جستجوی مقالات مرتبط با کلیدواژه « یونجه » در نشریات گروه « زیست شناسی »

cultivated alfalfa, which is known as green gold, is one of the best and most suitable fodder plants known in the world. Leaf weevil pest of alfalfa is considered as one of the limiting stresses in alfalfa production in the conditions of Iran.

In order to group pest tolerance in cultivated alfalfa, the traits of 30 alfalfa genotypes in the germplasm were evaluated in the training farm of Bu-ali Sina University.

The interaction between the varieties and the levels of pest attack showed significant differences in relation to weevil number, fresh forage yield, dry forage yield, plant height at the time of harvesting at1% and the amount of damage at 5% probability. The number of larva had significant positive correlation at a level of 5% with damage amounts. In stepwise regression, damage percent as dependent and other traits as independent variables were used. The results showed that larvae number, leaf chlorophyll extent and plant height with 30/01 cumulative coefficient explained the most variations of damage percent.

Considering to the percent of damage and the average comparison for other traits, Yazdi35 and Maoopa102 with the least number of larvae and the least percent of damage respectively and the highest height in attack or damage time as the most tolerance and cultivars Tak Buteh92 and MahalieMiandoab with the most larval number, damage percent and the lowest plant height were recognized as the most susceptible cultivars towards alfalfa weevil attack at damage time too.

Salinity stress is one of the most important environmental stress in the world and one of the important factors in reducing growth in many plants, especially in arid regions of the world. Salinity stress and increased sodium ion lead to the induction of oxidative stress and consequent cell death. Melatonin is a multiple function molecule spread in different plant and triggers several physiologic responses to different environmental stress. Exogenous application of melatonin to several plants can improve crop growth and development in response to many abiotic and biotic stresses with adjusting the antioxidant system of plants. Current studies reported that, the exogenous melatonin can increase plants' stress resistance by regulating both the enzymatic and non-enzymatic antioxidant defense process. In this study, the effect of melatonin on alfalfa roots under tissue culture condition was investigated. The aim of the present study was to investigate how melatonin regulated the antioxidant system and non-enzymatic antioxidants such as reduced glutathione and ascorbate under salt stress

In this study, alfalfa seeds (Medicago sativa) of the Isfahani variety were used and we studied the effect of melatonin and salinity stress on the alfalfa root. In order to sterilize the seeds, they were placed in a 70% ethanol solution for one minute and then in a 20% sodium hypochlorite solution for 20 minutes. After disinfecting the seeds, seeds were placed in each culture dish containing MS (Murashige and Skoog) culture medium. After germination, alfalfa seeds were transferred to MS culture medium containing concentrations of 0, 0.1, 10, and 15 micromolar melatonin and concentrations of 0, 150 and 200 mM salt. After 10 days of growth, total antioxidant capacity, the activity level of catalase, ascorbate peroxidase, superoxide dismutase, guaiacol peroxidase, and glutathione reductase, ascorbate and glutathione levels in alfalfa roots were measured.

Also, in the salinity stress, melatonin treatment significantly increased the total antioxidant power, while no significant difference was observed between different concentrations of melatonin, 0.1µM melatonin 82 درصد and 62 درصد raised antioxidant activity under 150 and 200 mM NaCl, so melatonin can reduce the levels of reactive oxygen species by scavenging of them through antioxidant enzyme or non- antioxidant system. Based on the results Melatonin treatment caused a significant increase in antioxidant power, the activity of CAT, APX, POD, SOD, GR enzymes, and antioxidant compounds in the glutathione-ascorbate cycle including DHA, ASC/DHA, GSH, and GSH/GSSG. along with increasing salinity concentration. On the other hand, salt stress increased oxidized compounds including DHA and GSSG in alfalfa roots. The data were carried out by two-way analysis of variance (ANOVA), followed by Duncan’s multiple range tests.

In addition to its direct role in clearing free radicals, melatonin activates the antioxidant defense system of the root, i.e. both antioxidant enzymes and antioxidant compounds in the ascorbate-glutathione cycle, which increases the resistance to damage oxidative effects caused by salinity stress in alfalfa root. These findings proposed that exogenous melatonin utilization dramatically activated ROS scavenging systems including enzymatic and nonenzymatic antioxidants to keep a relatively low amount of ROS and increased the tolerance of alfalfa root against salinity stress.

Alfalfa (Medicago sativa L.) is the most cultivated forage legume in Iran that productivity and quality of that are limited by salt stress. Melatonin as an indole amine was used for this study, with different concentrations of melatonin (0.1, 10 and 15 μM) under in vitro salt stress (150 and 200 mM NaCl) of alfalfa seedlings which by increasing salinity, growth rate as well as antioxidant power and synthesis of antioxidant compounds decreased. Growth parameters and defense system such as antioxidant enzymes were reduced in plants under salt stress. Exogenous utilization of melatonin in alfalfa significantly elevated fresh and dry weight, shoot length, photosynthetic pigments and carotenoid content. Melatonin application was augmented phenolic compounds such as total phenol, flavonoids and also antioxidant enzymes, phenylalanine ammonia-lyase (PAL) and tyrosine ammonia-lyase (TAL). According to our findings, Melatonin could be an excellent candidate for increasing salt resistance, by antioxidant capacity, scavenging ROS, reducing oxidative damage, augmented of non-enzymatic antioxidant such as phenolic compounds and on the other hand increasing the photosynthetic capacity of the plant by preserving photosynthetic pigments in alfalfa seedlings.

The alfalfa (Medicago sativa) plant was collected from the area of Andimeshk and in the spring of 2018. To express the 16S rDNA gene, the isolated bacteria were cultured in YMA environment under aerobic conditions and at a temperature of 25-28 °c. Genomic DNA localization was performed using the DNA extraction kit of SINA Gene Co. General and complete primers of sinobium bacteria were extracted from the NCBI site based on 16s rRNA gene sequences, and were used in sequencing the isolated bacteria genes in this study. The sequencing obtained by using Chromas Pro software was edited and compared using blasting software in NCBI database of three strains of alpha-alpha (Medicago sativa) were isolated and identified. The microscopic and macroscopic studies of the bacteria were identified. Bacterium 1 was identified as Gram-negative and caused by cream and embossed colonies, the second Gram-negative bacteria, with red-colored colonies and third bacterial colony isolated from the genus Alfalfa (Medicago sativa) plant. Sequencing results of 16S rRNA strains isolated from the Rhizoum species (Sequence ID = CP 021215.1) Sinorhizobium Meliloti (bacter1) (overlapping percentages 97 and game chats 2 percent), the second bacterium Sequence ID = CP-000738.1)) Sinorhizobium Medicae (bacteria 2) (the overlap percentage of 97 and 2-percent game chats) and third bacteria (Sequence ID = DQ-145546.1) Sinorhizobium meliloti (overlapping percentages 04.96 and 4% game chats) were identified.

Gaseous molecules hydrogen sulfide (H2S) and salicylic acid (SA) enhance plant acclimation to environmental stresses such as salt stress. In the current study, the effects of priming of alfalfa seeds with sodium hydrosulfide (NaHS) (0.75 mM) as H2S-donor or SA (0.75 mM) on the improvement of germination indicators and the growth of seedlings under salt stress (0, 25, 50 and 100 mM) and also the decline of oxidative damages caused by salt stress (0 and 50 mM) were evaluated. The results showed that under unprimed conditions, salt stress had negative effects on different indicators of alfalfa seed germination and also on the growth of alfalfa seedlings. In addition, under unprimed conditions, the accumulation of malondialdehyde (MDA) and hydrogen peroxide (H2O2) significantly increased under salt stress. NaHS-priming and SA-priming showed positive effects on germination indicators and root length significantly increased in the seedlings obtained from NaHS- or SA-primed seeds. NaHS-priming and SA-priming decreased the accumulation of MDA and H2O2 under salt stress conditions showing the effect of priming treatments in decreasing oxidative stress. In addition, in response to salt stress, NaHS-priming and SA-priming significantly increased the levels of total sugars (especially 1 and 3 days after germination), when compared with their levels under unprimed conditions. Therefore, NaHS-priming and SA-priming treatments enhance plant responses in the first days after germination against salinity by reducing oxidative damages through activation of the antioxidant defense systems.

Abstract Plants are frequently and naturally exposed by different of biotic and abiotic stresses including drought have negative effects on plant growth and yield. Symbiosis with mycorrhizal fungi is the broadest plant strategy for acclimation to environmental stresses. Hence in present study interaction of endomycorrhizal fungus and Pseudomonas aeroginosa, as Mycorrhizal fungi with Rhizobium meliloti in completely randomized blocks under three levels of irrigation and three replications wave examined. Spores of native endomycorrhizal fungus symbiont with medicago from Bagherabad region in Kerman are propagated by Zea mays and then used with mycorrhizal spores, Pseudomonas and Rhizobium separately and together in pots for three months under 3 different levels of irrigation, 70, 50, 20 persentage of field capacity. Results showed reduction of protein content but proline and reducing sugars concentration increased significantly under water stress. Changes in total nitrogen concentration were not significant. Inoculation with endomycorrhiza and bacteria significantly enhanced protein, proline, reducing sugars and nitrogen concentration under stress and without stress in comparison to control. In addition to, endomycorrhiza and bacteria had synergistic effect so that in many cases coinculation were more effective in relation to single inoculation. On the basis of these results, coinoculation with endomycorrhizal fungus, Pseudomonas aeroginosa and Rhizobium meliloti is suggested for increasing medicago tolerant to water stress.

Spotted alfalfa aphid (Therioaphis trifolii) is an important pest of alfalfa. In order to, study of proteome response to that aphid feeds, leaf sampling was made of alfalfa (Hamadani genotype) under treatment and control conditions. Leaf tissue proteome analysis, identified 208 protein spots detectable in staining by Coomassie blue. Of these, according to t- test, 16 spots were significantly different at 1% (P≤0.01). The protein spots with significant expression changes were searched by isoelectric point and molecular weight in databases and identified responsive possible proteins to pest stress conditions. Classification of identified proteins based on functional groups, showed that the highest of proteins change have been expressed in relation to stress, including this were protein disulfide isomerase, aldehyde dehydrogenase, heat shock proteins, polyphenol oxidase and proxiredoxins. The results revealed the activity of alfalfa at the level of protein expression to develop resistance to pest aphid spotted.

Medicago sativa L is from Fabaceae family that has several flavonoid compound in roots and shoots. Medicarpin is a dominant isoflvonoid that induces in nodul of root in different stage of developmentl. In this study, PAL (phenyl alanine amonialyase) activity was assayed using spectrophotometer. In this rse arc the concentration of medicarpin evaluete by HPLC (high performance liquid chromatography) were studied in different stages of development. The anatomical structure of leaves, stem, root and nodules were studied in transversal section by optical microscope. Different tissue such as epiderme, pharanshime, vascular systeme includes xylem and pheloem, were studied, measured and which are shown in different tabels.The results indicated that activity of PAL enzyme are altered during the plant development stage and changes of medicarpin content were correlated to the activity of PAL enzyme.The highest level of production of medicapin and activity of PAL enzyme have been observed during of growth in root.

Silicon (Si) has not been considered as an essential nutrient for plant growth however, it has been shown that supplying crops with adequate Si can improve environmental stress tolerance. On the other hand, exposure to toluene, as a hazardous organic pollutant widely found in the water resources, is an environmental stress for plants growing around many industries. The aim of this nutrient solution culture experiment was to investigate the effect of Si nutrition on alleviating injuries induced by toluene contamination on alfalfa (Medicago sativa L.). The plant seedlings supplied or unsupplied with 1 mM silicon (in the form of Na2SiO3.5H2O) were exposed for 30 days to three levels of toluene (0, 225, 450 mg L-1) in the nutrient solution. The results showed that shoot and root fresh mass, plant height, and root length significantly decreased in the present of toluene contamination. Exposure to toluene significantly decreased relative water content of the leaves, leaf photosynthetic pigments concentration, and Fe and Zn concentration in the shoot and root. Toluene contamination led to elevated peroxidation of root cell membrane. In the present of toluene, addition of Si enhanced water use efficiency, membrane stability, chlorophyll concentration and photosynthetic activity of the leaves. These changes induced by Si may lead to higher accumulation of Fe and Zn in the plant shoot.

Drought is one of the most important environmental stresses that adversely affect plant growth and crop production will In order to study a factorial randomized complete block design with three replications in greenhouse Ardabil University mohaghegh was conducted in 2013. Treatments were water stress at three levels: 35%, 55% and 75% field capacity and seed inoculated with mycorrhiza growth promoters (Glomus Mosseae), Rhizobium (Sinorhizobium meliloti), a mixture of both experienced and non-inoculated as results showed main effects and interaction between water stress and seed inoculation rates at 1% level of proline, soluble sugar, membrane stability, osmotic potential, plant height and leaf area was significantly influence of alfalfa, however lysine and methionine levels were changed only main effects. Increase the stiffness of proline, soluble sugar and decrease osmotic potential, membrane stability, lysine, stem height and leaf area were. Growth stimuli by increasing the production of metabolites and increased osmotic potential and membrane stability reduces the damaging effects of stress and increase plant height and leaf area were of alfalfa. Mycorrhiza and Rhizobium have performed better in most traits, but simultaneously they always showed the highest value. Also according to the regression equations in tension 85% proline and methionine had the highest share in the determination of cell water and the portion of the methionine reduces stress and enhances the contribution of soluble sugars and proline in determining the relative water content increases this increases the osmotic potential contribution in determining the relative water content in cells. Rhizobium and mycorrhiza mixture of proline and methionine, the highest share in determining the relative water content of the cells showed. Changes in leaf water content of a quadratic equation, but stem cells compared with less leaf area affected by the water content of cells Generally use a mixture of mycorrhiza and Rhizobium is always the best treatment for reducing stress have to show that there is a relationship between them Synvzhyst

In this research، seeds and seedlings of two alfalfa cultivars (Yazdi and Hamedani) were inoculated singly or in combination by strains of Sinorhizobium and Bacillus species and grown at 2 levels (0 and 100 mM NaCl) of salinity. Rhizobium strains were isolated from nodules of alfalfa plants and Bacillus was isolated from rhizosphere soils of fields in Isfahan-Dolatabad. Salt tolerant strains were detected by drop plate method on YMA and PVK culture medium containing 100 mM NaCl. Salinity increased electrolyte leakage and reduced fresh and dry weight of plants، chlorophyll a، b content، in both cultivars. Cultivar ''Hamedani'' was more sensitive to salinity compared to cultivar ''Yazdi''. Inoculation with Sinorhizobium and Bacillus improved plants growth، chlorophyll content and membrane stability under both non-saline and saline conditions compared with the non-inoculated control plants. Two bacterial strains acted synergistically، so that، co-inoculation was often more effective than single inoculation with Rhizobium or Bacillus. Our results suggest that inoculation by strains of these two bacterial species could help to alleviate salinity stress in alfalfa plant.

Heavy metal pollution is one of the most important ecological problems in the whole world. According to the environmental protection agency (EPA)، Pb is the most common heavy metal contaminant in the environment. In this study the effects of Pb stress (0، 120، 240، 500، 1000 μM Pb) on 7 days seedlings of Medicago sativa L. were investigated in hydroponic culture. The our results indicated Pb accumulation in roots and aerial parts and an increasing trend in total biomass was observed with increas of Pb concentration in medium which reduced later. Compared with control seedlings، increase in the contents of MDA and H2O2 were observed in those the seedlings under Pb stress. Moreover، increase in total flavonoids content، and peroxidase activity in roots and shoots of the treated seedlings were observed under Pb stress. Content of total phenolics decreased in roots and increased in shoots comparing to than the control.

Plants exposed to air pollution show returnable and unreturnable biochemical and physiological alterations. So biochemical parameters can provide valuable information about physiological condition of plants that are subjected to air pollution. This study was performed to determine the effects of air pollutants on the amount of proline، protein، calcium and phosphorus in Medicago sativa and Phaseolus vulgaris leaf and root. We also investigated M. sativa and Ph. vulgaris resistance to the air pollution in Arak Oil Refinery area. The plant samples were collected from polluted and non polluted area and the amount of proline، protein، calcium and phosphorus in leaf and root of plants were determined. The results showed that air pollution led to a significant increase of proline in leaf and roots of both M. sativa and Ph. Vulgaris. Air pollution also led to a significant increase of protein concentration in M. sativa (leaf and root)، but a significant decrease of protein concentration in Ph. vulgaris leaf and root. Concentration of calcium in M. sativa leaf and root under air pollution implied a significant increase. However air pollution caused a significant decrease of calcium in Ph. vulgaris root and no significant alteration of calcium rate in Ph. vulgaris root. Air pollution led to a significant increase of phosphorus rate in M. sativa root، but no significant alterations in M. sativa leaf، instead a significant increase of phosphorus rate in Ph. vulgaris leaf and root. In this study، increasing of protein and calcium in M. sativa plant was indicative of its resistance to the air pollution، and changes in biochemical parameters in Ph. vulgaris implied its sensitivity to the air pollution.

Rhizobia are able to fix atmospheric nitrogen and provide a significant amount of nitrogen in the soil. The purpose of this study was to isolate and identify the biochemical properties of indigenous Sinorhizobium meliloti bacteria in two regions of Iran, and also to detect the strains with higher efficiency, which have the potential to be used as bio-fertilizer. 

In this cross- sectional study, bacteria were collected from alfalfa plants in areas around Qom and Khorasan Provinces. These bacteria were identified using nodulation test, as well as biochemical and molecular examinations. The growth curves of these isolates were drawn. The isolates with higher efficiency were identified by inoculation of bacteria into alfalfa seeds and comparison of the rate of plant growth.

The isolated bacteria did not show a same reaction in Lithmus milk medium. All bacteria were gelatinase-negative, and only a few strains were able to utilize starch of the media. Some bacteria were able to grow in the presence of hydrophobic compounds. S22K and S36k from Khorasan, S3Q and S12Q from Qom showed better effects on the growth of test plants in comparison to other isolates.

The results of these research showed that some indigenous bacteria of S. meliloti are able to digest starch and were able to grow in the presence of SDS. Among the isolates, strains S3Q and S22K had the better potential for application as biological fertilizer. This research could be a step for the production of bio-fertilizers in our country.

ISSR markers were used to identify informative markers associated with traits plant high، chlorophyll content، total wet weight، total dry weight، leaf wet weight، leaf dry weight، stem wet weight، stem dry weight، number of leaves، number of stems and their ratio، ratio of leaf dry weight to stem dry weight and total dry weight to total wet weight in alfalfa populations. Sixteen ISSR primers amplified 117 loci among 80 alfalfa genotypes، with an average of 7. 3 loci per primer. Polymorphic information content (PIC) ranged from 0. 65 (UBC849) to 0. 93 (443)، with an average of 0. 77. Stepwise regression analysis between molecular data as independent variables، and morphological data as dependent variables was performed to identify informative markers associated with the studied traits. ISSR loci associated with total dry weight and leaf dry weight were the same. ISSR markers، Kourd and UBC849، were associated with number of leaves and leaf dry weight to stem dry weight، respectively. The maximum variation of chlorophyll content (82%) was accounted by UBC808، UBC812، UBC849، A12، 848، 425 and 456 markers while UBC808 and 425 markers accounted for 15% of the variation of the leaf wet weight. Since most of the used ISSR primers showed significant association with the studied traits، therefore، it is possible to use these markers along with morphological traits in alfalfa breeding programs for identification of suitable parents to produce mapping populations and hybrid varieties.

In this study, effects of Rhizobium on alfalfa plant growth under the SO2 pollution were evaluated 35 days plants (non-inoculated and inoculated with native or standard Rhizobium) exposed to the different concentration of SO2 (0, 0.5, 1, 1.5 and 2ppm) for 6 consecutive days for 2 hours per day. Results indicated significant decrease of Leaf area, stem length, root depth and fresh and dry weight of leaf, stem and root under high concentration of SO2. Number of leaves at all concentrations showed no significant change. Inoculation of alfalfa with Rhizobium significantly reduced the negative effects of high concentration of SO2. In this study, positive effects of native bacteria were impressive. The results indicate the harmful effects of high concentrations of SO2 pollution on growth of plants and the positive effects of bacterial inoculation on resistance to air SO2 pollution stress.

This study was carried out for evaluating morphogenesis responses of hypocotyl thin cell layers (TCL) of two alfalfas cultivars (Medicago sativa L. cv. Karysary and Rangelander) and also the effect of different 2,4-D concentrations on somatic embryogenesis was investigated. Sterilized seeds were cultured on SH medium without hormone. After a week, TCL (0.1 mm) obtained from hypocotyl segments were transferred to SH medium containing 2,4-D (1.5 mg/l). Produced calli were transferred to embryogenesis medium (SH medium containing four 2,4-Dconcentrations: 0, 5, 10, 15 mg/l) and one level of kin (1 mg/l). Then calli were transferred to regeneration medium (BOi2Y without hormone) and finally to the ½MS medium without hormone for plantlets growth. Callus induction was observed in all cultures of hypocotyl TCLs. After callus induction, the growth of the calli was performed suitability independent of the cultivar type. In regeneration medium, the somatic embryos appeared initially direct from TCL or indirect from callus as green dots that enlarged as the embryo develops through the globular, heart, torpedo and cotyledonary stages. The analysis of variance results showed that among different concentrations of 2,4-D there were significant differences in percentage of somatic embryogenesis (PSE) and number of somatic embryos per callus (NSC) (p<0.01). So that, maximum PSE and NSC occurred with 10 mg/l 2,4-D and minimum PSE and (NSC) without 2,4-D. PSE and NE (number embryogenesis) in Rangelander cultivar were significantly more than Karysary cultivar. Different concentrations of 2,4-D and cultivar × 2,4-D interaction had significant effect on plant regeneration (p<0.05). Plant regeneration was observed in SH medium of with and without 2,4-D. However, maximum plant regeneration was obtained in 5 and 10 mg/l of 2,4-D. Therefore, 2,4-D had the highest role on somatic embryogenesis from hypocotyl TCL.