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Scientia Horticulturae 125 (2010) 188–195

Contents lists available at ScienceDirect

Scientia Horticulturae

journa l homepage: www.e lsev ier .com/ locate /sc ihor t i

lleviation of salt-induced adverse effects in eggplant (Solanum melongena L.) bylycinebetaine and sugarbeet extracts

asim Abbasa, Muhammad Ashrafa,b, Nudrat Aisha Akrama,∗

Department of Botany, University of Agriculture, Faisalabad, PakistanKing Saud University, Riyadh, Saudi Arabia

r t i c l e i n f o

rticle history:eceived 16 January 2010eceived in revised form 2 April 2010ccepted 4 April 2010

eywords:alt stressggplantlycinebetaine

a b s t r a c t

Two eggplant cultivars, Dilnasheen and Bemisal, were selected to assess whether pure GB and sugarbeetextract could effectively ameliorate the harmful effects of salt stress on eggplant (Solanum melongenaL.), under saline conditions. Salt stress markedly suppressed the growth, yield, photosynthetic capacity,internal CO2 level, transpiration, and stomatal conductance in both cultivars. Potassium (K+) and Ca2+

contents and K+/Na+ ratios of both root and leaf were also reduced, while GB and proline in leaves, andNa+ and Cl− contents in roots and leaves were significantly enhanced. Exogenously applied glycinebe-taine and sugarbeet extracts significantly counteracted the salt-induced adverse effects on growth, yield,various gas exchange characteristics, GB and leaf K+, Ca+, Cl− and Na+. However, GB and sugarbeet extract

as exchange characteristicsineral nutrients

showed differential effects on photosynthetic rate, stomatal conductance and transpiration, internal CO2

level, Ci/Ca ratio, leaf K+, Ca2+, and Cl− contents, and K+/Na+ ratio. Sugarbeet extract proved better than theGB in improving growth, photosynthetic rate, transpiration, stomatal conductance, yield and GB accu-mulation. Since, sugarbeet extract contains a substantial amount of GB along with a variety of otherimportant nutrients so it was found as effective as pure GB in improving growth and some key physio-logical processes in eggplant under salt stress. Thus, it can be used as an alternative cheaper source of GB

tive a

for its use as an ameliora

. Introduction

Glycinebetaine, an amino acid derivative, is naturally found inicroorganisms, plants, and animals (Sakamoto and Murata, 2002;akela, 2004). It occurs abundantly in many crop plants including

pinach (Weigel et al., 1986), wheat (McDonnell and Wyn Jones,988), alfalfa (Wood et al., 1991), and bean (Gadallah, 1999). How-ver, many important crop plants, like maize, potato, tomato, andggplant are unable to accumulate glycinebetaine (Zwart et al.,003). Glycinebetaine was first discovered in sugarbeet (Beta vul-aris) juice at the rate of 100 mmol kg−1 plant tissue (Mack et al.,007). It physiologically acts as an osmolyte to protect cells or ascatabolic source of methyl groups to facilitate various biochem-

cal processes (Craig, 2004). It can protect the plant cells againstsmotic inactivation and increases the water retention of cellsLiu and Bolen, 1995; Sakamoto and Murata, 2002; Makela, 2004;

shraf and Foolad, 2007). However, exposure to salt stress triggerslycinebetaine synthesis in cell chloroplasts of most plant speciesRathinasabapathi et al., 1997; Park et al., 2007) and glycinebetaine-nduced improvement in plant is widely reported (Ashraf et al.,

∗ Corresponding author. Tel.: +92 41 9200312; fax: +92 41 9201078.E-mail address: nudrataauaf@yahoo.com (N.A. Akram).

304-4238/$ – see front matter © 2010 Elsevier B.V. All rights reserved.oi:10.1016/j.scienta.2010.04.008

gent for protecting plants against the hazardous effects of salt stress.© 2010 Elsevier B.V. All rights reserved.

2008; Mahmood et al., 2009; Nawaz and Ashraf, 2009). For example,with exogenous application of GB, improvement in salt tolerancehad been achieved in different crops, e.g., tomato (Mäkela et al.,1998), cotton (Naidu, 1998), rice (Rahman et al., 2002), Triticum aes-tivum (Raza et al., 2007; Mahmood et al., 2009), and maize (Nawazand Ashraf, 2009). In almost all studies wherein GB has been shownas an effective ameliorating agent against salt or other stressesreported so far in the literature, pure GB procured from the knownchemical manufacturing companies has been used.

Vegetable crops are very important due to their higheryield potential, low production cost and higher nutritional value(Mukerji, 2004; Noreen and Ashraf, 2009a,b). Eggplant (S. melon-gena L.), known as brinjal, aubergine or Guinea squash is cultivatedon more than 1.5 Mha in the world (Kantharajah and Golegaonkar,2004). Nutritionally, eggplant is as tomato, because both are a richsource of vitamins and minerals (Kalloo and Bergh, 1993). How-ever, eggplant is moderately sensitive to salinity (Heuer et al., 1986;Savvas and Lenz, 1996; Akinci et al., 2004). Extensive researchhas been carried out to examine salt-induced morphological, bio-

chemical and physiological changes in eggplant (Chartzoulakis andLoupassaki, 1997; Hamdy et al., 2002; Akinci et al., 2004). How-ever, information on the alleviation of salt-induced adversaries byfoliar applied GB in eggplant is lacking. Of many naturally GB-accumulating plants (Ashraf and Foolad, 2007), sugarbeet is known

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o accumulate a substantial amount of GB (100 mmol/kg plant tis-ue) (Mack et al., 2007), or 0.2–0.3% (Korteniemi, 2007). In additiono it, 100 g sugarbeet extract contains a variety of other inorganicutrients and organic compounds such as fiber (2.8 g), carbohy-rates (9.56 g), calcium (16 mg), potassium (325 mg), magnesium23 mg), phosphorus (40 mg), vitamin E (0.3 mg), and vitamin

(4.9 mg) (http://www.botanical-online.com/commonbeet.htm).owever, information on the exogenous application of this naturalB source in alleviating the salt-induced adverse effects cannot beeciphered from the literature.

So, we hypothesized that foliar applied pure GB or GB-enrichedugarbeet extract could effectively minimize salt-induced harm-ul effects on growth of eggplant, naturally a GB-non-accumulator.hus, the two principal objectives of carrying out this study were: (i)hether or not exogenous application of GB could protect eggplant

gainst salt stress, and (ii) how effective the sugarbeet extract is inegulating growth and some key physiological processes involvedn salt tolerance of eggplant as compared to the pure GB.

. Materials and methods

A greenhouse experiment was conducted in the Botanical Gar-en, University of Agriculture, Faisalabad, to examine the plausibleole of foliar-applied glycinebetaine and sugarbeet extract to min-mize the growth loss in eggplant (S. melongena L.) caused by NaCl.uring experimentation, two eggplant cultivars, Bemisal and Dil-asheen were subjected to two NaCl treatments, i.e., 0 mM (control)nd 100 mM. Eight seed of each of the two cultivars were sownn sand (10 kg) contained in plastic pots. Two liters of Hoagland’sutrient solution (full strength) were applied weekly to each pot.xperiment was arranged in a completely randomized designith four replicates. Ten days after seed germination, plants were

hinned to five in each pot/replicate, and after 30 days, NaCl treat-ents were begun. Different concentrations of GB (0, 50 mM pureB, prepared in 0.1% (v/v) Tween-20 and sugarbeet extract contain-

ng 50 mM GB were used for exogenous application. GlycinebetaineM. wt. = 117.1) of Sigma–Aldrich, Japan was used. For the extrac-ion of sugarbeet juice, fresh sugarbeet roots were procured fromhe local market. After washing well the roots, they were extractedsing an electric extractor (Model Ju-209, Guang Dong, China). Thextract was filtered using a fine sieve (0.3 mm) and stored it at20 ◦C for further use. GB in the sugarbeet extract was estimateds described by Grieve and Grattan (1983). The GB concentrationetermined was 50 mmol/kg. The juice was extracted 1 day before

ts foliar application. Sugarbeet extract or pure GB was appliedoliarly at the vegetative stage. Two plants were harvested after0 days of foliar application of sugarbeet extract or pure GB. Afterroperly washing the plant parts, they were weighed for recordingata for shoot and root fresh masses and then dried in an oven at5 ◦C for 1 week for recording dry masses. Data for different yieldelated attributes were recorded at maturity.

.1. Gas exchange characteristics

Instantaneous measurements of gas exchange attributes suchs photosynthetic rate (A), internal CO2 concentration (Ci), tran-piration (E), and stomatal conductance (gs) were performed on aully expanded third leaf (from top) of one plant from each repli-ate using a portable infrared gas analyzer (Model LCA-4; ADC,oddesdon, England). The other adjustments/specifications of the

eaf chamber were as follow: atmospheric pressure (P) 97.9 kPa,eaf surface area 6.25 cm2, leaf chamber temperature (Tch) var-ed from 29.3 to 35.5 ◦C, gas flow rate of leaf chamber volumeV) 296 mL min−1, atmospheric CO2 content (Cref) 369 �mol mol−1,

olar gas flow rate of leaf chamber (U) 400 �mol s−1

turae 125 (2010) 188–195 189

2.2. Determination of glycinebetaine

The method described by Grieve and Grattan (1983) wasemployed to determine GB in leaf tissues. Optical density of theorganic layer was measured at 365 nm using a spectrophotometer(Hitachi-U2001, Tokyo, Japan).

2.3. Determination of proline

Proline in leaf tissues was estimated following the protocol asdescribed by Bates et al. (1973). The absorbance of the chromophorecontaining toluene was read at 520 nm using a spectrophotometer(Hitachi-U2001, Tokyo, Japan). Proline concentration was calcu-lated using the following formula:

�mole proline g−1 fresh weight

= �g proline mL−1 × mL of toluene/115.5g of sample

.

2.4. Mineral nutrients

2.4.1. Na+, K+ and Ca2+

Sodium (Na+), K+ and Ca2+ in the dried ground leaf and roottissues were determined following Allen et al. (1986). The sample sodigested was diluted up to 50 mL in a volumetric flask and filtered.The filtrate was used for the determination of Na+, K+ and Ca2+ usinga flame photometer (Jenway, PFP-7).

2.4.2. Determination of Cl−

Chloride in the plant samples was extracted by heating thematerial in water. Dried ground leaf or root sample (0.1 g) was takenin a test tube and 10 mL of distilled water were added to it, and thenincubated it overnight at 25 ◦C. The tubes were then heated at 80 ◦Cin a digestion block until the volume in the test tubes remainedhalf of the original volume. After cooling, distilled water was addedto each test tube to maintain the volume up to 10 mL again andCl− concentration in the leaf and root extracts determined using achloride analyzer (Model 926, Sherwood, Cambridge, UK).

2.5. Statistical treatment of the data

Analysis of variance of the data for each parameter was com-puted using the statistical software COSTAT version 6.303 (CohortSoftware, Monterey, CA). Least significance difference (LSD) wascalculated following Steel and Torrie (1980) to appraise the signif-icant difference among the mean values within each attribute.

3. Results

Salt stress applied through the root medium (100 mM of NaCl)considerably (P ≤ 0.001) reduced the shoot and root fresh and dryweights of both eggplant cultivars, Bemisal and Dilnasheen. Undersaline regime, cv. Dilnasheen was significantly higher in shoot freshand dry masses, while cv. Bemisal was better in root fresh anddry weights under both control and saline conditions. Of both GBsources, sugarbeet extract was very effective in promoting growthof both eggplant cultivars under salt stress (Table 1 and Fig. 1).

Salt stress markedly suppressed the shoot and root lengths ofboth eggplant cultivars. Cultivar Bemisal was relatively better in

these attributes than cv. Dilnasheen. Both GB sources (natural andpure) had a significant effect in improving shoot and root lengths inboth cultivars. Shoot length was higher at sugarbeet extract whileroot length at 50 mM of pure GB under saline conditions (Table 1and Fig. 1).

190 W. Abbas et al. / Scientia Horticulturae 125 (2010) 188–195

Table 1Mean squares from analyses of variance (ANOVA) of the data for various physio-biochemical attributes of two eggplant (Solanum melongena L.) cultivars differing in salinitytolerance when glycinebetaine obtained from different sources were exogenously applied as foliar spray to salt stressed or non-stressed plants.

Source of variation df Shoot f.wt. Shoot d.wt. Root f.wt. Root d.wt. Shoot length Root length A E gs Ci

Cultivars (Cvs) 1 12.474** 0.206*** 1.354*** 0.015*** 124.0*** 40.425*** 46.68** 1.457*** 5819.0** 17423.1***

Salt stress (S) 1 261.6*** 3.00*** 0.788*** 0.006*** 804.8*** 343.2*** 83.16*** 5.296*** 23034.4*** 17119.6***

Sources of GB (SGB) 2 14.06*** 0.127*** 0.176*** 0.003*** 51.98*** 9.715* 69.91*** 0.113ns 2061.6ns 5104.5***

Cvs × S 1 35.02*** 0.287*** 0.025ns 0.001ns 12.68ns 0.47ns 6.177ns 0.017ns 97.76ns 1185.0nsCvs × SGB 2 1.263ns 0.026ns 0.053* 0.0011* 3.878ns 0.166ns 2.329ns 0.025ns 91.19ns 108.8nsS × SGB 2 11.495*** 0.078*** 0.023ns 0.002ns 9.522ns 19.53*** 6.133ns 0.009ns 416.9ns 1117.4nsCvs × S × SGB 2 1.305ns 0.009ns 0.103** 0.002** 0.129ns 0.661ns 2.542ns 0.016ns 101.5ns 476.7nsError 36 0.987 0.009 0.013 0.0002 4.049 1.908 5.311 0.041 693.5 448.8

Ci/Ca ratio WUE Leaf Na+ Root Na+ Leaf K+ Root K+ Leaf Ca2+ Root Ca2+ Leaf Cl− Root Cl−

Cultivars (Cvs) 1 0.141*** 6.24ns 71.91* 21.66ns 310.1* 18.43ns 9.630** 1.783* 1463.02** 72.52**

Salt stress (S) 1 0.138*** 15.09ns 1019.8*** 167.8*** 3072*** 1510.3*** 145.3*** 28.91*** 20625.5*** 1170.2***

Sources of GB (SGB) 2 0.041*** 22.45ns 22.38ns 0.618ns 97.33ns 61.04ns 12.70*** 0.222ns 340.8ns 4.880nsCvs × S 1 0.009ns 0.258ns 11.262ns 1.595ns 25.521ns 2.876ns 0.521ns 0.012ns 234.1ns 8.333nsCvs × SGB 2 0.009ns 2.147ns 0.227ns 1.488ns 7.771ns 0.876ns 0.083ns 0.0403ns 14.08ns 0.161nsS × SGB 2 0.004ns 0.469ns 20.81ns 2.759ns 122.1ns 13.23ns 5.021** 0.181ns 281.3ns 4.265nsCvs × S × SGB 2 0.004ns 3.735ns 1.41ns 0.493ns 1.083ns 17.18ns 0.474ns 0.238ns 60.02ns 1.943nsError 36 0.0036 26.349 11.02 5.473 51.99 29.90 0.919 0.352 135.8 8.739

Fruit weight No. of fruits Leaf K+/Na+ ratio Root K+/Na+ ratio Free proline GlycinebetaineCultivars (Cvs) 1 90839.3*** 46.02*** 17.32* 2.307ns 3.496ns 28.675**

Salt stress (S) 1 33230.6*** 93.52*** 184.06*** 41.42*** 2046.4*** 96.475***

Sources of GB (SGB) 2 926.04** 40.395*** 5.624ns 0.668ns 3.125ns 105.26***

Cvs × S 1 6261.1*** 1.687ns 1.448ns 0.005ns 0.0634ns 25.099**

Cvs × SGB 2 106.6ns 1.395ns 1.082ns 0.125ns 0.022ns 0.886nsS × SGB 2 13.15ns 1.521ns 0.453ns 0.358ns 1.454ns 2.457nsCvs × S × SGB 2 27.532ns 0.187ns 0.757ns 0.790ns 0.282ns 0.762nsError 36 121.8 0.826 2.432 0.848 1.639 2.288

ns, non-significant; photosynthetic rate (A), transpiration rate (E), stomatal conductance (gs), sub-stomatal CO2 concentration (Ci), water use efficiency (WUE).* Significant at 0.05.

** Significant at 0.01.*** Significant at 0.001.

Fig. 1. Fresh weights, dry weights, and lengths of shoots and roots of two eggplant (Solanum melongena L.) cultivars when 50 mM of pure glycinebetaine or sugarbeet extractwere exogenously applied as foliar spray to salt-stressed and non-stressed plants (n = 4).

W. Abbas et al. / Scientia Horticulturae 125 (2010) 188–195 191

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ig. 2. Various gas exchange characteristics of two eggplant (Solanum melongena Lpplied as foliar spray to salt-stressed and non-stressed plants (n = 4).

Salt stress suppressed the A, E, gs, Ci, and Ci/Ca ratio, while itad non-significant effect on water use efficiency of both eggplantultivars. Of both cultivars, Bemisal was considerably higher thanv. Dilnasheen in all gas exchange attributes, particularly underaline conditions. Of both GB sources, effect of sugarbeet extractas better on A, E and gs than that of pure GB (Fig. 2). However, both

i and Ci/Ca ratio increased on application of synthetic GB (Table 1nd Fig. 2).

Sodium (Na+) accumulation in the leaves and roots wasnhanced in both eggplant cultivars when the plants were exposedo root applied 100 mM NaCl. Both cultivars differed significantlynd cv. Dilnasheen was higher in leaf and root Na+ accumulationhan the other cultivar under saline or non-saline treatments. How-ver, GB (natural or synthetic) did not affect leaf and root Na+

ccumulation of both cultivars (Table 1 and Fig. 3).Potassium (K+) concentration in the leaves and roots of both

ggplant cultivars decreased significantly due to salt stress. Cultivaremisal accumulated higher amount of K+ in the leaves than that

n cv. Dilnasheen under normal or saline conditions, while the K+

ccumulation in the roots was similar in both eggplant cultivars.oth sources of GB (pure or synthetic) did not show effectiveness

n ameliorating the salt-induced adverse effects on leaf and root K+

Table 1 and Fig. 3).Accumulation of Cl− in the leaves and roots of both eggplant

ultivars was considerably enhanced with the imposition of salt in

he rooting medium and considerable difference between cultivarsas observed. Cultivar Dilnasheen accumulated more Cl− in leaves

nd roots as compared to cv. Bemisal. Differential influence of bothB sources was observed on leaf Cl− concentration, and sugarbeetxtract enhanced leaf Cl− accumulation more than that by pure GB.

ivars when 50 mM of pure glycinebetaine or sugarbeet extract were exogenously

However, leaf and root Cl− contents varied inconsistently underboth GB sources (Table 1 and Fig. 3).

Leaf and root Ca2+ was markedly decreased in both eggplant cul-tivars due to salt stress. Both cultivars differed significantly in thisattribute and cultivar Bemisal had higher leaf and root Ca2+ thanthat in cv. Dilnasheen under saline or non-saline treatments. Foliarapplied both GB sources significantly increased leaf Ca2+ and foliarapplied pure GB improved leaf Ca2+ greatly than did the sugarbeetextract. In contrast, root Ca2+ concentration remained unaffecteddue to foliar-applied GB (Table 1 and Fig. 4).

Leaf and root K+/Na+ ratios were significantly lower in salinizedplants of both eggplant cultivars than those in non-salinized plants.Differences between both cultivars were prominent under normalor saline conditions. Cultivar Bemisal was superior to cv. Dilnasheenin leaf K+/Na+ ratios under saline and non-saline conditions. Foliarapplied both GB sources showed consistent results for leaf and rootK+/Na+ ratios (Table 1 and Fig. 4).

Fruit weight and number of fruits per plant were markedlydeclined in both eggplant cultivars subjected to NaCl stress. Bothcultivars differed significantly under saline and normal conditions.Cultivar Bemisal had more fruit weight and number of fruits as com-pared to those of cv. Dilnasheen. Foliar application of GB obtainedfrom both sources had a prominent effect on fruit weight and num-ber of fruits per plant. Sugarbeet extract showed better resultsunder salt stress on these attributes (Table 1 and Fig. 5).

Glycinebetaine (GB) accumulation in the leaves of both eggplantcultivars was considerably enhanced due to NaCl stress. Culti-vars varied in GB accumulation under both saline and non-salineregimes. Glycinebetaine accumulation in cv. Dilnasheen was higherthan that in cv. Bemisal under salt stress. The difference between

192 W. Abbas et al. / Scientia Horticulturae 125 (2010) 188–195

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ig. 3. Leaf and root Na+, K+ and Cl− of two eggplant (Solanum melongena L.) cultivaoliar spray to salt-stressed and non-stressed plants (n = 4).

oth GB sources was significant, and at sugarbeet extract, a maxi-um accumulation of GB was observed in both eggplant cultivars

Table 1 and Fig. 5).Proline concentration in the leaves of both eggplant cultivars

ncreased markedly with salt treatment, however, both eggplantultivars were similar in proline accumulation. A non-significantffect of both GB sources was observed on proline accumulation inoth eggplant cultivars (Table 1 and Fig. 5).

. Discussion

In the present study, a marked decline in growth and yield ofoth eggplant cultivars due to salt stress was observed. These find-

ngs are parallel to what has been earlier reported for eggplantHamdy et al., 2002; Akinci et al., 2004). However, exogenouslypplied both GB sources had a substantial effect in improvingggplant growth under salt stress. Of both GB sources, sugarbeetxtract was found to be more effective than that of pure GB. Shootnd root fresh weights, and root dry weights of eggplant were con-iderably improved with foliar applied sugarbeet extract. Thesendings regarding the influence of glycinebetaine are parallel toome previous studies in which it was shown that exogenouslycinebetaine counteracts growth inhibition induced by salt stressn various crop plants, e.g., tomato (Mäkela et al., 1998; Chen etl., 2009), cotton (Naidu, 1998), rice (Rahman et al., 2002), maize

Nawaz and Ashraf, 2007, 2009), and wheat (Raza et al., 2007;

ahmood et al., 2009).In the present study, salt-induced adverse effects on fruit yield

fruit fresh weight and number of fruits) were also mitigated byhe exogenous application of GB from both sources. However, sug-

en 50 mM of pure glycinebetaine or sugarbeet extract were exogenously applied as

arbeet extract was better in enhancing these yield attributes ofeggplant than pure GB. These findings are supported by Mäkelaet al. (1998) who reported that tomato yield was increased upto 39% when GB obtained from sugarbeet was applied as a foliarspray to salt stressed tomato plants. Since eggplant is naturally a GBnon-accumulator, its improved growth and yield is expected withexogenous application of GB and in the present study, up to 37.4%improvement in eggplant yield was observed under salt stress onsugarbeet extract applied as a foliar spray.

A considerable reduction in photosynthetic rate in both egg-plant cultivars was examined under salt stress in the present study.However, foliar applied GB or sugarbeet extract ameliorated thesalt-induced inhibitory effect on photosynthetic rate of eggplant.In addition, augmentation in photosynthetic capacity due to foliarapplication of GB or sugarbeet extract was more in cv. Bemisal thanthat in cv. Dilnasheen. It is also important to note that in the presentstudy, shoot biomass and fruit yield of eggplant are positively linkedwith A, which indicates that exogenous GB enhanced growth andyield by improving photosynthesis. Similar findings were previ-ously reported in different crops, e.g., tomato (Mäkela et al., 1998),and wheat (Raza et al., 2006; Mahmood et al., 2009).

Internal CO2 level (Ci) and Ci/Ca ratio showed a positive rela-tionship with foliar applied pure GB or sugarbeet extract, whichsuggests that alterations in A due to application of GB or sugarbeetextract were associated with changes in stomatal regulation. Earlier

foliar-applied GB was found to be responsible for stomatal regu-lation in different plant species by means of osmotic adjustment(Mäkela et al., 1998; Raza et al., 2006; Nawaz and Ashraf, 2007,2009). As GB is known to increase cell turgidity through osmoticadjustment (Genard et al., 1991), it is suggested that GB might

W. Abbas et al. / Scientia Horticulturae 125 (2010) 188–195 193

Fig. 4. Leaf and root Ca2+ concentration and leaf and root K+/Na+ ratios of two eggplant (Solanum melongena L.) cultivars when 50 mM of pure glycinebetaine or sugarbeetextract were exogenously applied as foliar spray to salt-stressed and non-stressed plants (n = 4).

Fig. 5. Fruit weight and number of fruits, glycinebetaine and proline contents of two eggplant (Solanum melongena L.) cultivars when 50 mM of pure glycinebetaine orsugarbeet extract were exogenously applied as foliar spray to salt-stressed and non-stressed plants (n = 4).

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ave efficiently increased osmotic adjustment in eggplant plantsccompanied by an increased turgor pressure of the guard cells.

Plants may accumulate compatible solutes such as glycinebe-aine and proline under salt stress, but their relative contributiono stress tolerance varies among species or even among cultivarsf a same species (Mäkela et al., 1999; Ashraf and Foolad, 2007).ndogenous leaf glycinebetaine level was increased in both salt-reated and non-treated plants of both eggplant cultivars withncrease in the concentration of exogenously applied GB. Raza etl. (2007) have shown a similar endogenous GB accumulation inalt-treated wheat plants supplied with exogenous GB. Leaf prolineoncentration also increased in the salt-treated plants of both egg-lant cultivars, but it was not altered by foliar applied GB obtainedrom both sources. Likewise, Mäkela et al. (1998) also reported thatxogenously applied GB did not alter the proline content in tomatond Hassine et al. (2008) in Atriplex halimus grown under salineonditions.

In this investigation, accumulation of Na+ and Cl− in the leavesnd roots of both eggplant cultivars was increased significantlyith salt treatment, while that of K+ and Ca2+ decreased. It is clear

rom these results that like some other crop species the eggplantould not control the uptake of Na+ under salt stress (Hasegawa etl., 1986; Akinci et al., 2004). Cultivar Bemisal accumulated lowermount of Na+ and Cl− and higher of K+ and Ca2+ as well as K+/Na+

atio as compared to those in cv. Dilnasheen. The K+/Na+ ratio isonsidered as a potential selection criterion for evaluating salin-ty tolerance of different crop species (Ashraf, 2004; Akram et al.,009). However, application of GB checked the accumulation ofa+ and Cl− while enhanced that of K+ and Ca2+ in the leaves. Leaf+/Na+ ratio in both eggplant cultivars was also increased with GBpplication under saline conditions. These results can be explainedn the light of some previous reports in which it has been estab-ished that exogenous GB application reduces the accumulation ofa+ and increases that of K+ in the shoots of most plant species

Mäkela et al., 1999; Rahman et al., 2002; Raza et al., 2007; Zhout al., 2007). Gadallah (1999) reported that exogenously appliedB reduced Na+ accumulation and sustained K+ level in the leaves,robably via reduction in stomatal conductance and transpirationhich ultimately checked ion transport.

Overall, foliar applied GB (pure GB and sugarbeet) causedmprovement in growth and yield of both eggplant cultivars, how-ver, sugarbeet extract was more effective than pure GB. Therowth improvement due to GB or sugarbeet extract was foundo be related to improved photosynthetic rate and stomatal con-uctance, high accumulation of K+, Ca2+ and GB, maintenance ofigh K+/Na+ ratio, and low accumulation of Na+ and Cl− in the

eaves. Since the natural source of GB, i.e., sugarbeet extract, was asffective as pure GB in improving growth and some key physiolog-cal processes in eggplant under salt stress, it can be an alternativeheaper source of natural GB. So, it can be used as an ameliora-ive agent for protecting plants against the hazardous effects of salttress.

eferences

kinci, I.E., Akinci, S., Yilmaz, K., Dikici, H., 2004. Response of eggplant varieties(Solanum melongena) to salinity in germination and seedling stages. NZ J. Crop.Hort. Sci. 32, 193–200.

kram, M.S., Ashraf, M., Akram, N.A., 2009. Effectiveness of potassium sulfate in mit-igating salt-induced adverse effects on different physio-biochemical attributesin sunflower (Helianthus annuus L.). Flora 204, 471–483.

llen, S.K., Dobrenz, A.K., Schonhorst, M.H., Stoner, J.E., 1986. Heritability of NaCltolerance in germinating alfalfa seeds. Agron. J. 77, 90–96.

shraf, M., 2004. Some important physiological selection criteria for salt tolerancein plants. Flora 199, 361–376.

shraf, M., Foolad, M.R., 2007. Roles of glycinebetaine and proline in improving plantabiotic stress resistance. Environ. Exp. Bot. 59, 206–216.

shraf, M., Athar, H.R., Harris, P.J.C., Kwon, T.R., 2008. Some prospective strategiesfor improving crop salt tolerance. Adv. Agron. 97, 45–110.

turae 125 (2010) 188–195

Bates, L.S., Waldren, R.P., Teare, I.D., 1973. Rapid determination of free proline forwater stress studies. Plant Sci. 39, 205–207.

Chartzoulakis, K.S., Loupassaki, M.H., 1997. Effects of NaCl salinity on germination,growth, gas exchange and yield of greenhouse eggplant. Agric. Water Manage.32 (3), 215–225.

Chen, S., Gollop, N., Heuer, B., 2009. Proteomic analysis of salt-stressed tomato(Solanum lycposersicum) seedlings: effect of genotype and exogenous applica-tion of glycinebetaine. J. Exp. Bot. 60, 2005–2019.

Craig, S.A., 2004. Betaine in human nutrition. Am. J. Clin. Nutr. 80, 539–549.Gadallah, M.A.A., 1999. Effects of proline and glycinebetaine on Vicia faba responses

to salt stress. Biol. Plant. 42, 249–257.Genard, H., Saos, J.L., Hillad, J., Tremolieres, A., Boucaud, J., 1991. Effect of salin-

ity on lipid composition, glycinebetaine content and photosynthetic activity inchloroplasts of Suaeda maitima. Plant Physiol. Biochem. 29, 421–427.

Grieve, C.M., Grattan, S.R., 1983. Rapid assay for determination of water solublequaternary ammonium compounds. Plant Soil 70 (2), 303–307.

Hamdy, A., Chouaib, W., Pacucci, G., 2002. Eggplant production in soilless cultureunder saline irrigation practices and soil conditioner application. Acta Hort. 633,26–27.

Hasegawa, P.M., Bressan, R.A., Handa, A.K., 1986. Cellular mechanisms of salinitytolerance. Hort. Sci. 21, 1317–1324.

Hassine, B.A., Ghanem, M.E., Bouzid, S., Lutts, S., 2008. An inland and a coastal pop-ulation of the Mediterranean xero-halophyte species Atriplex halimus L. differin their ability to accumulate proline and glycinebetaine in response to salinityand water stress. J. Exp. Bot. 59, 1315–1326.

Heuer, B., Meiri, A., Shalhevet, J., 1986. Salt tolerance of eggplant. Plant Soil 95, 9–13.Kalloo, G., Bergh, B.O., 1993. Genetic Improvement of Vegetable Crops. Pergamon

Press, pp. 587–666.Kantharajah, A.S., Golegaonkar, P.G., 2004. Somatic embryogenesis in eggplant. Sci.

Hort. 99, 107–117.Korteniemi, M., 2007. A short description of glycinebetaine (Bluestim®), Docket No.

AMS-TM-07-0118.Liu, Y., Bolen, D.W., 1995. The peptide backbone plays a dominant role in protein

stabilization by naturally occurring osmolytes. Biochemistry 34, 12884–12891.Mack, G., Hoffmann, C.M., Marlander, B., 2007. Nitrogen compounds in organs of two

sugar beet genotypes (Beta vulgaris L.) during the season. Field Crops Res. 102,210–218.

Mahmood, T., Ashraf, M., Shahbaz, M., 2009. Does exogenous application of glycine-betaine as a pre-sowing seed treatment improve growth and regulate some keyphysiological attributes in wheat plants grown under water deficit conditions?Pak. J. Bot. 41 (3), 1291–1302.

Makela, P., 2004. Agro-industrial uses of glycinebetaine. Sugar Tech. 6 (4), 207–212.Mäkela, P., Jokinen, K., Kontturi, M., Peltonen-Sainio, P., Pehu, E., Somersalo, S.,

1998. Foliar application of glycinebetaine a novel product from sugarbeet asan approach to increase tomato yield. Ind. Crops Prod. 7, 139–148.

Mäkela, P., Kontturi, M., Pehu, E., Somersalo, S., 1999. Photosynthetic response ofdrought and salt stressed tomato and turnip rape plants to foliar applied glycine-betaine. Physiol. Plant. 105, 45–50.

McDonnell, E., Wyn Jones, R.G., 1988. Glycinebetaine biosynthesis and accumulationin unstressed and salt-stressed wheat. J. Exp. Bot. 39 (4), 421–430.

Mukerji, K.G., 2004. Fruit and Vegetable Diseases. Kluwer Academic Publishers,Hingham, MA, USA, p. 145.

Naidu, B.P., 1998. Simultaneous estimation of sugars, polyols, proline analoguesand betaines accumulating in stressed plants by high performance liquidchromatography-ultra violet detection. Aust. J. Plant Physiol. 25, 793–800.

Nawaz, K., Ashraf, M., 2007. Improvement in salt tolerance of maize by exogenousapplication of glycinebetaine: growth and water relations. Pak. J. Bot. 39 (5),1647–1653.

Nawaz, K., Ashraf, M., 2009. Exogenous application of glycinebetaine modulatesactivities of antioxidants in maize plants subjected to salt stress. J. Agron. CropSci. 196 (1), 28–37.

Noreen, Z., Ashraf, M., 2009a. Assessment of variation in antioxidative defense sys-tem in salt treated pea (Pisum sativum L.) cultivars and its putative use as salinitytolerance markers. J. Plant Physiol. 166, 1764–1774.

Noreen, Z., Ashraf, M., 2009b. Changes in antioxidant enzymes and some keymetabolites in some genetically diverse cultivars of radish (Raphanus sativusL.). Environ. Exp. Bot. 67, 395–402.

Park, E.J., Jeknic, Z., Pino, M.T., Murata, N., Chen, T.H., 2007. Glycinebetaine accumula-tion is more effective in chloroplasts than in the cytosol for protecting transgenictomato plants against abiotic stress. Plant Cell Environ. 30 (8), 994–1005.

Rahman, M.S., Miyake, H., Takeoka, Y., 2002. Effects of exogenous glycinebetaine ongrowth and ultrastructure of salt-stressed rice seedlings (Oryza sativa L.). PlantProd. Sci. 5, 33–44.

Rathinasabapathi, B., Burnet, M., Russell, B.L., Gage, D.A., Liao, P.C., Nye, G.J., Scott,P., Golbeck, J.H., Hanson, A.D., 1997. Choline monooxygenase, an unusual iron-sulfur enzyme catalyzing the first step of glycine betaine synthesis in plants:prosthetic group characterization and cDNA cloning. Proc. Natl. Acad. Sci. U.S.A.94, 3454–3458.

Raza, S.H., Athar, H.R., Ashraf, M., 2006. Influence of exogenously applied glycinebe-taine on the photosynthetic capacity of two differently adapted wheat cultivars

under salt stress. Pak. J. Bot. 38, 341–351.

Raza, S.H., Athar, H.R., Ashraf, M., Hameed, A., 2007. Glycinebetaine-induced mod-ulation of antioxidant enzymes activities and ion accumulation in two wheatcultivars differing in salt tolerance. Environ. Exp. Bot. 60, 368–376.

Sakamoto, A., Murata, N., 2002. The role of glycinebetaine in the protection of plantsfrom stress: clue from transgenic plants. Plant Cell Environ. 25, 63–71.

rticul

S

S

W

W

Zhou, S.F., Chen, X.Y., Xue, X.N., Zhang, X.G., Li, Y.X., 2007. Physiological and growth

W. Abbas et al. / Scientia Ho

avvas, D., Lenz, F., 1996. Influence of NaCl concentration in the nutrient solution onmineral composition of eggplants grown in sand culture. Angewandte Botanik70, 124–127.

teel, R.G.D., Torrie, J.H., 1980. Principles and Procedures of Statistics. McGraw HillBook Co., Inc., New York.

eigel, P., Weretilnyk, E.A., Hanson, A.D., 1986. Betaine aldehyde oxidation byspinach chloroplasts. Plant Physiol. 82, 753–759.

ood, K.V., Stringham, K.J., Smith, D.L., Volenec, J.J., Hendershot, K.L., Jackson, K.A.,Rich, P.J., Yang, W.J., Rhodes, D., 1991. Betaines of alfalfa. Characterization by

turae 125 (2010) 188–195 195

fast atom bombardment and desorption chemical ionization mass spectrometry.Plant Physiol. 96, 892–897.

responses of tomato progenies harboring the betaine-aldehyde dehydrogenasegene to salt stress. J. Integ. Plant Biol. 49 (5), 628–637.

Zwart, F.J., Slow, S., Payne, R.J., Lever, M., George, P.M., Gerrard, J.A., Chambers,S.T., 2003. Glycinebetaine and glycinebetaine analogues in common foods. FoodChem. 83, 197–204.