Printer Friendly

Comparative analysis of phytohormones and oxidative damage in flag leaves of six contrasting wheat genotypes in response to drought stress.

Introduction

Drought is one of the most important abiotic factors limiting plant growth in arid and semiarid regions [21], and it is mainly caused by high evaporative demand and low water availability [38]. Plants often suffer from drought stress, and the severity of the resulting damage varies depending on the intensity and duration of the stress. Drought stress could lead to the disruption of cellular membranes, making them more permeable to ions by increased solubilization and peroxidation of membrane lipids under stress conditions and thus impairs both membrane structure and function [45].

Wheat (Triticum aestivum L.) is the staple food for more than 35% of the people in the world and is grown on over 95% of the wheat growing area. Wheat which often experiences water-limited conditions, is an attractive study system because of the natural genetic variation in traits related to drought tolerance [24]. During grain development of wheat, appropriate soil water status is of key importance for accumulation assimilates in grains and thus formation of grain yield and quality [2].

Plants respond to drought and adapt to drought stress through various biochemical changes [28], including changes of the endogenous hormone levels, especially that of abscisic acid (ABA). Plants exposed to drought stress can recruit ABA as an endogenous, signal to initiate adaptive responses [49,58]. However, the variation of IAA and GA contents under drought stress are contradictory. It was reported that drought resulted in a decrease of IAA content in the leaves of wheat [52]. However, other reports have shown that the adaptation to drought was accompanied with an increase in the IAA content [44,40].

Lur and Setter [25] observed that indole-3-acetic acid (IAA) concentrations increased in the endosperm of maize (Zea mays) kernels at about 10 d after pollination. Kato and et al, [18] reported that ABA content in large-size grains was higher than that in small-size grains during rice grain filling. Wang and et al, [50] and Yang and et al, [54] suggested that the poor grain filling was associated with low IAA and ABA contents in rice grains. Improving grain filling is important in cases where slow grain filling is a problem, e.g. heavy use of nitrogen fertilizer [53,49,56,23], or adoption of lodging-resistant cultivars of which some stay "green" for too long [59,57,55]. But yet, our knowledge about the variation of IAA and GA contents in different genotypes of crop plants at under water stress is very rare [56,52], particularly when the drought occurs during reproductive growth, affecting production whether it is for subsistence or economic gain [20].

Besides these, researchers have linked various physiological responses of wheat plants to drought with their tolerance mechanisms such as membrane stability and oxidative damage to plant cells and antioxidant protection [24,16,43]. However, reports regarding variations in these physiological parameters on genotypic basis at reproductive stages such as post anthesis are very rare. Thus, we undertook an experiment to test the six prevalent wheat genotypes under well-watered and drought stress at 7, 17 and 23 days post anthesis (DPA). A special emphasis was placed on plant hormones (ABA, GA3 and IAA), antioxidant enzymes (GR and APX), and hydrogen peroxide ([H.sub.2][O.sub.2]) and total glutathione contents (GSH). Final grain yield and some yield components such as 1000 kernel weight, number of kernels per spike and maturity duration were also recorded.

Materials and Methods

Plant material and drought stress induction:

Wheat (Triticum aestivum L.) cvs Azar-2 and Sardari (tolerant to drought stress), DH-2049, HN7 (moderately tolerant to drought stress), SARA, TEVEE (susceptible to drought stress) were grown in the field of Agricultural Dryland Research Station, Maragheh, Iran (37[degrees] 25' N, 46[degrees] 40'E, 1619 m.s.l.). The seeds were sown on 22 November 2008, in 5 rows with 20 cm row spacing and interplant space of 10 cm adjusting seeding rate of 200 seeds [m.sup.-2]. Soil had an electrical conductivity (EC) 1.4 [dSm.sup.-1], pH 7.5 and sodium adsorption ratio (SAR) of 1.32. Fertilizer was applied at the rate of 110:65:60 kg [ha.sup.-1] N:P:K as split dose, first at 20 days after sowing (DAS) at the rate of 60:65:60 kg [ha.sup.-1] N:P:K and second at 85 DAS at the rate of 50:0:0 kg [ha.sup.-1] N:P:K.

Plants were watered as and when required to keep them fully turgid. The water stress treatment was applied at 7, 17 and 23 days after anthesis (DAA) for a uniform period of 18 days at each treatment. Samples for various assays were taken from flag leaves between 10:30 and 11:30 h at the end of each treatment period. Anthesis in each variety was considered to have occurred when approximately 50% of main shoot ears showed anther dehiscence [43]. However the duration to anthesis was shortened by 4-5 days due to drought stress in all six genotypes. Total rainfall received by wheat plants from sowing to physiological maturity was 2.2 cm. Rainfall was very low between anthesis and post-anthesis periods.

Hydrogen peroxide content and membrane integrity:

Hydrogen peroxide was assayed with titanium reagent [46]. One gram of titanium dioxide and 10 g of potassium sulphate were mixed and digested with 150 ml of concentrated sulphuric acid for 2 h on a hot plate. The digested mixture was cooled and diluted to 1.5 l with distilled water and used as the titanium reagent. Sample preparation and [H.sub.2][O.sub.2] estimation were determined as described by Mukherjee and Choudhuri [30]. Membrane integrity was determined by relative electrolyte leakage (EL) of 2 cm leaf segments floating on distilled water for 24 hat 4[degrees]C (using a conductivity meter), and expressed in percentage of the total leaf electrolyte content obtained after boiling the segments [36].

Total glutathione content:

The glutathione (GSH) content was measured as described by Griffith and Meister [15]. Fresh leaves were homogenized in 2 mL of 2 % metaphosphoric acid and centrifuged at 17,000 x g for 10 min. The addition of 0.6 mL 10% sodium citrate neutralized the supernatant. One milliliter of assay mixture was prepared by adding 100 [micro]L extract, 100 [micro]L distilled water, 100 [micro]L of 6 mM 5,5-dithio-bis-(2-nitrobenzoic acid) (DTNB) and 700 [micro]L of 0.3 mM NADPH. The mixture was stabilized at 25[degrees]C for 3-4 min. Then, 10 [micro]L of glutathione reductase was added, and the absorbance was measured at 412 nm in a spectrophotometer; the GSH content is expressed in [micro]g [g.sup.-1] dry weight (DW).

Antioxidant enzymes assay:

The GR activity was determined spectrophotometrically at 30[degrees]C as described by Barata and et al., [4] in a reaction mixture consisting of 3 ml 100 mM potassium phosphate buffer (pH 7.5) containing 1 mM 5,5"-dithiobis(2-nitrobenzoic acid), 1 mM oxidized glutathione and 0.1 mM NADPH. The reaction was initiated by the addition of 50 [micro]l of plant extract. The rate of reduction of oxidized glutathione was followed by monitoring the increase in absorbance at 412 nm over 2 min. The GR activity of the extract was expressed as GR units [min.sup.-1] [mg.sup.-1] protein.

Ascorbate peroxidase (APX) was assayed by recording the decrease in absorbance at 290 nm due to a decrease in ascorbic acid content [31]. Reaction mixture (3 mL) contained 50 mM potassium phosphate buffer (pH 7.8), 0.5 mM ascorbic acid, 0.1 mM EDTA, and 1.5 mM [H.sub.2][O.sub.2] and 0.1 mL enzyme extract. The reaction was started with the addition of [H.sub.2][O.sub.2]. Absorbance was measured at 290 nm for 3 min. The APX activity of the extract was expressed as APX units [min.sup.-1] [mg.sup.-1] protein.

Determination of plant phytohormones:

Five grams of leaf samples were used for ABA, GA3 and IAA extraction, according to the method of Kelen and et al., [19]. Briefly, leaf samples were homogenized in methanol 70% and stirred overnight at 4[degrees]C. After filtration through a Whatman 0.45 [micro]m filter, the extracts were completely evaporated under vacuum and dissolved in water. The solutions were partitioned with diethyl ether three times and then passed through anhydrous sodium sulphate. After evaporation of the non-polar phase, the dry residue was dissolved in 3 mL of methanol and the solution was used directly for injections. Analysis was performed in three replicates for each treatment.

The high performance liquid chromatography (HPLC) analysis was performed on a Waters HPLC system equipped with Empower software, a pump (Waters 600, USA), and a UV-Vis detector (Waters model 2487). A column, [mu]BondapackTM C18, from Waters (Ireland) was used for the separation. The mobile phase was acetonitrile-water containing 30 mM phosphoric acid at pH 4.0, flow rate 0.8 [micro]L [min.sup.-1]. For each extraction, three different injections in HPLC were performed. Each of the standard solutions was detected at wavelengths of 208, 265 and 280 nm for GA3, ABA and IAA, respectively. To quantify the GA3, ABA and IAA contents, known amounts of pure standards (Sigma) were injected into HPLC system and equations, correlating peak area to concentrations of GA3, ABA and IAA, were formulated.

Statistical analysis:

All data were subjected to two analysis of variance (ANOVA) using the GLM procedure in SAS (SAS release 9.1.2, 2004). The assumptions of variance analysis were tested by insuring that the residuals were random, homogenous, with a normal distribution about a mean of zero. The significance of differences among treatment means were compared by Fisher's least-significant difference test (LSD). Values presented in graphs are mean [+ or -] SD. In graphs, bars with different alphabets differ significantly from each other.

Results:

Hydrogen peroxide content ([H.sub.2][O.sub.2]) in the flag leaves of wheat cultivars increased under water stress (Fig. 1). The lowest H2O2 contents were observed in Azar-2 and Sardari, and the highest in SARA and TEVEE at all stages both under well-watered and under drought stress conditions. DH-2049 and HN7 showed intermediate levels at all stages under both well-watered and under drought stress conditions. The electrolyte leakage (EL) also increased markedly under first drought stage and then showed a declining trend after second stage (Fig. 2). The highest EL was observed in SARA and TEVEE and the lowest in Azar-2 and Sardari under well-watered conditions. Similar results were also obtained under drought stress conditions.

GSH content decreased under water stress (Fig. 3). All the genotypes showed higher GSH content at the first drought stage (7 DPA). Amongst the genotypes, the highest GSH content was observed in Azar-2 and Sardari, and the lowest in SARA and TEVEE at all stages in both environments. The GSH also decreased under drought stress and also showed a declining trend with age.

GR activity increased significantly under drought stress conditions at all the stages (Fig. 4). The genotypic response was significant at all stages under both well-waterd and drought stress conditions, so the highest GR activity was observed in tolerant genotypes (Azar-2 and Sardari) and the lowest in susceptible genotypes (SARA and TEVEE) under both well-watered and drought stress conditions. Moderately genotypes (DH-2049 and HN7) also exhibited an intermediate response.

Ascorbate peroxidase (APX) activity increased under drought stress as well as with age (Fig. 5). The lowest APX activity were observed in SARA and TEVEE, and the highest in Azar-2 and Sardari at all stages both under well-watered and under drought conditions. DH-2049 and HN7 showed intermediate levels at all stages under both well-watered and drought stress conditions.

Under drought stress conditions, endogenous ABA contents were sharply increased under drought stress as well as with age (Fig. 6). The lowest ABA contents was observed in SARA and TEVEE, and the highest in Azar-2 and Sardari at all stages both under well-watered and under drought conditions. Two moderately tolerant genotypes showed intermediate ABA contents at all stages under both well-watered and drought stress conditions.

[FIGURE 1 OMITTED]

[FIGURE 2 OMITTED]

[FIGURE 3 OMITTED]

[FIGURE 4 OMITTED]

[FIGURE 5 OMITTED]

[FIGURE 6 OMITTED]

The endogenous IAA content showed an increasing trend with age under well-watered conditions (Fig. 7). Drought stress notably decreased IAA contents. Under drought stress conditions, IAA content increased from 7 DPA and reached a peak at 17 DPA under water stress; however, it dropped at 23 DPA (Fig. 7). The lowest IAA contents was observed in SARA and TEVEE, and the highest in Azar-2 and Sardari at all stages both under well-watered and under drought conditions. Two moderately tolerant genotypes showed intermediate IAA contents at all stages under both environments.

Similar to IAA, GA3 content displayed an increasing trend with age under well-watered conditions (Fig. 8). Under drought stress conditions, the levels of endogenous GA3 changed inconsistently among genotypes and drought stages. The genotypes TEVEE (susceptible), DH-2049 (moderately tolerant) and Sardari (tolerant) showed a declining trend with age under drought stress. But, the genotypes SARA (susceptible) and HN7 (moderately tolerant) showed an increase from 7 DPA to 17 DPA; however, it dropped at 23 DPA. The lowest GA3 contents was observed in SARA and TEVEE, and the highest in Azar-2 and Sardari both under well-watered and under drought conditions.

As shown in Table 1, final grain yield was highest in case of SARA while lowest in DH-2049 in well-watered plants. Under drought stress conditions, HN7 exhibited the highest grain yield, closely followed by Sardari and Azar-2, while SARA and DH-2049 showed the lowest grain yield. Lowest grain yield in all the genotypes were observed at third drought stage (23 DPA), and the highest grain yield in all the cultivars except Sardari were observed under control conditions. The lowest rate of decrease in yield was obtained in tolerant genotypes (0.33 in Sardari), and the highest (0.72 in SARA) was obtained in susceptible genotypes.

[FIGURE 7 OMITTED]

Under drought stress conditions, number of kernels per spike and maturity duration (MD) was decreased under drought stress (Table 1). Maturity duration (MD) was calculated from the onset of anthesis stage to physiological maturity in the studied genotypes.

The lowest number of kernels and MD was observed in Azar-2 and Sardari (tolerant genotypes), and the highest in SARA and TEVEE (susceptible genotypes) under both well-watered and under drought stages. Two moderately tolerant genotypes had intermediate number of kernels at all stages under both well-watered and drought stress conditions. Drought stress at 7 DPA led to higher reduction in number of kernels and MD, followed by drought at 17 and 23 DPA (Table 1).

Similar to the number of kernels per spike and MD, 1000 kernel weight was decreased under drought stress (Table 1). But the lowest 1000 kernel weight was observed in SARA and TEVEE (susceptible genotypes), and the highest in Azar-2 and Sardari (tolerant genotypes) under both well-watered and under drought stages (Table 1).

[FIGURE 8 OMITTED]

Discussion:

The development of more drought-resistant crops is necessary to alleviate future threats to food availability in the world [39]. However, this requires comprehensive studies of the many potential genetic resources and understanding of the adaptive mechanisms and responses to drought stress that allows survival in arid and semiarid environments [43,41].

Physiological and genetic evidence clearly indicates that the reactive oxygen species (ROS) scavenging systems of crop plants are an important component of the stress protective mechanism [33,34,43]. In this study, both the tolerant genotypes had lower H202 content and electrolyte leakage under drought stress than the susceptible genotypes SARA and TEVEE, while DH-2049 and HN7 (moderately tolerant cultivars) exhibited an intermediate response. This may be due to higher membrane stability in tolerant cultivars (Azar-2 and Sardari), than in susceptible ones (SARA and TEVEE) [43].

Hydrogen peroxide is a toxic compound produced as a result of the dismutation of the superoxide radical, and a higher concentration is injurious to the plant cells, resulting in lipid peroxidation and membrane injury [27,24,43].

Tolerant genotypes, which had lower [H.sub.2][O.sub.2] content and electrolyte leakage under drought stress, also showed higher GR and APX activity as compared to susceptible and moderately tolerant genotypes under drought stress as well as well-watered conditions at all the stages. These two antioxidant enzymes are involved in the scavenging of the products of oxidative stress, such as hydrogen peroxide generated in the chloroplast [13,14,29,17,43], and thus help in ameliorating the damaging effects of oxidative stress. Elevated GR activity during stomatal closure in response to drought stress may also serve to ensure the availability of NADP to accept electrons derived from photosynthetic electron transport, thereby directing electrons away from oxygen and minimizing the chances of production of superoxide radicals [10,12,11,43]. In this study tolerant genotypes also showed higher GSH content activity as compared to susceptible and moderately tolerant genotypes. Increased GR and APX activity in drought-tolerant genotypes of maize [37], tomato [48], tobacco [47] and wheat [43] has also been reported. Lesser oxidative damage in the tolerant wheat cultivar during osmotic stress has been attributed to higher AsA and GSH content, and induction of AsA-GSH cycle enzymes [22,43].

A number of studies have described the ABA content in tolerant and susceptible wheat genotypes and the relationship between ABA content and the grain-filling rate [56,49,55]. Here, we found that the maturity duration (MD) of all the genotypes, under either the well-watered or drought stress condition, were closely associated with ABA contents in flag leaves (Fig 6, Table 1). The tolerant genotypes had higher ABA concentrations and shorter MD than the susceptible genotypes. In spite of MD, drought stress led to a reduction in number of kernels per spike in both tolerant and susceptible genotypes, and this increase was also accompanied by an increase in ABA content in these genotypes. These results imply that ABA was responsible for senescence acceleration and grain-filling shortening owing to the lasting water stresses [35,55].

It has also been proposed that ABA has a major role in relation to sugar-signaling pathways and enhances the ability of plant tissues to respond to subsequent sugar signals [42,8]. There are many reports that ABA can enhance the movement of photosynthetic assimilates towards to developing seeds [9,1,5].

The present results showed that endogenous [GA.sub.3] contents under well-watered conditions changed inconsistently at the post anthesis stage, but markedly decreased under drought stress conditions. The present finding suggests that the reduced [GA.sub.3] contents under drought stress may be attributed to the depressed GA synthesis resulting from the accelerating senescence of the organs [52,55]. Amongst the genotypes, tolerant genotypes had higher [GA.sub.3] contents under both well-watered and drought stress conditions. As a result, [GA.sub.3] contents in the flag leaves at post anthesis stage under drought stress conditions were positively related to 1000 kernel weight, suggesting that GA plays an important role in accumulation of assimilates in wheat grains.

It has been reported that IAA level in wheat grains increased at the post anthesis stage, and played an important role in regulation of grain filling [52,5]. The positive effects of IAA on photoassimilate translocation within developing wheat grains have also been reported in other studies [3,6]. These results are consonant with the present study, indicating that IAA may be involved in photosynthate translocation into grains.

Here, we also observed that the 1000 kernel weight of all the genotypes, under either the well-watered or drought stress condition, were closely associated with IAA contents in flag leaves (Fig. 7, Table 1). The tolerant genotypes (Azar-2 and Sardari) had higher IAA contents and higher 1000 kernel weight than the susceptible genotypes that may be due to the higher grain filling rate in tolerant genotypes than that of susceptible ones. Davies [7] stated that auxin also stimulates cell division. It has been reported that IAA can increased the transpiration rate by inducing stomatal opening, with a concomitant increase in transpiration and photosynthesis rate [51,32].

In addition, since the high IAA content of flag leaves can lead to the enhancement of ethylene synthesis [26,49], the higher IAA contents in tolerant genotypes under drought stress at post anthesis stage may be related to the stress induced shortening in grain-filling period and the acceleration of plant senescence.

Generally, our results showed that oxidative stress as a result of drought stress conditions, increases [H.sub.2][O.sub.2] contents and electrolyte leakage, resulting in greater membrane injury. The higher antioxidant enzyme activity in tolerant genotypes was associated with the lower [H.sub.2][O.sub.2] contents and electrolyte leakage. The finding of higher GSH content, and higher GR and APX activity in tolerant genotypes compared with susceptible genotypes, provide better protection from oxidative stress, which otherwise could cause damage to the cell membrane and organelles, protein and DNA structure and inhibit photosynthesis and other enzyme activities. The changes in oxidative damage, grain yield, 1000 kernel weight, kernels per spike and maturity duration under drought were associated with the reduced contents of IAA and GA3 and elevated content of ABA in different wheat genotypes. However, the complex regulatory network of plant hormone signaling in plants subjected to drought stress needs to be explored, and the stress-related genes involved in the network of plant hormone signaling await identification. The changes of endogenous hormones in the flag leaves of wheat plants subjected to drought stress were detailed, which would allow a better understanding of the drought response and improvement strategy for drought tolerance of crop plants.

References

[1.] Ackerson, R.C., 1985. Invertase activity and abscisic acid in relation to carbohydrate status in developing soybean reproductive structures. Crop Science, 25: 615-618.

[2.] Ahmadi, A. and D.A. Baker, 2001. The effect of water stress on the activities of key regulatory enzymes of the sucrose to starch pathway in wheat. Plant Growth Regulation, 35: 81-91.

[3.] Bangerth, F., W. Aufhammer and O. Baum, 1985. IAA level and dry matter accumulation at different positions with a wheat ear. Physiologiae Plantarum, 63: 121-125.

[4.] Barata, R.M., A. Chapparro, S.M. Chabregas, R. Gonzalez, C.A. Labate, R.A. Azevedo, G. Sarath, P.J. Lea and M.C. Silva-Filho, 2000. Targeting of the soybean leghemoglobin to tobacco chloroplasts: Effects on aerobic metabolism in transgenic plants. Plant Science, 155: 193-202.

[5.] Brenner, M.L. and N. Cheikh, 1995. The role of hormones in photosynthate partitioning and seed filling. In: DaviesPJ, ed. Plant hormones, physiology, biochemistry and molecular biology. Dordrecht, the Netherlands: Kluwer Academic Publishers, 649-670.

[6.] Darussalam Cole, M.A. and J.W. Patrick, 1998. Auxin control of photoassimilate transport to and within developing grains of wheat. Australian Journal of Plant Physiology, 25: 69-77.

[7.] Davies, K.J.A., 1987. Protein damage and degradation by oxygen radicals. I. General aspects. Journal of Biological Chemistry, 262: 9895-9901.

[8.] Davies, P.J., 2004. Introduction. In: DaviesPJ, ed. Plant hormones, biosynthesis, signal transduction, action! Dordrecht, the Netherlands: Kluwer Academic Publishers, 1-35.

[9.] Dewdney, S.J. and J.A. McWha, 1979. Abscisic acid and the movement of photosynthetic assimilates towards developing wheat (Triticum aestivum L.) grains. Z Pflanzenphysiol, 92: 186-193.

[10.] Egneus, H., U. Heber and M. Kirk, 1975. Reduction of oxygen by the electron transport chain of chloroplasts during assimilation of carbon dioxide. Biochimica and Biophysica Acta, 408: 252-268.

[11.] Elstner, E.F., 1987. Metabolism of activated oxygen species. In: Davies DD, ed. The Biochemistry of Plants, Biochemistry of Metabolism, Vol. 11, pp. 253 315. Academic Press, San Diego, USA.

[12.] Foster, J.G. and J.L. Hess, 1982. Oxygen effects on maize leaf superoxide dismutase and glutathione reductase. Phytochemistry, 21: 1527-1532.

[13.] Gamble, P.E. and J.J. Burke, 1984. Effect of water stress on the chloroplast antioxidant system. 1. Alterations in glutathione reductase activity. Plant Physiology, 76: 615-621.

[14.] Gillham, D.J. and A.D. Dodge, 1987. Chloroplast superoxide and hydrogen peroxide scavenging systems from pea leaves: seasonal variations. Plant Science, 50: 105-109.

[15.] Griffith, O.W. and A. Meister, 1979. Potent and specific inhibition of glutathione synthesis by buthionine sulfoximine (S-n-butylhomocysteine sulfoximine). Journal of Biological Chemistry, 254: 7558-7560.

[16.] Hameed, A., N. Bibi, J. Javed and N. Iqbal, 2011. Differential changes in antioxidants, proteases, and lipid peroxidation in flag leaves of wheat genotypes under different levels of water deficit conditions. Plant Physiology and Biochemistry, 49: 178-185.

[17.] Jagtap, V. and S. Bhargava, 1995. Variation in the antioxidant metabolism of drought tolerant and drought susceptible varieties of Sorghum bicolor (L) Moench, exposed to high light, low water and high temperature stress. Journal of Plant Physiology, 145: 195-197.

[18.] Kato, T., N. Sakurai and S. Kuraishi, 1993. The changes of endogenous abscisic acid in developing grains of two rice cultivars with different grain size. Japanese Journal of Crop Science, 62: 456-461.

[19.] Kelen, M., E. Cubek Demiralay, S. Sen and G. Ozkan, 2004. Separation of abscisic acid, indole-3-acetic acid, gibberellic acid in 99 R (Vitis berlandieri x Vitis rupestris) and Rose Oil (Rosa damascena Mill.) by Reversed Phase Liquid Chromatography. Turk Journal of Chemistry, 28: 603-610.

[20.] Khanna-Chopra, R. and D.S. Selote, 2007. Acclimation to drought stress generates oxidative stress tolerance in drought-resistant than-susceptible wheat cultivar under field conditions. Environmental and Experimental Botany, 60: 276-283.

[21.] Kramer, P.J. and J.S. Boyer, 1995. Water Relations of Plants and Soils. San Diego: Academic Press.

[22.] Lascano, H.R., G.E. Antonicelli, C.M. Luna, M.N. Melchiorre, L.D. Gomez, R.W. Racca, V.S. Trippi and L.M. Casano, 2001. Antioxidant system response of different wheat cultivars under drought: field and in vitro studies. Australian Journal of Plant Physiology, 28: 1095-1102.

[23.] Ling, Q., H. Zhang, J. Cai and Z. Su, 1993. Population quality and its approaches for the high-yielding of rice. Scientia Agricultura Sinica, 6: 1-11.

[24.] Loggini, B., A. Scartazza, E. Brugnoli and F. Navari-Izzo, 1999. Antioxidant defense system, pigment composition, and photosynthetic efficiency in two wheat cultivars subjected to drought. Plant Physiology, 119: 1091-1099.

[25.] Lur, H.S. and T.L. Setter, 1993. Role of auxin in maize endosperm development: timing of nuclear DNA endoreduplication, zein expression, and cytokinins. Plant Physiology, 103: 273-280.

[26.] Mckeon, T.A. and S.F. Yang, 1988. Biosynthesis and metabolism of ethylene In: Davies P.J. (ed.), Plant Hormones and their Role in Plant Growth and Development. Kluwer Academic Publishers, Dordrecht, pp: 94-112.

[27.] Menconi, M., C.L.M. Sgherri, C. Pinzino and F. Navari-Izzo, 1995. Activated oxygen production and detoxification in wheat plants subjected to a water deficit programme. Journal of Experimental Botany, 46: 1123-1130.

[28.] Monneveux, P. and E. Belhassen, 1996. The diversity of drought adaptation in the wild. Plant Growth Regulation, 20: 85-92.

[29.] Moran, J., F. Becana, I. Iturbe-Ormaetxe, S. Frenhilla, R.V. Klucas and P. Aparicio-Teju, 1994. Drought induces oxidative stress in pea plants. Planta, 194: 346-352.

[30.] Mukherjee, S.P. and M.A. Choudhuri, 1983. Implications of water stress-induced changes in the levels of endogenous ascorbic acid and hydrogen peroxide in Vigna seedlings. Physiologiae Plantarum, 58: 166-170.

[31.] Nakano, Y. and K. Asada, 1981. Hydrogen peroxide is scavenged by ascorbate specific peroxidase in spinach chloroplasts. Plant and Cell Physiology, 22: 867-880.

[32.] Narwadkar, P.R. and K.W. Ansewadekar, 1989. Effect of growth regulator on the success of epicotyl grafting in mango. Acta Horticulture, 231: 175-178.

[33.] Noctor, G. and C.H. Foyer, 1998. Ascorbate and glutathione: Keeping active oxygen under control. Annual Reviews of Plant Physiology and Plant Molecular Biology, 49: 249-279.

[34.] Noctor, G., L. Gomez, H. Vanacker and C.H. Foyer, 2002. Interactions between biosynthesis comportmentation and transport in the control of glutathione homeostasis and signaling. Journal of Experimental Botany, 53: 1283-1304.

[35.] Nooden, L.D., 1988. Abscisic acid, auxin, and other regulators of senescence. In: Nooden L. and Leopold A. (eds), Senescence and Aging in Plants. Academic Press, San Diego, pp: 329-368.

[36.] Nunes, M.E.S. and G.R. Smith, 2003. Electrolyte leakage assay capable of quantifying freezing resistance in rose clover. Crop Science, 43: 1349-1357.

[37.] Pastori, G.M. and V.S. Trippi, 1992. Oxidative stress induces high rate of glutathione reductase synthesis in a drought resistant maize strain. Plant and Cell Physiology, 33: 957-961.

[38.] Patakas, A. and B. Notsakis, 2001. Leaf age effects on solute accumulation in water-stressed grapevines. Journal of Plant Physiology, 158: 63-69.

[39.] Plucknett, D.L., N.J.H. Smith, J.T. Williams and N.M. Anishetty, 1987. Gene Banks and the World's Food. Princeton University Press, New York.

[40.] Pustovoitova, T.N., N.E. Zhdanova and V.N. Zholkevich, 2004. Changes in the levels of IAA and ABA in cucumber leaves under progressive soil drought. Russian Journal of Plant Physiology, 51: 513-517.

[41.] Rampino, P., S. Pataleo, C. Gerardi, G. Mita and C. Perrotta, 2006. Drought stress response in wheat: physiological and molecular analysis of resistant and sensitive genotypes. Plant Cell and Environment, 29: 2143-2152.

[42.] Rook, F., F. Corke, R. Card, G. Munz, C. Smith and M.W. Bevan, 2001. Impaired sucrose-induction mutants reveal the modulation of sugar-induced starch biosynthetic gene expression by abscisic acid signaling. Plant Journal, 26: 421-433.

[43.] Sairam, R.K. and D.C. Saxena, 2000. Oxidative stress and antioxidants in wheat genotypes: possible mechanism of water stress tolerance. Journal of Agronomy and Crop Science, 184: 55-61.

[44.] Sakurai, N., M. Akiyama and S. Kuraishi, 1985. Role of abscisic acid and indoleacetic acid in the stunted growth of water-stressed, etiolated squash hypocotyls. Plant and Cell Physiology, 26: 15-24.

[45.] Saneoka, H., R.E.A. Moghaieb, G.S. Premachandra and K. Fujita, 2004. Nitrogen nutrition and water stress effects on cell membrane stability and leaf water relations in Agrostis palustris Huds. Environmental and Experimental Botany, 52: 131-138.

[46.] Teranishi, Y., A. Tanaka, M. Osumi and S. Fukui, 1974. Catalase activity of hydrocarbon utilizing candida yeast. Agricultural and Biological Chemistry, 38: 1213-1216.

[47.] Van Rensburg, L. and G.H.J. Kruger, 1994. Evaluation of components of oxidative stress metabolism for use in selection of drought tolerant cultivars of Nicotiana tobacum L. Journal of Plant Physiology, 143: 730-736.

[48.] Walker, M.A. and B.D. McKersie, 1993. Role of the ascorbate-glutathione antioxidant system in chilling resistance of tomato. Journal of Plant Physiology, 141: 234-239.

[49.] Wang, C., A. Yang, H. Yin and J. Zhang, 2008. Influence of water stress on endogenous hormone contents and cell damage of maize seedlings. Journal of Integrative Plant Biology, 50: 427-434.

[50.] Wang, Z., J. Yang, Q. Zhu, Z. Zhang, Y. Lang and X. Wang, 1998. Reasons for poor grain filling in intersubspecific hybrid rice. Acta Agronomica Sincia, 24: 782-787.

[51.] Wittenbach, V.A., 1983. Effect of pod removal on leaf photosynthesis and soluble protein composition of field-grown soybeans. Plant Physiology, 73: 121-124.

[52.] Xie, Z.J., D. Jiang, W.X. Cao, T.B. Dai and Q. Jing, 2003. Relationships of endogenous plant hormones to accumulation of grain protein and starch in winter wheat under different post-anthesis soil water statuses. Plant Growth Regulation, 41: 117-127.

[53.] Yang, J., Z. Wang and Q. Zhu, 1996. Effect of nitrogen nutrition on grain yield of rice and its physiological mechanism under different soil moisture. Scientia Agricultura Sinica, 4: 7-14.

[54.] Yang, J., Z. Wang, Q. Zhu, Y. Lang, 1999. Regulation of ABA and GA to rice grain filling. Acta Agronomica Sincia, 25: 341-348.

[55.] Yang, J., J. Zhang, K. Liu, Z. Wang and L. Liu, 2006. Abscisic acid and ethylene interact in wheat grains in response to soil drying during grain filling. New Phytologist, 271: 293-303.

[56.] Yang, J., J. Zhang, Z. Wang, Q. Zhu and W. Wang 2001. Hormonal changes in the grains of rice subjected to water stress during grain filling. Plant Physiology, 127: 315-323.

[57.] Yuan, L.P., 1997. Hybrid rice breeding for super high yield. Hybrid Rice, 12: 1-6.

[58.] Zhu, J.K., 2002. Salt and drought stress signal transduction in plants. Annual Review of Plant Biology, 53: 247-273.

[59.] Zhu, Q., Z. Zhang, J. Yang, X. Cao, Y. Lang and Z. Wang, 1997. Source-sink characteristics related to the yield in inter subspecific hybrid rice. Scientia Agricultura Sinica, 4: 52-59.

(1) Parisa Sharifi, (1) Reza Amirnia, (2) Eslam Majidi, (1) Hashem Hadi, (2) Foad Moradi, (3) Mozafar Roustaei, (3) Jafar Jafarzadeh

(1) Department of Agronomy and plant breeding, Faculty of Agriculture, Urmia University, Urmia, Iran

(2) Department of Molecular Physiology, Agricultural Biotechnology Research Institute of Iran, Karaj, Iran

(3) Dryland Agricultural Research Institute (DARI), P.O. Box 119, Maragheh, Iran

Parisa Sharifi, Reza Amirnia, Eslam Majidi, Hashem Hadi, Foad Moradi, Mozafar Roustaei, Jafar Jafarzadeh; Comparative Analysis of Phytohormones and Oxidative Damage in Flag Leaves of Six Contrasting Wheat Genotypes in Response to Drought Stress

Corresponding Author

Parisa Sharifi, Department of Agronomy and plant breeding, Faculty of Agriculture, Urmia University, Urmia, Iran

Email: Sharifip89@gmail.com
Table 1: Effects of drought stress on final grain yield,
Kernels per spike, 1000 kernel weight and Maturity
duration of different wheat genotypes.

Genotype     Treatments          Grain yield
                              (kg [hec.sup.-1])

SARA          Control         3779[+ or -]101 a
           Drought 7 DPA    2186 [+ or -] 72 lmn
           Drought 17 DPA   1865 [+ or -] 146 op
           Drought 23 DPA     1446[+ or -] 18 q

TEVEE         Control       2519 [+ or -] 67 hij
           Drought 7 DPA      2191[+ or -] 48lm
           Drought 17 DPA   1878 [+ or -] 110 op
           Drought 23 DPA     1517[+ or -] 10 q

DH-2049       Control       2125 [+ or -] 65 lmn
           Drought 7 DPA    2170 [+ or -] 32 lmn
           Drought 17 DPA     1839[+ or -] 93 p
           Drought 23 DPA      1461[+ or -]30q

HN7           Control        3244 [+ or -] 87 bc
           Drought 7 DPA    2821 [+ or -] 61 efg
           Drought 17 DPA   2460 [+ or -] 125 ijk
           Drought 23 DPA   1954 [+ or -] 63 nop

Azar-2        Control        3464 [+ or -] 92 b
           Drought 7 DPA    2713 [+ or -] 66 fgh
           Drought 17 DPA   2827 [+ or -] 133 efg
           Drought 23 DPA   2087 [+ or -] 14 mno

Sardari       Control       2449 [+ or -] 60 hij
           Drought 7 DPA    2739 [+ or -] 121 fgh
           Drought 17 DPA   2388 [+ or -] 73 jkl
           Drought 23 DPA    1897 [+ or -] 73 op

Genotype           Kernels                 1000 kernel
               [spike.sup.-1]              weight (gr)

SARA       29.73 [+ or -] 0.74 ab    28.28 [+ or -] 0.73 hij
            19.29 [+ or -] 0.91 g     20.96 [+ or -] 1.33 n
           22.16 [+ or -] 0.65 ef     24.16 [+ or -] 0.77 lm
           25.19 [+ or -] 0.44 cd     25.88 [+ or -] 0.92 kl

TEVEE       30.34 [+ or -] 0.83 a    28.56 [+ or -] 0.78 ghij
            18.61 [+ or -] 0.45 g     22.11 [+ or -] 0.37 mn
           22.12 [+ or -] 0.91 ef     24.91 [+ or -] 0.58 l
           25.02 [+ or -] 0.55 cd    26.39 [+ or -] 0.58 jkl

DH-2049     27.95 [+ or -] 1.14 b     33.96 [+ or -] 0.81 cd
            16.12 [+ or -] 2.37 h     25.01 [+ or -] 1.02 l
           22.11 [+ or -] 0.21 ef    27.72 [+ or -] 0.20 hijk
           24.06 [+ or -] 0.35 cde   29.90 [+ or -] 0.83 fgh

HN7         25.70 [+ or -] 0.28 c     33.19 [+ or -] 0.94 de
            18.84 [+ or -] 0.33 g     24.51 [+ or -] 0.91 l
           20.75 [+ or -] 0.27 fg    27.45 [+ or -] 0.22 ijk
           23.31 [+ or -] 0.79 de    29.62 [+ or -] 0.69 fghi

Azar-2     25.02 [+ or -] 0.08 cd     42.60 [+ or -] 1.21 a
            15.37 [+ or -] 0.97 h     31.29 [+ or -] 0.69 ef
            18.92 [+ or -] 0.28 g     33.86 [+ or -] 0.56 d
           22.29 [+ or -] 0.37 ef     37.21 [+ or -] 0.80 b

Sardari    23.82 [+ or -] 0.36 cde    41.67 [+ or -] 1.21 a
            16.29 [+ or -] 0.95 h     30.84 [+ or -] 0.76 fg
            19.32 [+ or -] 0.21 g     33.35 [+ or -] 0.55 de
           22.07 [+ or -] 0.24 ef     36.25 [+ or -] 0.81 bc

Genotype           Maturity
                duration (day)

SARA        38.92 [+ or -] 1.08 a
           31.85 [+ or -] 0.57 efgh
           34.26 [+ or -] 0.55 cde
            36.24 [+ or -] 0.35 bc

TEVEE       38.72 [+ or -] 0.51 ab
            28.26 [+ or -] 2.34 ij
           36.39 [+ or -] 0.45 abc
             37.54 [+ or -] 10 ab

DH-2049     36.28 [+ or -] 1.64 bc
            27.36 [+ or -] 1.52 jk
           32.06 [+ or -] 0.27 efgh
           33.56 [+ or -] 0.13 defg

HN7         38.23 [+ or -] 0.15 ab
            28.37 [+ or -] 0.60 ij
            31.07 [+ or -] 0.75 gh
           33.52 [+ or -] 0.27 defg

Azar-2     33.95 [+ or -] 0.80 cdef
            26.03 [+ or -] 1.00 jk
            30.06 [+ or -] 0.95 hi
           31.56 [+ or -] 0.57 fgh

Sardari     34.80 [+ or -] 0.31 cd
            25.39 [+ or -] 0.34 k
            30.09 [+ or -] 1.59 hi
           31.66 [+ or -] 0.87 efgh

Values are means [+ or -] S.E. (n = 8) and differences
between means were compared by Fishers least significance
test. Different letters indicate significant differences
at P < 0.05.
COPYRIGHT 2012 American-Eurasian Network for Scientific Information
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 2012 Gale, Cengage Learning. All rights reserved.

Article Details
Printer friendly Cite/link Email Feedback
Title Annotation:Original Article
Author:Sharifi, Parisa; Amirnia, Reza; Majidi, Eslam; Hadi, Hashem; Moradi, Foad; Roustaei, Mozafar; Jafarz
Publication:Advances in Environmental Biology
Article Type:Report
Geographic Code:7IRAN
Date:Apr 1, 2012
Words:6155
Previous Article:Assessment of soil phosphorus availability affected by different amounts of phosphorus fertilizers in soils under sugarcane culture in Khozestan...
Next Article:Study of effect of refined waste water application on trend of changes in certain soil chemical properties in Khouzestan, Iran.
Topics:

Terms of use | Copyright © 2017 Farlex, Inc. | Feedback | For webmasters