Protein content started declining at 0. Decrease in total protein content may be due to increase in phenol content because many phenolic acids such as Ferulic acid, chlorogenic acid, vanillic acid, and p-coumaric acid are known to reduce the incorporation of certain amino acid into proteins and thus reduce the rate of protein synthesis [ 36 — 38 ]. Moreover, in salt- and water-stressed plant parts, the protein content also decreases owing to decreased rate of protein synthesis and increased rate of proteolysis [ 32 , 39 , 40 ].
Studies conducted so far indicated that stressful conditions alter the protein metabolism in plants and new stress specific proteins are synthesized in all different types of environmental stresses, such as salinity, drought, heat, chilling, anaerobiosis, pathogenesis, wounding, heavy metal toxicity, and gaseous pollutants [ 41 ].
It might be due to severe toxicity of heavy phytochemicals at increased extract concentration. Two polypeptides of These proteins might be involved in stress management of plants. Proline content of wheat leaves increased from 1. Proline content is positively correlated up to a significant level with stress severity which may be either due to inhibition of protein oxidation or due to breakdown of protein from its precursors [ 43 ].
Proline is also involved in intracellular osmotic adjustment [ 44 , 45 ]. Reactive oxygen species ROS are generated under stress conditions and antioxidant enzymes protect the cell structures against ROS [ 45 ]. Phytotoxins are proposed to work through the production of ROS and relative oxidative stress [ 46 ].
ROS are also known to trigger induction and expression of defense enzymes [ 45 ]. Production of soluble enzymatic and nonenzymatic antioxidants is one of the major protective means of the plant against ROS. Chemical defense against free radicals include compounds that are strong reducing agent such as glutathione, phenols, flavonoids, and polyamines [ 47 ].
Enzymatic defenses against free radicals include superoxide dismutase, catalase, peroxidase, phenol oxidase, and ascorbic acid oxidase [ 45 , 48 ]. The increased activity of both enzymes might be due to production of reactive oxygen or nitrogen species such as hydrogen peroxide and polyphenols, which further generate more free radicals.
Catalase scavenges hydrogen peroxide with water and dioxygen production nontoxic compounds [ 45 ]. Increased polyphenol activity was purposed to be a possible tolerance mechanism for plants under stress condition such as freezing and salt stress in C. Different types of allelochemicals also stimulated many antioxidant enzyme activities in response to high level of free radicals in Lycopersicon esculentum [ 50 ].
Intercropping of compatible crops is the need of hour to fulfill the increased dietary demand of an increasing population. Intercropping of poplar with wheat is beneficial for farmers to some extent. But senescence leaves of poplar adversely affect the seedling growth and other biochemical properties of wheat. Therefore, required improvement and care should be taken in using intercropping approach of poplar and wheat, so that only beneficial properties are utilized and harmful properties are avoided.
The authors declare that there is no conflict of interests regarding the publication of this paper. This is an open access article distributed under the Creative Commons Attribution License , which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Article of the Year Award: Outstanding research contributions of , as selected by our Chief Editors. Read the winning articles. Journal overview. Special Issues. Academic Editor: Antonio Ferrante. Received 31 Jul Revised 06 Nov Accepted 05 Dec Published 24 Dec Abstract Triticum vulgare Wheat based products are the major dietary source of food in developing countries.
Introduction Wheat Triticum spp. Material and Methods 2. Extract Preparation of Senescence Leaves of Poplar Collected leaves were dried at room temperature for 8—10 days. Seed Germination Wheat seeds were surface sterilised with 0. Measurement of Seed Germination The wheat seed germination rate was determined by measuring root and shoot lengths, percent germination, and germination index [ 9 ]: Inhibition percentage due to senescence poplar leaves was calculated using the following modified equation [ 10 ]: 2.
Estimation of Chlorophyll and Carotenoids Chlorophyll and carotenoid contents of wheat leaves were determined spectrophotometrically [ 11 ]. Estimation of Total Phenol The total phenol content of wheat leaves was estimated by Folin-Ciocalteu method [ 13 ]. Protein Estimation Total protein content was estimated by the method of Lowry et al. Proline Content Proline content was measured using ninhydrin reagent [ 16 ]. Assay of Antioxidant Enzymes 2.
Catalase CAT, E. Polyphenol Oxidase EC 1. Statistical Methods All results were analysed using descriptive statistical techniques such as mean standard deviation.
Physiological Effects Germination studies revealed a decrease in germination index with increase in concentration of poplar senescence leaves PSL. D of three different experiments.
Table 1. Root, shoot length, and germination index of wheat seeds in the presence of PSL extract. Figure 1. Effect of PSL extract on chlorophyll content a and carotenoid content b of wheat. Different letters mean statistical differences at. Figure 2. Effect of PSL extract on sugar contents of wheat. You can also search for this author in PubMed Google Scholar. Correspondence to Guoping Zhang. Reprints and Permissions.
Jabeen, Z. Difference in physiological and biochemical responses to salt stress between Tibetan wild and cultivated barleys. Acta Physiol Plant 37, Download citation. Received : 26 February Revised : 09 July Accepted : 22 July Published : 08 August Anyone you share the following link with will be able to read this content:.
Sorry, a shareable link is not currently available for this article. Provided by the Springer Nature SharedIt content-sharing initiative. Skip to main content. Search SpringerLink Search. Abstract Soil salinity is one of the m ajor abiotic stresses affecting crop growth and yield worldwide. References Ayalew L, Katsuhara M Insights into the salt tolerance mechanism in barley Hordeum vulgare from comparisons of cultivars that differ in salt sensitivity.
For 10 d, plantlets were kept in growth chambers and daily exposed to 5-h temperature treatments. At the control temperature, this ratio was greater than 0. The leaf chlorophyll contents a, b, and total of the three studied rice cultivars under the daytime temperature treatments are presented in Figure 3. Overall, leaf chlorophyll pigments a, b, and total remained unchanged for the studied cultivars; however, of the cultivars studied, concentrations of these pigments were lowest in 'F'.
Figure 2. Figure 3. Respiration rate The Cultivar x Heat stress treatment interaction produced significant changes in the plant respiration rate in the three studied rice cultivars Figure 4. Figure 4. By contrast, proline concentration remained unchanged in 'F60' rice plants over this temperature range Figure 5. Figure 5. Assessment of membrane stability based on electrolyte leakage and lipid oxidation MDA content Assessing the effect of the different daytime temperatures on membrane stability based on the percentage of electrolyte leakage revealed that 'F60' and 'F' seemed to be the most susceptible.
However, 'F' plants did not exhibit changes in membrane stability throughout the heat stress treatment. The effect of treatments on MDA concentration confirms our previous results. Figure 6. Figure 7. Studies performed by Taniyama et al. Cao et al. This effect was particularly evident in 'F60' rice plants Figure 4.
These observations are in agreement with those of Jagadish et al. Previously, Almeselmani et al. One of the acclimation mechanisms of 'C' is to maintain a high net photosynthetic rate and a low respiration rate under heat stress conditions. We observed similar tolerance mechanisms in 'F'.
Plant acclimation to heat stress has been frequently assessed based on changes in biochemical markers such as MDA and proline Jouve et al. Tang et al. Proline can also function as a respiration substrate Britikov et al. In effect, the rapid metabolism of this amino acid likely provides energy for mitochondrial respiration Hare and Cress, The MDA content is an important tool for defining the degree of lipid peroxidation, as a higher content of this compound indicates more severe damage of the cell membrane Heath and Packer, Similar results were observed in rice plants by Zhang et al.
When subjected to heat stress, the rice 'F60' exhibited a significant decrease in the photosynthetic rate coupled to a higher respiration rate and proline accumulation, as well as greater membrane stability damage elevated concentrations of malondialdehyde and large electrolyte losses.
These results can provide an explanation of agronomic performance of 'F60' susceptible and 'F' tolerant under heat stress conditions. In consequence, the use of the techniques applied in the present study may provide support to rice breeding programs aiming to select heat stress-tolerant cultivars for Colombian agriculture. Ahmed, J. Evaluation of seedling proline content of wheat genotypes in relation to heat tolerance.
Bangladesh Journal of Botany Deshmukh, and V. Effects of prolonged high temperature stress on respiration, photosynthesis and gene expression in wheat Triticum aestivum L. Plant Stress Allen Jr. Contrasting crop species responses to CO 2 and temperature: rice, soybean and citrus. Vegetatio Waldren, and I. Rapid determination of free proline for water-stress studies.
Plant and Soil Pot, F. Maas, and A. Effects of different light treatments on the nocturnal transpiration and dynamics of stomatal closure of two rose cultivars. Scientia Horticulturae Vladimirtseva, and N. Interestingly, antioxidant activity in shoot and root of the wheat genotypes was observed to be of the same level.
The SV of 0 for a parameter indicates the least relative value observed for that parameter, and the SV of 1 for a parameter indicates the highest relative value observed for that parameter. Comprehensive assessment of the wheat genotypes ranked HD at fourth position indicating it to be the most salt-sensitive. Kharchia was ranked first with the SV of 1 for most 14 out of 15 of the parameters.
To investigate the effect of salt stress on transcription of HKT s and to correlate it with salt tolerance ability of the wheat genotypes, relative expression of three HKTs was examined. One of the candidate genes TaHKT1;4 shows root-specific expression with a well-defined functions Kumar et al.
In root, the gene was observed to be downregulated under the stress in all the four genotypes Figure 7C. The gene was observed to be downregulated in shoot of Kharchia 8.
The gene was found to be downregulated maximum 2. The results are mean fold change in relative expression over the control with three biological and three technical replicates, normalized with actin reference gene expression.
Bars represent standard deviation. Alignment of the cloned partial sequences of HKT1;4 gene KR, KR from the most contrasting salt-responsive genotypes Kharchia and HD indicated that the gene contains 2 deletions, 6 transitions, and 12 transvertions in HD Figure 8. The point mutations observed in TaHKT1;4.
Alignment of amino acid sequences of TaHKT2;3. At the first place, Isoleucine was substituted by Valine, at the second position the Valine was substituted by Alanine, at the third position substitution was from Serine to Threonine, and at fourth position Valine was substituted by Isoleucine. However, no detectable effects of the mutations could be seen on the structure of the protein Figure Alignment of amino acid sequences of TaHKT1;4. By contrast, TaHKT1;4.
However, conserved domains analysis for the TaHKT1;4. Homology model of HKT2;1. Conserved domain analysis of the partial TaHKT2;1. Homology modeling of TaHKT2;3. Conserved domain analyses for the partial TaHKT2;3.
The last quarter of the gene body, used for quantitative analysis of 5mC, was observed to contain context-specific variation in 5mC Figure The coding region of TaHKT2;1 second quarter of the gene body used for quantitative analysis of 5mC was found to contain variations in 5mC content with respect to the genotypes, tissues, and salt stress Figure Salt stress further increased the methylation level in these contexts.
Increase in 5mC content was observed in Kharchia in all the three contexts under salt stress, but the maximum percent increase was observed in the CG context Figure 13C.
Similarly, increase in 5mC content was observed in all three contexts in the root of both the genotypes under salt stress Figures 13B,D , but the total methylation was higher in case of Kharchia Coding region of the TaHKT2;3 first quarter of the gene body used for the quantitative analysis of 5mC showed variations in 5mC content with respect to the genotypes, tissues, and salt treatments Figure Therefore, subsequent experiments were carried out with mM NaCl for 14 days to study the various changes occurring initially the plants as adaptive measures, and to assess their potential of acclimatization under the stress.
Morphological symptoms, biochemical and physiological responses of the wheat genotypes revealed that stress treatment with mM NaCl for 14 days was most appropriate for comparative evaluation of the wheat genotypes Figure 1 and Supplementary Table S1. The available literature corroborated our finding as we found that mM NaCl has been commonly used for evaluation of salt tolerance of different plant species including wheat Tammam et al.
Hence, salt treatment with mM NaCl for 14 days was used in the subsequent experiments. Kharchia Sairam et al. Stress imposition for 14 days followed by observations on plant height, number of tillers and leaf senescence Figure 1 and Table 1 provided an indication about salt tolerance ability of the wheat genotypes. However, the result was subjected to verification based on certain physio-biochemical traits.
Changes in leaf-area, shoot-root biomass ratio and dry matter yield due to the stress corroborated the above observations on salt tolerance ability of the wheat genotypes. Accumulation of excessive salts in photosynthetic tissues has been reported earlier to cause decrease in leaf-area and senescence of leaf Rauf et al.
Effects of salt stress on plant biomass have been suggested to be an important criteria for evaluating salt tolerance in crop plants Bao et al. No significant reduction in total chlorophyll content in Kharchia, but significant reduction in the other genotypes, supported better salt tolerance ability of Kharchia By contrast, with maximum reduction in total chlorophyll content of HD the genotype emerged as the most salt-sensitive Figure 3A.
The observed effect of salt stress on chlorophyll content is in agreement with those reported earlier in kidney bean, cabbage, and different species of wheat Rauf et al.
Production of ROS is intimately related with the stressful conditions which leads to the membrane damage and electrolyte leakage Kumar et al. Therefore, lipid peroxidation and MSI were used to assess salt tolerance ability of the different genotypes Supplementary Tables S1, S2. These results are in agreement with the findings of Rao et al. In fact, cellular machinery releases compatible solutes to maintain redox potential under the stress.
Increased accumulation of soluble sugar in shoot and proline Figure 4 was in agreement with the earlier observations of Romero-Aranda et al. Intriguingly, a significant reduction in soluble sugar was observed in root of the wheat genotypes which substantiate the observation of Wu et al.
The increased concentration of compatible solutes might be one of the key factors in alleviating the stress either via osmotic adjustment or by conferring desiccation resistance. Accumulation of phytophenolics, besides proline and soluble sugar, had been reported earlier to maintain cellular homeostasis under abiotic stresses. To examine the effect of salt stress on production of phytophenolics, TPC was measured.
Significant increase in TPC in shoot and root, except in case of HD, was in agreement with the findings of Elhamid et al.
With constitutively high antioxidant activity and increased TPC, Kharchia could maintain higher antioxidant potential protecting itself from the free-radicals generated under the stress. Athar et al. Strong correlation between antioxidant activity and accumulation of TPC was reported by Rao et al. Our observations clearly indicate that other components e. However, under the stress it got transported to or effluxed out of the leaf in case of Kharchia and KRL to maintain its optimum level.
Kharchia could maintain mineral ion homeostasis and confronted least damage due to the stress, while HD encountered the maximum Figure 1 and Supplementary Tables S3. Comparative evaluation of salt tolerance ability of the bread wheat genotypes based on a multivariate, comprehensive analysis clearly indicated Kharchia to be more salt-tolerant than KRL On the other hand, HD was identified to be the most salt-sensitive based on the above parameters.
Salt stress causes biochemical, physiological, epigenetic, and several other molecular changes in plants which can be correlated with differential expression of the stress-associated gene s. TaHKT1;4 , reported to be root-specific Kumar et al. This might be one of the reasons for the observed salt-sensitive nature of HD and WH Davenport et al. Thus, 2. We were particularly interested to know the role of genetic and epigenetic components in differential expression of the HKT s in the contrasting wheat genotypes under salt stress.
Root-specific differential expression of HKT1;4 in the contrasting genotypes Figure 7A and structural variations Figures 10A,C could be correlated with salt tolerance ability of Kharchia and hypersensitivity of HD Platten et al. Considering the importance of these motifs, and their absence in TaHKT1;4. By contrast, HKT2;1 and HKT2;3 showed only minor structural variation Figure 11 , but significant difference in their expression in root and shoot of the contrasting wheat genotypes under salt stress.
Therefore, the possible role of epigenetic changes in differential expression of the HKTs was investigated. The coding region of TaHKT1;4 showed only a minor variation in 5mC content with respect to the salt stress, tissues and genotypes Figure More importantly, the variation in 5mC content could neither be correlated with the differential expression of TaHKT1;4 nor with the salt tolerance level of the wheat genotypes.
0コメント