egypt, where arid or semi-arid climate prevails and consequently
rainfall is insufficient to leach soluble salts from the soil or where surface
or internal soil drainage is restricted (Mohamedin et al., 2010). The total
30
Radi A. A., Farghaly F. A., Abdel-Wahab D. A., and Hamada A. M.
salt concentration, composition of salts and the ratio of neutral salts to
alkaline ones vary with different soils.
Soil salinity is a considerable problem adversely affecting
physiological and metabolic processes, significantly reducing plant
growth and yield (Cuartero et al., 2006). In this context, plants response
in two separate phases towards salinity stress: The first, osmotic phase
mainly reduces plant root ability to water uptake and curtails shoot
growth. Furthermore, in this osmotic phase leaves expansion ratio, new
leaves emergence and lateral buds development are negatively affected.
The second, ion toxicity phase, take place when concentration of ions
(mostly Na+ and Cl-) increases to a certain level, plant cell cannot storage
the accumulated ions consequently cells begin to die due to ionic
imbalance which interrupts the uptake of essential mineral nutrients,
phytohormone levels, transpiration, photosynthesis, and biomass
production (Hagemeyer, 1997). Moreover, Na+-induced oxidative stress
may result in, lipid peroxidation, protein oxidation and membrane injuries
(Hagemeyer, 1997; Daneshmand et al., 2010). The detrimental Na+
concentrations depend on plant species, plant organ and developmental
stage (Munns, 2002).
The problems of soil alkalization due to NaHCO3 and Na2CO3
may be more severe on plant growth and metabolism than those achieved
by neutral salts, such as NaCl and Na2SO4, as the alkaline salts are more
destructive to plants than neutral ones (Yang et al., 2007). High
exogenous neutral salt concentrations cause an imbalance of cellular ions
resulting in osmotic stress, ion toxicity, and the production of ROS
(Cramer et al., 1994). Alkalinity exerts similar responses but with the
added influence of stress due to high pH. The high pH environment
surrounding the roots may directly inhibit ion uptake by causing Ca2+,
Mg2+ and H2PO4- to precipitate (Yang et al., 2007) and consequently
disrupt the ion uptake. Thus, in the light of the precedent gross
disturbances induced by salt stress, it could be conceded that selection of
relatively resistant horticultural crops will be a necessity for the
utilization of lands prone to salinization (Wahome, 2003).
In this context, this work may secure additional data on some
metabolic and physiological responses to salinity and sodicity in two oilproducing plants (jojoba and sunflower) as an attempt to evaluate
differences between them, which might be of importance in controlling
salt resistance.
Physiological and Metabolic Responses of Two Oil- Producing Plants to Salt…. 31
Jojoba as an important oil- producing plant can grow successfully
in semi-arid regions covering a surface of about 8500 ha (Canoira et al.,
2006; IJEC, 2008). The world production of jojoba is expected to grow
markedly over the next decade. This plant has been first introduced into
the Egyptian agricultural map in 1990’s around Assiut city (375 Km south
of Cairo). Since a considerable area of the Egyptian soil (more than 90%)
is desert, inhabiting jojoba for oil production in the Egyptian desert is
extremely preferable, not only for oil production but may also be
protective against desertification.
Renewed interest in commercial cultivation of jojoba has begun
due to the useful properties of its liquid wax in the pharmaceutical,
cosmetic and lubricant industry (Mills et al., 2001). Jojoba is unique
among plants in the fact that its seeds contain about 40–50% , oil (Rana et
al., 2003), which is more than twice the amount of oil in soybeans and
somewhat more than that in most oilseed crops.
Among the various characteristics of this species is its drought and
salt tolerance, which make this crop a profitable alternative for arid and
semiarid zones around the globe (Mills et al., 1997). These droughtresistant trees, which are known to produce double their yield with
supplementary irrigation, can produce nine times and even much higher if
fertilization is provided. Even if the fertility of the soil is marginal, jojoba
is still able to produce well without the use of fertilizers (Tremper, 1996).
In addition, the pressing of jojoba seeds is easily achieved using a screw
press and dry cake is used as fertilizer after the oil is extracted by solvents
whenever that is desired. Therefore, it can be said that jojoba is an
environment-friendly tree because it is evergreen, produces oil rich seeds
and it grows with a minimum water requirement (less than 100 mm of
rain or its equivalent by drip irrigation). The tree also can be grown safely
using treated wastewater and brackish water (Tremper, 1996). A large
surface of saline desert, which is of very limited use, could be exploited
by the introduction of jojoba.
Sunflower is also an important oilseed crop supplying more than
13% of the total edible oil produced globally (Rauf et al., 2008 ).
Sunflower requires shorter period to complete its life cycle than other
field crops. The high quantities per unit area and the quality of edible oil
(rich in linoleic and oleic acids) are the prime factors proving its
versatility which allow this crop to be grown in 68 countries (FAO,
2010). Certain other characteristics such as its robustness and extensive
tap root system or osmo-regulatory mechanisms have induced tolerance in
32
Radi A. A., Farghaly F. A., Abdel-Wahab D. A., and Hamada A. M.
the crop to perform better under water-limited conditions (Rauf and
Sadaqat, 2008; Rauf et al., 2009) .
Sunflower is also an important crop in Mediterranean areas where
salinity is an increasing problem (Di Caterina et al., 2007). This oilproducing crop is moderately sensitive to soil salinity. The promotion of
sunflower could be successful to increase the domestic production
provided proper cultivars are available (Khatoon et al., 2006). Sunflower
seeds contain 25-48 % oil and 20-27 % protein. Sunflower oil is quite
palatable, contains soluble vitamins A, D, E and K. Moreover, it used in
manufacturing of margarine. Sunflower cake is used as cattle feed
(Hussain et al., 2006). On the basis of crop water stress index (Katerji et
al., 2000) categorized sunflower as salt tolerant crop. Furthermore, as it
requires less number of irrigations, it may be successfully cultivated by
applying saline sodic water with little harmful effects on physicochemical
properties of the soil.
The present situation of oilseed production in Egypt revealed that
only 10% of edible requirement offered through the local production and
about 90% is supplied through importation. To solve this problem, the
crop growers must cultivate non-conventional oilseed crops along with
the conventional ones.
This study carried out to evaluate physiological and metabolic
responses of the two oil- producing plants to salt and alkali stresses which
might be of important role in achieving and controlling the salt tolerance
of the test plants.
MATERIALS AND METHODS
Plant growth and harvest
Jojoba (Simmondsiachinensis, (Link) Schneider) and sunflower
(Helianthus annuus) cultivar Sakha 53 well-selected seeds were surfacesterilized in 95% ethyl alcohol for 2 min. and then transferred to sodium
hypochloride activated with 1% Cl for 10 min., rinsed with distilled water
then soaked for 24 h in distilled water. Finally planted in plastic pots lined
with polyethylene bags filled with air-dried and cleaned quartz sand,
watered with a nutrient solution (Hoagland and Arnon, 1950) and kept
approximately at 100% field capacity. Plants were grown (2011-2012) in
an outdoor green house at Faculty of Science, Assiut University under
natural conditions of temperature, humidity and light. After developing
true leaves, 10 day- old for sunflower and 30 day- old for jojoba, plants
Physiological and Metabolic Responses of Two Oil- Producing Plants to Salt…. 33
were subdivided into three subsets: The first subset without salts
(control), the second treated with different concentrations of NaCl and the
third treated with different concentration of Na2CO3. Sunflower plants
were grown under different concentrations of NaCl (80 and 160 mM) and
Na2CO3 (10 and 40 mM), while jojoba plants were treated with different
concentrations of NaCl (160 and 400 mM) and Na2CO3 (20 and 100 mM)
and adopted with six replicates.
At the end of the experimental salinization period (15 days), the
test plants were fractionated into roots and shoots. The roots were rinsed
with distilled water and blotted gently with filter paper. The shoots and
roots were quickly weighed separately for fresh weight (FW)
determination. The dry weight (DW) was obtained after drying the plant
tissues for 48 h at 72ºC. On other hands, fresh samples of plants were
harvested; roots and leaves were immediately frozen in liquid nitrogen
and stored at -80 ºC for biochemical analysis.
Salt tolerance index
This value was calculated as given by Seydi et. al.,(2003) as the ratio of
the total dry weight of plants subjected to different salt concentrations to
the total dry weight of control ones.
Salt tolerance index (%) = (TDW at Sx / TDW at S0) × 100.
TDW at S0= Total dry weight at control, control,
TDW at Sx = Total dry weight at given concentrations.
Determination of photosynthetic pigments
The photosynthetic pigments (mg/g FW) were estimated using the
spectrophotometric method recommended by Lichtenthaler (1987).
Determination of anthocyanin
Anthocyanin pigments were measured
described
by Mancinelli
(1990).
Using
spectrophotometer and calculated as mg/g FW.
calorimetrically as
Unico
UV-2100
Determination of sodium and potassium ions
Sodium (Na+) and K+ in the dried ground shoot and root material
were determined following the method of Allen (1989). The samples so
digested were diluted up to 50 ml in a volumetric flask and filtered. The
filtrate was used for the determination of Na+ and K+ using Jenway
PFP7/C flame photometer (Williams and Twine, 1960). The accumulation
34
Radi A. A., Farghaly F. A., Abdel-Wahab D. A., and Hamada A. M.
factor of Na+ was mainly determined as the correlation between [Na+]
plant and the [Na+] medium (Bergqvist and Greger, 2012).
Determination of ion leakage
Cell membrane stability was carried out as given by Premachandra
et al. (1992) with minor modifications. Fresh leaf discs of the test plants
(three cm in diameter, and 4 in numbers) were washed with de-ionized
water, then submerged in 30 ml distilled water for 24 hours at 10 oC,
autoclaved for 15 min., cooled at 25 oC. Potassium and sodium ion
leakage was determined before and after autoclaving by flame photometer
according to the method described by Williams and Twine (1960). Each
assay achieved using three replicates for each treatment.
Determination of glucose and fructose
Glucose and fructose were quantified in 80% (v/v) ethanol
extracts of dry leaf tissues. The dry tissue samples were shaken in 10 ml
80% ethanol. The insoluble fractions were washed with 5 ml 80%
ethanol. The soluble fractions were centrifuged at 5000 g for 10 min. the
supernatants were collected and stored at 4 ºC. Glucose and fructose were
analyzed by reacting 0.5 ml extract with 2.5 ml freshly prepared anthrone
(150 mg anthrone + 100 ml H2SO4) and placed for glucose in a boiling
water bath for 5 min and for fructose in water bath at 40 ºC half hour
(Halhoul and Kleinberg, 1972). After cooling the absorbance at 625 nm
was determined by a Unico UV-2100 spectrophotometer.
Determination of free amino acids
Dry tissue samples were boiled in 5 ml distilled water for two
hours. After cooling, the water extract was centrifuged and the
supernatant was completed to a definite volume by distilled water, then
free amino acids were determined according to the adopted by Moore and
Stein (1948). A calibration curve was constructed using glycine. The free
amino acids concentration calculated as mg/g DW.
Determination of soluble proteins
Soluble proteins content was determined by folin phenol reagent
according to Lowery et. al.,(1951)
Determination of proline
Free proline content was determined according to Bates et al.
(1973). Shoot samples were homogenized in 3% sulfosalicylic acid, then
filtered. After addition of acid ninhydrin and glacial acetic acid, the
Physiological and Metabolic Responses of Two Oil- Producing Plants to Salt…. 35
resulting mixture was heated at 100 ºC for 1 h in water bath. Reaction was
stopped by using ice bath. The mixture was extracted with toluene and
mixed vigorously. The chromophore containing toluene was aspired from
the aqueous phase and the absorbance was measured at 520 nm. Proline
concentration was determined using calibration curve and expressed as
mg/g DW.
RESULTS
Salt tolerance index
Salt tolerance index is considered as marker for the response of
different plants to salt stress. The salt tolerance index of jojoba and
sunflower plants decreased with increasing of NaCl or Na2CO3 in the
culture media (Fig. 1A, B). The reached decrease was significant at the
second phase of salinity or alkalinity. Although, the applied levels of
NaCl or Na2CO3 were less in case of sunflower than in jojoba, sunflower
plants were more sensitive to salt stress compared to jojoba plants.
Figure 1. Salt tolerance index of jojoba (A) and sunflower (B) plants as affected by
different concentrations of NaCl and Na2CO3. The mean value of four
replicates was adopted, and the vertical bars indicate + SE. Different letters
indicate significant variations at P< 0.05.
Photosynthetic and non-photosynthetic pigments
The pigment concentrations (total photosynthetic pigments and
anthocyanin) in leaves of salt stressed jojoba or sunflower plants are
presented in Fig. 2A-D. The data herein obtained clearly demonstrate that
NaCl or Na2CO3 stress affected the biosynthesis of photosynthetic (Ps.)
and anthocyanin (Anth.) pigments. The biosynthesis of all pigments
decreased with the rise of salt level from first to second phase in the
culture media of jojoba or sunflower plants. In addition, the data reveal
36
Radi A. A., Farghaly F. A., Abdel-Wahab D. A., and Hamada A. M.
that the constitutive content Ps. and Anth. pigments in sunflower and
jojoba plants were nearly at the same level.
Jojoba
Sunflower
Figure 2. Photosynthetic and anthocyanin pigments of jojoba (A, B) and sunflower (C,
D) plants as affected by different concentrations of NaCl and Na 2CO3. The
mean value of four replicates was adopted, and the vertical bars indicate + SE.
Different letters indicate significant variations at P< 0.05.
Sodium ion concentration
The data in Tables 1 and 2 clearly demonstrate that increasing the
level of NaCl or Na2CO3 increased Na+ concentration in roots and shoots
of jojoba and sunflower plants. The highest Na+ concentration in roots
and shoots consistently achieved in plants grown at the second phase of
both applied salts. It is worth to mention that Na+ was much higher in
sunflower organs compared with the jojoba ones under NaCl or Na2CO3
stress. The concentration of Na+ in shoot and root negatively correlated
with the salt tolerance index, total photosynthetic, and anthocyanin
pigments of both test plants. This correlation was mostly higher in jojoba
compared to sunflower plants.
Physiological and Metabolic Responses of Two Oil- Producing Plants to Salt…. 37
Accumulation factor of sodium
The accumulation factor is the correlation between the Na+
concentration in the medium and its Na+ concentration in the test plant.
The accumulation factor of roots and shoots of jojoba and sunflower
plants decreased with the rise of Na+ level in the culture media (Tables 1
and 2). There was a strong positive correlation between Na+ accumulation
factor and dry weight of roots and shoots, while there was a strong
negative correlation between Na+ concentration and its accumulation
factor in roots and shoots of the test plants. It is interesting to note that the
positive coloration was generally higher in jojoba compared to sunflower
plant, while opposite trend was exhibited in case of negative correlation.
These results confirmed the lower accumulation factor and Na+
concentration in shoots and roots of jojoba than sunflower plants.
[Na+] shoot and [Na+] root ratio
Ion exclusion at the level of xylem is considered as marker for the
transport-activity and accumulation of ions into the shoot. In jojoba and
sunflower plants, [Na]shoot:[Na]root showed a slight increase or decrease
than control at two the levels of NaCl or Na2CO3 (Tables 1 and 2). The
data herein obtained indicate that the higher levels of NaCl or Na2CO3
concentration in culture media did not affect the translocation of Na+ from
root to shoot in both test plants. This result is confirmed by the week
correlation between [Na]shoot:[Na]root and Na+ concentration in roots and
shoots.
Sodium potassium ratio
The Na+/K+ ratio often used as a criterion for the selection of
sensitivity and/or resistance to abiotic stresses (Flowers, 2004). The
results in Tables 1 and 2 indicate that in jojoba and sunflower plants
Na+/K+ ratio of shoots and roots was markedly increased by increasing
NaCl or Na2CO3 level in the culture media. The data reveal also that
Na+/K+ ratio was higher in sunflower shoots compared with the jojoba
ones. The stimulatory effect in both test plants correlated by negative
correlation between Na+/K+ ratio and K+ concentration in both test plants
was significant under the studied salinization levels in relation to control.
However, the correlation between Na+/K+ ratio and Na+ concentration
was positive.
38
Radi A. A., Farghaly F. A., Abdel-Wahab D. A., and Hamada A. M.
Table 1.Sodium concentration, accumulation factor, [Na] shoot to [Na]
root ratio and sodium to potassium ratio in shoots and roots of
jojoba plants as affected by different concentrations of NaCl and
Na2CO3. The results are means of four replicates (+ SE).
Different letters are capital for Na2CO3 and small for NaCl
treatments, significantly different at P< 0.05.
Treatment
(mM)
0
NaCl
160
400
Na2CO3
20
100
Na concentration
(mg/g DW)
Accumulation factor
Na+/K+
[Na]shoot:[Na]root
Shoot
14.61+
0.880aA
28.95+
1.876b
Root
11.58+
0.644aA
17.06+
0.366b
Shoot
644.42+
31.814aB
7.87+
0.509a
Root
524.29+
20.620bB
4.63+
0.099a
1.31+
0.085aB
1.696+
0.094b
Shoot
0.849+
0.008aA
1.694+
0.188b
46.37+
0.826c
20.18+
0.812B
33.01+
0.800c
18.86+
1.055B
5.04
+0.089b
21.95+
0.883A
3.59+
0.086a
20.38+
0.303A
1.407+
0.055a
1.078+
0.053A
2.740+
0.063c
1.327+
0.081B
48.98+
0.561C
31.86
+1.055C
10.65+
0.121A
6.93+
0.229A
1.540+
0.039C
3.616+
0.048C
Root
1.66+
0.041aA
2.088+
0.015b
6.471+
0.111c
2.486+
0.041B
5.708+
0.640C
Table 2. Sodium concentration, accumulation factor, [Na] shoot to [Na]
root ratio and sodium to potassium ratio in shoots and roots of
sunflower plants as affected by different concentrations of NaCl
and Na2CO3. The results are means of four replicates (+ SE).
Different letters are capital for Na2CO3 and small for NaCl
treatments, significantly different at P< 0.05.
Treatment
(mM)
NaCl
0
80
Na2CO3
160
10
40
Na concentration
(mg/g DW)
Shoot
31.1+
1.90aA
54.07+
2.11b
71.15+
4.48c
36.99+
4.43A
55.35+
2.66B
Root
29.27+
0.630aA
50.5+
3.355b
64.92+
2.168c
50.5+
1.250B
58.59+
0.653C
Accumulation factor [Na]shoot:[Na]root
Shoot
1315.30+
82.88bB
29.39+
1.149a
19.33+
1.22a
40.23+
4.816B
12.04+
0.578A
Root
1272.7+
27.67bB
27.45+
1.82b
17.64+
0.59a
54.44+
1.36B
12.74+
0.142A
1.114+
0.092aB
1.08+
0.098a
1.097+
0.074a
0.743+
0.105A
0.944+
0.035AB
Na+/K+
Shoot Root
1.52+ 2.65+
0.059aA 0.129aB
2.59+ 3.091+
0.03b 0.149a
4.357+ 5.423+
0.219c 0.227b
1.489+
1.530+
0.156A 0.049A
4.051+ 3.730+
0.121B 0.005C
Sodium and potassium leakage
The cellular membrane dysfunction due to stress is well expressed
by increased permeability and leakage of ions, which can be readily
measured by the efflux of electrolytes. The efflux of K+ and Na+ from
Physiological and Metabolic Responses of Two Oil- Producing Plants to Salt…. 39
leaves of jojoba and sunflower plants as affected by NaCl and Na2CO3
supply is presented in Fig. 3A, B. Potassium leakage from jojoba and
sunflower leaves significantly increased with the increase of NaCl supply,
while Na2CO3 application had no significant effect. The leakage was
more pronounced in sunflower than in jojoba plants. Furthermore, Na+
leakage from leaves of the test plant was significantly enhanced by the
applied levels of NaCl and Na2CO3.
Figure 3. Potassium and sodium leakage from leaves of jojoba, 30-d-old (A) and sunflower,
10-d-old (B) plants as affected by different concentrations of NaCl and Na2CO3.
Each result is a mean of four replicates, and the vertical bars indicate + SE. Different
letters indicate significant variations at P< 0.05.
Glucose and fructose
The results presented in Fig. 4A, B demonstrate that, NaCl or
Na2CO3 at the two applied phases generally had a significant stimulatory
effect on the accumulation of glucose and fructose in leaves of the test
plants. It is worth to mention that, in case of jojoba plant, the biosynthesis
of glucose was consistently higher than fructose, while in sunflower, this
trend not achieved specially under the applied NaCl levels.
Figure 4. Glucose and fructose content of jojoba, 30-d-old (A) and sunflower, 10-d-old (B)
plants as affected by different concentrations of NaCl and Na 2CO3. Each result is a mean of
four replicates, and the vertical bars indicate + SE. Different letters indicate significant
variations at P< 0.05.
40
Radi A. A., Farghaly F. A., Abdel-Wahab D. A., and Hamada A. M.
Soluble proteins
The data presented in Fig. 5A,B show that NaCl and Na2CO3, at the
applied levels, had an inhibitory effect on the accumulation of soluble
proteins in leaves of jojoba and sunflower plants. It is interesting to note
that soluble proteins were much higher in jojoba shoots compared with
sunflower ones.
Figure 5. Soluble proteins in leaves of jojoba, 30-d-old (A) and sunflower, 10-d-old (B)
plants as affected by different concentrations of NaCl and Na 2CO3. Each result is a mean of
four replicates, and the vertical bars indicate + SE. Different letters indicate significant
variations at P< 0.05.
Proline and other free amino acids
The two applied salts affected on proline and other amino acids
biosynthesis in shoots of jojoba and sunflower plants. The results are
presented in Fig. 6A, B clearly demonstrate that, in most cases, the increase
in NaCl or Na2CO3 supply generally had a stimulatory effect on the
accumulation of proline and other free amino acids in the shoots of the
two test plants. In addition, the results herein obtained reveal that proline
biosynthesis was much lower in jojoba compared with sunflower.
Physiological and Metabolic Responses of Two Oil- Producing Plants to Salt…. 41
Figure 6. Proline and other amino acids of jojoba, 30-d-old (A) and sunflower, 10-d-old (B)
plants as affected by different concentrations of NaCl and Na 2CO3. Each result is a mean of
four replicates, and the vertical bars indicate + SE. Different letters indicate significant
variations at P< 0.05.
DISCUSSION
The conditions prevailing in saline habitats were known to have
deleterious effects on plant growth and the relevant metabolic activities.
These effects intensively investigated at present to recognize and
understand the different mechanisms underlying and controlling salt
tolerance in plants.
As salt stress decreases the osmotic potential of a growing
medium, discriminatory uptake of ions can lead to an imbalanced
accumulation of ions in plant tissues that compel the plant to restrict
growth, a response that could ascribed particularly to intensity of the
stress imposed. In the present study, salt and alkali stresses markedly
inhibited jojoba and sunflower growth. However, deleterious effects of
salt or alkali stress on salt tolerance index were more pronounced in
sunflower than jojoba plants. In addition, the concentration of Na+ in
shoot and root negatively correlated with the salt tolerance index. In this
context, the reached correlation was mostly higher in jojoba compared to
sunflower plants.
Although growth reduction in most plants is a common response
effect of salinity stress (Abbas et al., 2010; Akram et al., 2012), however,
the actual physiological and biochemical mechanisms involved in growth
reduction are still not well determined (Munns and Tester, 2008; Ashraf
et al., 2011; Shaheen et al., 2013). A number of plausible explanations for
the reduction in growth and productivity of salt stressed plants involve
disturbed osmotic relations, nutritional and hormonal imbalance in
42
Radi A. A., Farghaly F. A., Abdel-Wahab D. A., and Hamada A. M.
addition to salt– induced oxidative stress (Hu et al., 2012). The alkaline
salts could cause damages to plants through both salt stress and pH stress
(Shi and Sheng, 2005). In addition, the retarded growth in response to
alkaline salts may be a consequence of the retarded availability of
micronutrients which are essential to plant growth (Cardarelli et al., 2010).
Photosynthetic pigments are the key components involved in the
light phase of photosynthesis. It is widely reported that almost all
different types of stresses including salinity cause damage to thylakoid
membranes, the site wherein all different types of photosynthetic
pigments accumulated. In the current study, the biosynthesis of
photosynthetic pigments decreased with the rise of salt level in the culture
media of jojoba or sunflower plants. The degradation of chlorophyll
pigments under salt-stress could be attributed to increased activity of
chlorophyllase or reduced de novo synthesis of chlorophyll (Ashraf and
Harris, 2013). Furthermore, salt stress can break down chlorophyll, the
effect ascribed to increased level of the toxic cation, Na+(Li et al., 2010).
A series of experiments with sunflower callus and plants (Santos and
Caldeira, 1999; Akram and Ashraf, 2011) have shown that the important
precursors of chlorophyll, i.e., glutamate and 5-aminolaevulinic acid,
decreased in salt-stressed calli and leaves, a response which indicates that
salt stress affects more markedly chlorophyll biosynthesis than
chlorophyll breakdown.
Apart from the photoprotective function of anthocyanin,
shielding the chloroplast from excess light by absorbing blue-green light
(Merzlyak et al., 2008), and scavenging active oxygen species (AOS)
(Gould et al., 2002; Kytridis and Manetas, 2006). These plant pigment
can bind toxic ions, and thus protect chloroplasts and cytoplasmic
structures from the adverse effects of salinity, and allow sufficient plant
photosynthetic assimilation (Gould et al., 2002). In the present study, salt
and alkali stresses decreased progressively the leaf anthocyanin content in
jojoba and sunflower plants. These results in accordance with other
studies indicate specific degradation of anthocyanins due to either
developmental or environmental changes (Oren-Shamir, 2009). The low
levels of anthocyanin observed in many plants when grown at elevated
temperatures may be a combination of a slower rate of biosynthesis
(Shvarts et al., 1997) and increased catabolism. The catabolic process
may be due either to chemical instability of the pigments or to specific
enzymatic activity (e.g. β-glucosidases, peroxidases) present in the
vacuoles decreasing the pigment concentration in plant tissues (OrenShamir, 2009).
Physiological and Metabolic Responses of Two Oil- Producing Plants to Salt…. 43
Further evidence of the role played by two salinizing agents (NaCl
and Na2CO3) in modifying ion uptake and accumulation obtained from
the data presented in this investigation where the accumulation factor of
Na+ decreased with increasing its concentration in medium. Accumulation
of Na+ also depends on the plant species; this clearly displayed by the
higher Na+ accumulation in sunflower compared to jojoba although
sunflower was grown at lower levels of the salinizing agents. The
differential Na+ accumulation could depend on the plant capacity to limit
Na+ uptake by the roots. This may explain the low Na+ concentration in
the roots of the test plants under salt stress conditions. Moreover, ion
accumulation ability of plants contributes towards their salinity tolerance.
This confirmed by our results where the constitutive Na+ accumulation
factor of shoots and roots was lower in jojoba than sunflower plant. In
addition, the accumulation factor of roots and shoots of jojoba and
sunflower plants decreased with the rise of Na+ level in the culture media.
However, there was a strong positive correlation between Na+
accumulation factor and dry weight of roots and shoots, while there was a
strong negative correlation between Na+ concentration and its
accumulation factor in roots and shoots of test plants. Salt-tolerant plants
accumulate lower levels of toxic Na+ as compared to that in salt-sensitive
plants (Horie et al., 2012). On the other hand, the plant may decrease the
permeability of the plasma membrane to Na+ to minimize Na+ influx into
the cytosol (Anil et al., 2007; Senadheera et al., 2009). The negative
association between Na+ content and fresh weight of plant has been
reported in wheat (Saqib et al., 2006), rice (Haq et al., 2009) and maize
(Akram et al., 2010).
On the other hand, jojoba exhibited comparatively lower
endogenous levels of Na+ than sunflower. The concentration of Na+ in
shoot and root negatively correlated with the salt tolerance index, total
photosynthetic, and anthocyanin pigments of both test plants, and this
correlation was mostly higher in jojoba compared to sunflower plants.
Negative correlation between Na+ and dry weight suggests that plant
growth was inhibited by accumulation of Na+ under salinity stress. Thus,
avoiding Na+ accumulation in saline environments could be an important
mechanism contributing to ionic tolerance (Tang et al., 2013). The Na+
extrusion from the cytosol in some way, is associated with H+ influx into
the cytosol, which in turn activates the H+-ATPases (Kader et al., 2007)
leading to a pHcyt increase with time, as reported for Triticum aestivum
cultivar Seds1 (Morgan et al., 2013). In the more sensitive cultivar
Vinjett, [Na+]cyt significantly accumulated with no significant pHcyt
44
Radi A. A., Farghaly F. A., Abdel-Wahab D. A., and Hamada A. M.
changes in contrast to the more resistant cultivar cultivar Seds1 (Morgan
et al., 2013).
One key mechanism of salinity tolerance is the ability of a plant to
control Na+ transport at both the tissue and cellular level, either by
secreting Na+ into tissues, cells and organelles where it can do little
damage, or by minimizing the amount of Na+ entering the plant through
its roots (Munns and Tester, 2008). Ion exclusion at the level of xylem is
considered as marker for the transport-activity and accumulation of ions
into the shoot. In this investigation, [Na]shoot:[Na]root in jojoba and
sunflower plants, showed a slight increase or decrease than control at the
two levels of NaCl or Na2CO3. These data indicate that increasing NaCl
or Na2CO3 concentration in culture media did not affect the translocation
of Na+ from root to shoot in both test plants. This results confirmed by the
week correlation between [Na]shoot:[Na]root and Na+ concentration in roots
and shoots. Our results agree with those reached by Jha et al. (2010) who
suggested that Na+ exclusion in Arabidopsis is not linked to salinity
tolerance as strongly as in case of cereals. However, there is increasing
evidence that shoot Na+ exclusion is not the only mechanism of salinity
tolerance in cereals; some studies on Australian bread wheat varieties
(Genc et al., 2007) and of near-wild relatives of wheat, such as Triticum
monococcum (Rajendran et al., 2009), reveal a lack of correlation
between shoot Na+ and tolerance.
Salt stress is known to decrease the endogenous levels of K+ in
plants as Na+ competes with the uptake of K+(Tunuturk et al., 2011). In
this study, it observed that Na+/K+ ratio of shoots and roots of jojoba and
sunflower plants markedly increased by increasing NaCl or Na2CO3
concentration in the culture media. Furthermore, Na+/K+ ratios were
higher in sunflower shoots than in jojoba ones. The stimulatory effect in
both test plants correlated by negative correlation between Na+/K+ ratio
and K+ concentration in both test plants under the applied salinization
levels. However, the correlation between Na+/K+ ratio and Na+
concentration was positive. Similarly, Mills and Benzioni (1992) working
with nodal segments of jojoba in vitro has also found a drastic decline of
K+ concentration under salinity stress. Leaf relative Na+ exclusion usually
results in high leaf K+: Na+ ratios, which have also been suggested to be
associated with salt tolerance in sunflower (Ashraf and Tufail, 1995).
This ratio obviously tended to decrease under saline conditions
(Di Caterina et al., 2007), but its values cannot be unequivocally
associated with salt resistance (Shahbaz et al., 2010).
Physiological and Metabolic Responses of Two Oil- Producing Plants to Salt…. 45
Plants under different environmental stresses exhibit changes in
membrane permeability that ultimately leads to loss of integrity
(Farkhondeh et al., 2012). Stability of biological membranes has been
taken as an effective screening tool to assess the salinity stress effects
(Kukreja et al., 2005). In the present investigation, Na+ leakage from
jojoba and sunflower leaves was stimulated by the applied levels of NaCl
and Na2CO3. While, K+ leakage from leaves of the test plant significantly
increased under NaCl supply, there was no significant effect on its
leakage under Na2CO3 supply. The K+ leakage was more pronounced in
sunflower than in jojoba plants. However, salt-induced increase in Na+
leakage was greater in jojoba than that in sunflower. Our findings
corroborate well with the results reported for other crop plants, such as
rice (Siringam et al., 2011), sugar beet (Farkhondeh et al., 2012) and
maize (Hussain et al., 2013). Salt-induced increase in relative membrane
permeability is generally lower in salt-tolerant cultivars as compared to
that in salt-sensitive ones (Heidari et al., 2011; Hussain et al., 2013).
Plant growth and development depends substantially on
carbohydrate metabolism, particularly glucose and fructose (Foyer and
Shigeoka, 2011). Soluble sugars including glucose, fructose and sucrose
are evidently enriched when plants are subject to salt stress, especially in
salt-tolerant genotypes (Chen et al., 2008; Cha-um et al., 2009). They are
not only involved in osmoregulation mechanisms within the cell,
controlling water potential and osmotic potential, but also help in
detoxification by acting as chelating agents to trap Na+ within starch
granules. Interestingly, soluble sugars act as signal molecules and are also
involved in regulating genes related to salt-tolerance defense mechanisms
(Gupta and Kaur, 2005). It has been reported that alkali stress could
increase the soluble sugar contents in wheat and barley (Yang et al.,
2009). Evidence to support this trend can be obtained from the results of
this investigation which demonstrate that, in most cases, NaCl or Na2CO3
at the two applied phases had a significant stimulatory effect on the
accumulation of glucose and fructose in shoots of the test plants. It is
worth to mention that, in jojoba plant, the biosynthesis of glucose was
consistently higher than fructose. The accumulation of soluble sugar has
been considered as an adaptive response to stresses (Thomas, 1999). This
phenomenon is associated with osmotic adjustment, which occurs in
many plant species (Asish et al., 2002). In this respect, Morsy et al.
(2007) concluded that chilling-tolerant genotype endure low level of
oxidative stress products, and accumulates higher levels of sugar
metabolites, which display an important role in osmoregulation and
46
Radi A. A., Farghaly F. A., Abdel-Wahab D. A., and Hamada A. M.
membrane stabilization. An increase in soluble sugar content in response
to alkali stress was also detected in barley and sunflower (Yang et al.,
2009; Liu et al., 2010). On the other hand, accumulation of glucose and
fructose was not correlated with a specific stress tolerance, and the
observed variations in the endogenous content of monosacchrides might
be due to slowdown in sugar transfer from the mesophyll cells to phloem
(Jouve et al., 2004). However, a high hexose level is required as a driving
force to lower cell water potential and maintain turgor pressure (Sturm,
1999).
Protein synthesis has been considered as a possible primary target
of salt toxicity because in vitro protein synthesis systems are dependent
on physiological K+ and are inhibited by Na+ and Cl-(Morant-Avice et al.,
1998). Considering the evidences on plant soluble protein response to
salinity, there is a marked difference among the species and varieties. The
data herein obtained show that NaCl and Na2CO3, at the two applied
phases, had an inhibitory effect on the accumulation of soluble proteins in
shoots of the test plants. It is interesting to note that soluble proteins were
much higher in jojoba shoots compared with the sunflower ones.
Furthermore, there was positive moderate correlation between K+ and
soluble proteins in shoots of both test plants, while this correlation was
strong negative with Na+. In general, salt stress results in a reduction of
soluble proteins contents, which are often due to an inhibition of their
synthesis and/or the increase of their hydrolysis (Irigoyen et al., 1992).
However, these results were accompanied with the pronounced
accumulation of free amino acids in leaves and roots of both test plants.
This indicate that the reduction in proteins might be due to accelerated
proteolases that hydrolyse proteins into amino acids (Irigoyen et al.,
1992) and/or denaturation of enzymes involved in proteins synthesis as a
result of salinity stress (Jaleel et al., 2007; Lakhdar et al., 2008). One may
speculate that, salt tolerant cultivars producing higher protein
concentration is due to higher efficiency of osmotic regulation
mechanism, which in turn causes decreasing sodium toxicity in cytoplasm
compared to susceptible ones and the result is to prevent proteins
reduction under salt stress (Flowers and Yeo, 1992).
Proline accumulation is a universal plant response to stress. Our
results clearly showed a significant increase in proline accumulation in
the test plants; however the accumulation was greater in sunflower when
the salinity or alkalinity increased. The same trend was reported in canola
(Saadia et al., 2012), rice callus tissue (Kumar et al., 2010) and
sunflower. Silva-Ortega et al. (2008) suggested that leaves accumulate
Physiological and Metabolic Responses of Two Oil- Producing Plants to Salt…. 47
more proline in order to maintain chlorophyll level and cell turgor to
protect photosynthetic activity under salt stress. Proline accumulation is
primarily caused by activation of proline synthesis via the glutamate
pathway, while depression of proline degradation also serves to increase
proline levels (Huang et al., 2013). Also, DNA methylation
(demethylation) as a result of osmotic stress facilitate proline
accumulation via the up-regulation of proline metabolism-related gene
expression (Zhang et al., 2013).
Besides proline, the involvement of other amino acids in response
to osmotic stress also demonstrated. The data reached in the present work
show elevated amino acids levels in leaves of jojoba and sunflower under
saline or alkaline stress, these results agree with Kovács et al. (2012) who
concluded that an elevation in the amino acid content is involved in both
the short- and long-term response to osmotic stress. It has been shown
that increased alanine aminotransferase (AlaAT) and aspartate
aminotransferase (AspAT) activities are observed in some plant species
under salt and heavy metal stress (Surabhi et al., 2008). Increased AlaAT
and AspAT may mediate the utilization of ammonia by converting
ketoacids into amino acids under stress conditions, which would further
help coordinate N metabolism and amino acid synthesis with the
availability of carbon skeletons from the Krebs cycle (Hodges, 2002). In
this respect, NaCl treatment may lead to a significant decrease in NO3and N organic concentrations and growth inhibition (Gao et al., 2013). It
was suggested that NaCl stress may decrease the activity of nitrate
reductase and nitrite reductase, induce the glutamine synthetase/glutamate
synthase cycle and glutamate dehydrogenase pathways for NH4+
assimilation, and increase aminotransferase activities to meet an increased
demand for amino acids under stressful conditions.
Significant differential responses to salinity or alkalinity were
displayed by the two test plants. Jojoba was less susceptible to salinity
and alkalinity compared to sunflower. The results herein obtained show
that NaCl and Na2CO3 treatments lead to a significant decrease in growth
index of jojoba and sunflower plants. The reduction could be ascribed to
the reduction in synthesis of plant pigments and the increased level of the
toxic Na+cation and decreased K+ ion. The applied salts lead to enhance
synthesis of osmoprotectant metabolites, glucose, fructose, proline and
other amino acids.
In conclusion, the differential responses to salt stress exhibited by the
experimental plants could be generally attributed to the ionic and
48
Radi A. A., Farghaly F. A., Abdel-Wahab D. A., and Hamada A. M.
metabolic alterations for maintaining the integrity of cellular adaptations
achieved for salt tolerance mechanisms.
REFERENCES
Abbas, W. ,Ashraf, M. and Akram, N.A. (2010): Alleviation of salt-induced
adverse effects in eggplant (Solanum melongena) by glycinebetaine and
sugarbeet extracts, Scientia horticaculturae. 125: 188-195.
Akram, M. ,Ashraf, M. ,Ahmad, R. ,Rafiq, M. ,Ahmad, I. and Iqbal, J. (2010):
Allometry and yield components of maize (Zea mays L.) hybrids to
various potassium levels under saline conditions, Archives of Biological
Sciences. 62: 1053-1061.
Akram, M.S. and Ashraf, M. (2011): Exogenous application of potassium dihydrogen
phosphate can alleviate the adverse effects of salt stress on sunflower
(Helianthus annuus L.), Journal of plant nutrition. 34: 1041-1057.
Akram, N.A. ,Ashraf, M. and Al-Qurainy, F. (2012): Aminolevulinic acidinduced changes in some key physiological attributes and activities of
antioxidant enzymes in sunflower (Helianthus annuus L.) plants under
saline regimes, Scientia horticaculturae. 142: 143-148.
Allen, S.E. (1989): Chemical Analysis of Ecological Materials (2nd
ed.).Blackwell Scientific Publications, Oxford., Pp 368.
Anil, V.S. ,Krishnamurthy, H. and Mathew, M. (2007): Limiting cytosolic Na+
confers salt tolerance to rice cells in culture: a two-photon microscopy
study of SBFI-loaded cells, Physiologia Plantarum. 129: 607-621.
Ashraf, M. ,Akram, N. ,Al-Qurainy, F. and Foolad, M. (2011): Drought
tolerance: Roles of organic osmolytes, growth regulators, and mineral
nutrients, Advances in Agronomy. 111: 249-296.
Ashraf, M. and Harris, P. (2013): Photosynthesis under stressful environments:
An overview, Photosynthetica. 51: 163-190.
Ashraf, M. and Tufail, M. (1995): Variation in salinity tolerance in sunflower
(Helianthus annum L.), Journal of agronomy crop science 174: 351-362.
Asish, P. ,Anath, B.D. and Premananda, D. (2002): NaCl stress causes changes
in photosynthetic pigments, proteins, and other metabolic components in
the leaves of a true mangrove, Bruguiera parviflora, in hydroponic
cultures, Journal of Plant Biology 45: 28-36.
Bates, L. ,Waldren, R. and Teare, I. (1973): Rapid determination of free proline
for water stress studies, Plant and Soil. 39: 205-207.
Bergqvist, C. and Greger, M. (2012): Arsenic accumulation and speciation in
plants from different habitats, Application Geochemistry. 27: 615-622.
Canoira, L. ,Alcántara, R. ,Jesús García-Martínez, M. and Carrasco, J. (2006):
Biodiesel from Jojoba oil-wax: Transesterification with methanol and
properties as a fuel, Biomass and Bioenergy. 30: 76-81.
Cardarelli, M. ,Rouphael, Y. ,Rea, E. and Colla, G. (2010): Mitigation of
alkaline stress by arbuscular mycorrhiza in zucchini plants grown under
Physiological and Metabolic Responses of Two Oil- Producing Plants to Salt…. 49
mineral and organic fertilization, Journal of plant nutrition and soil
science. 173: 778-787.
Cha-um, S. ,Charoenpanich, A. ,Roytrakul, S. and Kirdmanee, C. (2009): Sugar
accumulation, photosynthesis and growth of two indica rice varieties in
response to salt stress, Acta physiologiae plantarum. 31: 477-486.
Chen, H.-J. ,Chen, J.-Y. and Wang, S.-J. (2008): Molecular regulation of starch
accumulation in rice seedling leaves in response to salt stress, Acta
physiologiae plantarum. 30: 135-142.
Cramer, G. ,Alberico, G. and Schmidt, C. (1994): Salt tolerance is not associated
with the sodium accumulation of two maize hybrids, Functional Plant
Biology. 21: 675-692.
Cuartero, J. ,Bolarin, M. ,Asins, M. and Moreno, V. (2006): Increasing salt
tolerance in the tomato, Journal of Experimental Botany. 57: 1045-1058.
Daneshmand, F. ,Arvin, M.J. and Kalantari, K.M. (2010): Physiological
responses to NaCl stress in three wild species of potato in vitro, Acta
Physiologiae Plantarum. 32: 91-101.
Di Caterina, R. ,Giuliani, M. ,Rotunno, T. ,De Caro, A. and Flagella, Z. (2007):
Influence of salt stress on seed yield and oil quality of two sunflower
hybrids, Annals of Applied Biology. 151: 145-154.
FAO (2010): Area harvested and production of oilseed crops., In FAO statistical
yearbook 2010.
Farkhondeh, R. ,Nabizadeh, E. and Jalilnezhad, N. (2012): Effect of salinity stress on
proline content, membrane stability and water relations in two sugar beet
cultivars, International Journal of Agricultural Science. 2: 385-392.
Flowers, T. (2004): Improving crop salt tolerance, Journal of Experimental
Botany. 55: 307-319.
Flowers, T.J. and Yeo, A. (1992): Solute transport in plants. Blackie academic &
professional
Foyer, C.H. and Shigeoka, S. (2011): Understanding oxidative stress and antioxidant
functions to enhance photosynthesis, Plant physiology. 155: 93-100.
Gao, S. ,Liu, K.T. ,Chung, T.W. and Chen, F. (2013): The effects of NaCl stress
on Jatropha cotyledon growth and nitrogen metabolism, Journal of soil
science and plant nutrition. 13 99-113.
Genc, Y. ,Mcdonald, G.K. and Tester, M. (2007): Reassessment of tissue Na+
concentration as a criterion for salinity tolerance in bread wheat, Plant,
Cell & Environment. 30: 1486-1498.
Gould, K. ,McKelvie, J. and Markham, K. (2002): Do anthocyanins function as
antioxidants in leaves? Imaging of H2O2 in red and green leaves after
mechanical injury, Plant, Cell & Environment. 25: 1261-1269.
Gupta, A.K. and Kaur, N. (2005): Sugar signalling and gene expression in
relation to carbohydrate metabolism under abiotic stresses in plants,
Journal of biosciences. 30: 761-776.
Hagemeyer, J. (1997): Salt, John Wiley & Sons, Inc., New York.
50
Radi A. A., Farghaly F. A., Abdel-Wahab D. A., and Hamada A. M.
Halhoul, M. and Kleinberg, I. (1972): Differential determination of glucose and
fructose, and glucose-and fructose-yielding substances with anthrone,
Analytical biochemistry. 50: 337-343.
Haq, T. ,Akhtar, J. ,Nawaz, S. and Ahmad, R. (2009): Morpho-physiological
response of rice (Oryza sativa L.) varieties to salinity stress, Pakistian
Journal of Botany. 41: 2943-2956.
Heidari, A. ,Toorchi, M. ,Bandehagh, A. and Shakiba, M.R. (2011): Effect of
NaCl stress on growth, water relations, organic and inorganic osmolytes
accumulation in sunflower (Helianthus annuus L.) lines, Universal
Journal of Environmental Research and Technology. 1: 351-362.
Hoagland, D.R. and Arnon, D.I. (1950): The water-culture method for growing plants
without soil, Circular. California Agricultural Experiment Station. 347.
Hodges, M. (2002): Enzyme redundancy and the importance of 2-oxoglutarate in plant
ammonium assimilation, Journal of Experimental Botany. 53: 905-916.
Horie, T. ,Karahara, I. and Katsuhara, M. (2012): Salinity tolerance mechanisms in
glycophytes: An overview with the central focus on rice plants, Rice. 5: 1-18.
Hu, Y. ,Burucs, Z. and Schmidhalter, U. (2012): Short term effect of drought
and salinity on growth and mineral elements in wheat seedlings, Journal
of Plant Nutrition. 29: 2227-2243.
Huang, Z. ,Zhao, L. ,Chen, D. ,Liang, M. ,Liu, Z. ,Shao, H. and Long, X. (2013):
Salt stress encourages proline accumulation by regulating proline
biosynthesis and degradation in Jerusalem Artichoke plantlets, PLoS
One. 8: e62085.
Hussain, I. ,Iqbal, M. ,Nawaz, M. ,Rasheed, R. ,Perveen, A. ,Mahmood, S.
,Yasmeen, A. and Wahid, A. (2013): Effect of Sugar Mill Effluent on
Growth and Antioxidative Potential of Maize Seedling, International
Journal of Agriculture & Biology. 15: 1227-1235.
Hussain, M. ,Farooq, M. ,Basra, S.M. and Ahmad, N. (2006): Influence of seed
priming techniques on the seedling establishment, yield and quality of hybrid
sunflower, International Journal of Agriculture and Biology. 8: 14-18.
IJEC (2008): The International Jojoba Export Council.
I rigoyen, J. ,E inerich, D. and Sánchez- Diaz, M. (1992): Water stress induced
changes in concentrations of proline and total soluble sugars in nodulated
alfalfa (Medicago sativa) plants, Physiologia Plantarum. 84: 55-60.
Jaleel, C.A. ,Manivannan, P. ,Lakshmanan, G.M.A. ,Sridharan, R. and
Panneerselvam, R. (2007): NaCl as a physiological modulator of proline
metabolism and antioxidant potential in Phyllanthus amarus, Comptes
rendus biologies. 330: 806-813.
Jha, D. ,Shirley, N. ,Tester, M. and Roy, S.J. (2010): Variation in salinity
tolerance and shoot sodium accumulation in Arabidopsis ecotypes
linked to differences in the natural expression levels of transporters
involved in sodium transport, Plant, Cell & Environment. 33: 793-804.
Jouve, L. ,Hoffmann, L. and Hausman, J.F. (2004): Polyamine, carbohydrate,
and proline content changes during salt stress exposure of aspen
Physiological and Metabolic Responses of Two Oil- Producing Plants to Salt…. 51
(Populus tremula L.): involvement of oxidation and osmoregulation
metabolism, Plant Biology. 6: 74-80.
Kader, M.A. ,Lindberg, S. ,Seidel, T. ,Golldack, D. and Yemelyanov, V. (2007):
Sodium sensing induces different changes in free cytosolic calcium
concentration and pH in salt-tolerant and -sensitive rice (Oryza sativa)
cultivars, Physiologia Plantarum. 130: 99-111.
Katerji, N. ,Van Hoorn, J. ,Hamdy, A. and Mastrorilli, M. (2000): Salt tolerance
classification of crops according to soil salinity and to water stress day
index, Agricultural Water Management. 43: 99-109.
Khatoon, S. ,Rai, V. ,Rawat, A.K. and Mehrotra, S. (2006): Comparative
pharmacognostic studies of three Phyllanthus species, Journal of
Ethnopharmacology. 104: 79-86.
Kovács, Z. ,Simon-Sarkadi, L. ,Vashegyi, I. and Kocsy, G. (2012): Different
Accumulation of Free Amino Acids during Short-and Long-Term
Osmotic Stress in Wheat, The Scientific World Journal. 2012: 1-10.
Kukreja, S. ,Nandwal, A. ,Kumar, N. ,Sharma, S. ,Unvi, V. and Sharma, P.
(2005): Plant water status, H2O2 scavenging enzymes, ethylene
evolution and membrane integrity of Cicer arietinum roots as affected
by salinity, Biologia plantarum. 49: 305-308.
Kumar, V. ,Shriram, V. ,Kishor, P.K. ,Jawali, N. and Shitole, M. (2010):
Enhanced proline accumulation and salt stress tolerance of transgenic
indica rice by over-expressing P5CSF129A gene, Plant Biotechnology
Reports. 4: 37-48.
Kytridis, V.-P. and Manetas, Y. (2006): Mesophyll versus epidermal
anthocyanins as potential in vivo antioxidants: evidence linking the
putative antioxidant role to the proximity of oxy-radical source, Journal
of Experimental Botany. 57: 2203-2210.
Lakhdar, A. ,Hafsi, C. ,Rabhi, M. ,Debez, A. ,Montemurro, F. ,Abdelly, C.
,Jedidi, N. and Ouerghi, Z. (2008): Application of municipal solid waste
compost reduces the negative effects of saline water in Hordeum
maritimum L, Bioresource technology. 99: 7160-7167.
Li, T.Y. ,Zhang, Y. ,Liu, H. ,Wu, Y. ,Li, W. and Zhang, H. (2010): Stable
expression of Arabidopsis vacuolar Na+/H+ antiporter gene AtNHX1,
and salt tolerance in transgenic soybean for over six generations,
Chinese Science Bulletin. 55: 1127-1134.
Lichtenthaler, H.K. (1987): Chlorophylls and carotenoids: Pigments of
photosynthetic biomembranes, Methods in enzymology. 148: 350-382.
Liu, J. ,Guo, W. and Shi, D. (2010): Seed germination, seedling survival, and
physiological response of sunflowers under saline and alkaline
conditions, Photosynthetica. 48: 278-286.
Lowery, O., Rosebrough, N., Farr, A. and Randall, R. (1951): Protein
maesurment with the Folin phenol reagent , The Journal of Biological
Chemistry . 193:256-275.
52
Radi A. A., Farghaly F. A., Abdel-Wahab D. A., and Hamada A. M.
MALR (2009): Ministry of Agriculture and Land.Reclamation.Agriculture
Statistic "brief". Center Administration of Agriculture Economics.
Mancinelli, A.L. (1990): Interaction between light quality and light quantity in the
photoregulation of anthocyanin production, Plant Physiology. 92: 1191-1195.
Merzlyak, M.N. ,Chivkunova, O.B. ,Solovchenko, A.E. and Naqvi, K.R. (2008):
Light absorption by anthocyanins in juvenile, stressed, and senescing
leaves, Journal of Experimental Botany. 59: 3903-3911.
Mills, D. and Benzioni, A. (1992): Effect of NaCl Salinity on Growth and
Development of Jojoba Clones: 11. Nodal Segments Grown in Vitro,
Journal of Plant Physiology. 139: 737-741.
Mills, D. ,Wenkart, S. and Benzioni, A. (1997). Micropropagation of
Simmondsia chinensis (Jojoba). High-Tech and Micropropagation VI.
In: Bajaj. Springer-Verlag,Berlin. 40: 370–393.
Mills, D. ,Zhang, G. and Benzioni, A. (2001): Effect of different salts and of
ABA on growth and mineral uptake in Jojoba shoots grown in vitro,
Journal of Plant Physiology. 158: 1031-1039.
Mohamedin, A. ,Awaad, M. and Ahmed, A.R. (2010): The negative role of soil
salinity and waterlogging on crop productivity in the northeastern region
of the Nile Delta, Egypt, Research Journal of Agriculture and Biological
Sciences. 6: 378-385.
Moore, S. and Stein, W.W. (1948): Amino acid free photometric ninhydrin
method for use in chromatography of amino acids, Journal of biological
chemistry. 176: 367-388.
Morant-Avice, A. ,Pradier, E. and Houchi, R. (1998): Osmotic adjustment in
triticales grown in presence of NaCl, Biologia plantarum. 41: 227-234.
Morgan, S.H. ,Lindberg, S. and Mühling, K.H. (2013): Calcium supply effects
on wheat cultivars differing in salt resistance with special reference to
leaf cytosol ion homeostasis, Physiologia Plantarum.
Morsy, M.R. ,Jouve, L. ,Hausman, J.-F. ,Hoffmann, L. and Stewart, J.M. (2007):
Alteration of oxidative and carbohydrate metabolism under abiotic stress
in two rice (Oryza sativa L.) genotypes contrasting in chilling tolerance,
Journal of Plant Physiology. 164: 157-167.
Munns, R. (2002): Comparative physiology of salt and water stress, Plant Cell
Environ. 25: 239-250.
Munns, R. and Tester, M. (2008): Mechanisms of salinity tolerance, Annual
Review of Plant Biology. 59: 651-681.
Oren-Shamir, M. (2009): Does anthocyanin degradation play a significant role in
determining pigment concentration in plants?, Plant Science. 177: 310-316.
Premachandra, G.S. ,Saneoka, A.H. ,Fujta, K. and Ogata, S. (1992): Leaf water
relations, osmotic adjustment, cell membrane stability, epicuticular wax
load and growth as affected by increasing water deficits in sorghum,
Journal of Experimental Botany. 43: 1569-1576.
Physiological and Metabolic Responses of Two Oil- Producing Plants to Salt…. 53
Rajendran, K. ,Tester, M. and Roy, S.J. (2009): Quantifying the three main
components of salinity tolerance in cereals, Plant, Cell & Environment.
32: 237-249.
Rana, M.Y. ,Bashir, M.A. ,Asad, M.N. and Iqbal, A.M. (2003): Effects of
various agro-climatic factors on germination and growth of jojoba in
Pakistan, Pakistan Journal of Biological Sciences. 6: 1447-1449.
Rauf, S. ,Munir, H. and Sadaqat, H.A. (2008 ): Growing sunflower with
insufficient water, Money Plus. 16-17.
Rauf, S. ,Sadaqat, H. ,Khan, I. and Ahmed, R. (2009): Genetic analysis of leaf
hydraulics in sunflower (Helianthus annuus L.) under drought stress,
Plant, Cell and Environment. 55: 62-69.
Rauf, S. and Sadaqat, H.A. (2008): Effect of osmotic adjustment on root length
and dry matter partitioning in sunflower (Helianthus annuus L.) under
drought stress, Acta Agriculturae Scandinavica Section B–Soil and Plant
Science. 58: 252-260.
Saadia, M. ,Jamil, A. ,Akram, N.A. and Ashraf, M. (2012): A study of proline
metabolism in Canola (Brassica napus L.) seedlings under salt stress,
Molecules. 17: 5803-5815.
Santos, C.L. and Caldeira, G. (1999): Comparative Responses of Helianthus annuus
Plants and Calli Exposed to NaCl: I. Growth Rate and Osmotic Regulation in
Intact Plants and Calli, Journal of Plant Physiology. 155: 769-777.
Saqib, M. ,Zörb, C. and Schubert, S. (2006): Salt-resistant and salt-sensitive
wheat genotypes show similar biochemical reaction at protein level in
the first phase of salt stress, Journal of Plant Nutrition and Soil Science.
169: 542-548.
Senadheera, P. ,Singh, R. and Maathuis, F.J. (2009): Differentially expressed
membrane transporters in rice roots may contribute to cultivar dependent
salt tolerance, Journal of Experimental Botany. 60: 2553-2563.
Seydi, A. B., Hassan, E. K. and Yilmaz, Z. A. (2003): Determination of the salt
tolerance of some barley genotypes and the characteristics affecting
tolerance, Turkish Journal of Agriculture& Forestry. 27: 253-260
Shahbaz, M. ,Ashraf, M. ,Akram, N. ,Hanif, A. ,Hameed, S. ,Joham, S. and
Rehman, R. (2010): Salt-induced modulation in growth, photosynthetic
capacity, proline content and ion accumulation in sunflower (Helianthus
annuus L.), Acta Physiologiae Plantarum. 33: 1113-1122.
Shaheen, S. ,Naseer, S. ,Ashraf, M. and Akram, N.A. (2013): Salt stress affects
water relations, photosynthesis, and oxidative defense mechanisms in
Solanum melongena L, Journal of Plant Interactions. 8: 85-96.
Shi, D. and Sheng, Y. (2005): Effect of various salt–alkaline mixed stress
conditions on sunflower seedlings and analysis of their stress factors,
Environmental and Experimental Botany. 54: 8-21.
Shvarts, M. ,Borochov, A. and Weiss, D. (1997): Low temperature enhances
petunia flower pigmentation and induces chalcone synthase gene
expression, Physiologia Plantarum. 99: 67-72.
54
Radi A. A., Farghaly F. A., Abdel-Wahab D. A., and Hamada A. M.
Silva-Ortega, C.O. ,Ochoa-Alfaro, A.E. ,Reyes-Agüero, J.A. ,Aguado-Santacruz,
G.A. and Jiménez-Bremont, J.F. (2008): Salt stress increases the
expression of p5cs gene and induces proline accumulation in cactus
pear, Plant Physiology and Biochemistry. 46: 82-92.
Siringam, K. ,Juntawong, N. ,Cha-um, S. and Kirdmanee, C. (2011): Salt stress
induced ion accumulation, ion homeostasis, membrane injury and sugar
contents in salt-sensitive rice (Oryza sativa L. spp. indica) roots under
isoosmotic conditions, African Journal of Biotechnology. 10: 1340-1346.
Sturm, A. (1999): Invertases. Primary structures, functions, and roles in plant
development and sucrose partitioning, Plant physiology. 121: 1-8.
Surabhi, G.-K. ,Reddy, A.M. ,Kumari, G.J. and Sudhakar, C. (2008): Modulations in
key enzymes of nitrogen metabolism in two high yielding genotypes of
mulberry (Morus alba L.) with differential sensitivity to salt stress,
Environmental and Experimental Botany. 64: 171-179.
Tang, J. ,Yu, X. ,Luo, N. ,Xiao, F. ,Camberato, J.J. and Jiang, Y. (2013): Natural
variation of salinity response, population structure and candidate genes
associated with salinity tolerance in perennial ryegrass accessions, Plant,
Cell & Environment.
Thomas, R. (1999): Source-sink regulation by sugar and stress, Current opinion
in plant biology. 2: 198-206.
Tremper, G. (1996): The history and premises of Jojoba, Jojoba Obispo, Los
Angeles, California, USA.
Tunuturk, M. ,Tuncturk, R. ,Yildirim, B. and Çiftçi, V. (2011): Effect of salinity stress
on plant fresh weight and nutrient composition of some Canola (Brassica
napus L.) cultivars, African Journal of Biotechnology. 10: 1827-1832.
Wahome, P. (2003). Mechanisms of salt (NaCl) stress tolerance in horticultural
crops-a mini review. International Symposium on Managing
Greenhouse Crops in Saline Environment 609.
Williams, V. and Twine, S. (1960): Flame photometric method for sodium,
potassium and calcium.In: Peach, K. and M.V. Tracey (eds.), Modern
Methods of Plant Analysis. 5: 3-5.
Yang, C. ,Chong, J. ,Li, C. ,Kim, C. ,Shi, D. and Wang, D. (2007): Osmotic
adjustment and ion balance traits of an alkali resistant halophyte Kochia
sieversiana during adaptation to salt and alkali conditions, Plant and
Soil. 294: 263-276.
Yang, C.W. ,Xu, H.H. ,Wang, L.L. ,Liu, J. ,Shi, D.C. and Wang, D.L. (2009):
Comparative effects of salt-stress and alkali-stress on the growth,
photosynthesis, solute accumulation, and ion balance of barley plants,
Photosynthetica. 47: 79-86.
Zhang, L. ,Zhang, G. ,Wang, Y. ,Zhou, Z. ,Meng, Y. and Chen, B. (2013): Effect
of soil salinity on physiological characteristics of functional leaves of
cotton plants, Journal of Plant Research. 1-12.
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‫‪Physiological and Metabolic Responses of Two Oil- Producing Plants to Salt…. 55‬‬
‫استجابات فسيولوجية وايضية لالجهاد الملحى والقلوى فى نباتين منتجين للزيوت‬
‫عبير أحمد فرج راضى*‪ ،‬فاطمة على فرغلى* ‪ ,‬داليا أحمد محمد عبد الوهاب**‪،‬‬
‫*‬
‫عفاف محمد حمادة‬
‫* قسم النبات والميكروبيولوجى‪ -‬كلية العلوم – جامعة أسيوط ‪ -‬أسيوط‪.‬‬
‫** قسم النبات ‪ -‬كلية العلوم ‪ -‬جامعة أسيوط ‪ -‬الوادى الجديد‪.‬‬
‫ملوحة التربة وقلويتها من أهم وأخطر المشاكل البيئية التى تتمركز بوجه‬
‫خاص فى المناطق الجافة‪ -‬شبه الجافة‪ -‬شديدة الحرارة وهو األمر الذى ينعكس‬
‫سلبيا على نمو النباتات وبالتالى انتاجيته‪ .‬وعليه فقد أجرى البحث امتداد للدراسات‬
‫ذات الصلة بهذه المشكلة والتى تتناول دراسة مدى التكيف والتحوط المستحث فى‬
‫نباتين منتجين للزيوت (الجوجوبا وعباد الشمس) اذا ما تعرضا ابان نموهما المبكر‬
‫الى اجهاد ملحى أو قلوى لمتابعة بعض التغيرات الفسيولوجية واأليضية التى يمكن‬
‫أن يكون لها مردودا خاصا فى أقلمة النباتين قيد البحث وتكيفهما للمتغيرات ذات‬
‫الصلة بملوحة وقلوية الوسط الغذائى باستخدام تركيزات معينة من ملحى كلوريد‬
‫وكربونات الصوديوم‪.‬‬
‫وقد أوضحت نتائج هذا البحث أن زيادة مستوى كل من الملحين فى الوسط‬
‫الغذائى يؤدى الى نقص ملحوظ فى‪:‬‬
‫(‪ )1‬معامل تحمل الملوحة (‪)STI‬‬
‫)‪ (2‬مكونات اختضاب النبات باالضافة الى االنثوسيانين والبروتينات الذائبة‬
‫ومعامل تراكم الصوديوم (‪ )SAF‬فى المجموعين الخضرى والجذرى لكل‬
‫من النباتين قيد الدراسة وقد كان النقص فى هذه المعايير جليا عند المستوى‬
‫األعلى (‪ )Toxic phase‬ألى من الملحين المستخدمين‪.‬‬
‫وعلى الجانب األخر لوحظ أن تركيز أيونات الصوديوم وكذلك نسبة ايونات‬
‫الصوديوم ‪ /‬البوتاسيوم فى المجموعين الخضرى والجذرى ألى من النباتين قيد‬
‫البحث قد ازداد بزيادة مستوى الملحين‪ .‬وقد أوضحت النتائج أيضا زيادة ارتشاح‬
‫أيونات الصوديوم والبوتاسيوم من أوراق النباتات المعاملة لكل من الملحين بزيادة‬
‫مستوى أى منهما فى الوسط الغذائى ‪.‬‬
‫الى جانب ذلك أشارت النتائج الى زيادة تخليق وتراكم كل من الجلوكوز‬
‫والفركتوز والبرولين وغيره من األحماض األمينية الحرة فى نباتات المعاملة‬
‫بالملحين المستخدمين‪ .‬ومن الجدير بالذكر أن نباتات عباد الشمس كانت أكثر‬
‫حساسية لمعامالت الملوحة والقلوية من نظيره الجوجوبا‪.‬‬