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Home > Analysis of Bacterial Diversity in the Rhizosphere of Gm and Non- Gm Maize Crops and Plant Growth-Promoting Characterization of the Isolated Strains

Analysis of Bacterial Diversity in the Rhizosphere of Gm and Non- Gm Maize Crops and Plant Growth-Promoting Characterization of the Isolated Strains

Thesis Info

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Author

Naseer Ahmad

Program

PhD

Institute

Quaid-I-Azam University

City

Islamabad

Province

Islamabad.

Country

Pakistan

Thesis Completing Year

2013

Thesis Completion Status

Completed

Subject

Botany

Language

English

Link

http://prr.hec.gov.pk/jspui/bitstream/123456789/2362/1/2998S.pdf

Added

2021-02-17 19:49:13

Modified

2024-03-24 20:25:49

ARI ID

1676725479353

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The rhizosphere is a critical interface supporting the exchange of resources between plants and their associated soil environment. Rhizosphere microbial diversity is influenced by the physical and chemical properties of the rhizosphere, some of which are determined by the genetics of the host plant. However, within a plant species, the impact of genetic variation on the composition of the bacterial biota of GM and Non-GM maize rhizosphere is poorly understood. Here, we studied the bacterial diversity and population dynamics in the rhizosphere of one GM and two Non-GM maize varieties (IG and IW) grown under field conditions, by traditional cultivation techniques and 16S rRNA gene- based molecular analysis of DNA directly extracted from pre cultivated soil and rhizosphere samples. Rhizosphere and pre cultivated soil samples were taken at three different plant growth stages. The isolated bacterial strains were further screened for different functional characterization. Using pyrosequencing of bacterial 16S rRNA genes, around 160,000 sequences were obtained (20,000 reads per sample) representing 21 phyla''s, 184 families, 469 genera and a small amount of unclassified bacteria. The predominant bacterial groups in the rhizosphere of GM and Non-GM maize as well as in bulk soil were Proteobacteria (39.455%), Actinobacteria (24.453%), Bacteroidetes (11.990%), Firmicutes (7.532%) and Planctomycetes (4.478%). Other groups that were consistently found, although at lower abundance were Fibrobacteres, Thermi, Euryarchaeota, Tenericutes, Synergistetes and Thermotogae. There was no indication of consistent bacterial variation in the rhizosphere of GM and Non-GM maize as well as in bulk soil sample. We observed no significant variation in bacterial richness, diversity, and relative abundances of taxa between different growth stages of GM and Non-GM maize rhizosphere. Bacterial diversity in the rhizosphere of GM and Non-GM maize as well as bulk soil sample was explored using a culture based approach at different growth stages. A total of 52 bacterial strains were isolated from the rhizosphere as well as from bulk soil samples (different growth stages) and subjected to further analysis. Based on the analysis of the xxvi16S rRNA gene sequences, all the bacterial isolates were classified into four major phyla''s of the domain bacteria. The culturable component of the bacterial community revealed that the predominant groups were Firmicutes and Proteobacteria at Pre sowing stage). Proteobacteria, Bacteroidetes, Firmicutes and Actinobacteria (vegetative stage) and Firmicutes, Proteobacteria, Actinobacteria, Bacteroidetes (harvesting stage) were the pre dominant groups at different growth stages of GM and Non-GM maize rhizosphere. Zea mays, one of the most important cereals crop worldwide. The use of plant growth promoting (PGP) rhizobacteria may constitute a biological alternative to increase crop yield and plant resistance to diseases. In search for PGP rhizobacteria strains, all the cultured isolated bacterial strains (52) were in vitro screened for their PGP characteristics and biocontrol against plant pathogenic strains. Some of the bacterial isolates (different stages) were shown to produce indole acetic acid, phosphate solubilization, nitrate reduction and siderophore when tested in vitro for their plant growth promoting abilities. Their further application in a greenhouse experiment using Zea mays indicated that plant traits such as root and shoot elongation and biomass production, were influenced by the inoculation. Plant growth promoting traits of these strains indicated beneficial relationship between rhizobacteria and Zea mays plant. To understand the antagonistic potential, an in vitro antagonistic assay was performed to characterize and identify strains that were antagonistic to the plant pathogens Fusarium oxysporum, Aspergillus niger and Pseudomonas syringae, Xanthomonas axonopodis. Some of the strains (from different stages) exhibited in vitro inhibitory activity against the target plant pathogenic but none of the isolates were found to have antibacterial activity. Total 46 strains were screened (stages like pre sowing-14, vegetative-19 and harvesting-13) for enzymatic activities. Most of the isolates produced cell wall degrading enzymes. About isolates exhibited cellulase (43%), chitinase (43%), protease (54%), pectinase (63%) and lipase (70%). There was no significant variation in functional characterization of the isolates of GM maize rhizosphere as compared to their Non-GM counterpart.
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پروفیسرٹومس آرنلڈ

پروفیسر آرنلڈ
پچھلے مہینے کی علمی سوانح میں دو فاضلوں کی وفات کا سانحہ خاص طور سے اہم ہے، ان میں سے ایک مغرب نژاد اور دوسرا مشرقی تھا، پہلے کو ہندوستان اور ہندوستان کے مسلمان پروفیسر آرنلڈ کے نام سے جانتے ہیں، یہ فلسفہ کے عالم ہونے کے ساتھ عربی اور اسلامیات کے بھی ماہر تھے، یہ ہندوستان آکر پہلے اسلامیہ کالج لاہور میں فلسفہ کے پروفیسر مقرر ہوئے، اور پھر بعد کو محمڈن کالج علی گڑھ میں پروفیسر ہوکر آئے اور یہیں ان کی شہرت کا ستارہ چمکا، ان کی خاص خصوصیت علم کے ساتھ ان کا حسن اخلاق تھا، وہ مشرقی علماء کے ساتھ ہمیشہ گھل مل کر رہتے، اور لاہور ہو یا علی گڑھ ہر جگہ انھوں نے اپنے رفیق علماء سے کچھ سیکھا اور ان کو کچھ سکھایا، اور خصوصیت کے ساتھ لاہور میں قاضی ظفرالدین صاحب مرحوم اور علی گڑھ میں مولانا شبلی نعمانی مرحوم کے ساتھ ان کے دوستانہ اور علمی تعلقات رہے، اور ان واقعات کا نتیجہ لاہور میں ان کی تالیف السواء السبیل فی معرفۃ العرب والدخیل اور علی گڑھ میں ان کی مشہور تصنیف دعوت اسلام ہے۔
مولانا شبلی مرحوم اور ان میں تعلقات ٹھیک استاد اور شاگرد کے تھے، مگر یہ فیصلہ مشکل ہے کہ ان میں استاد کون اور شاگرد کون تھا، مولانا نے ان سے کچھ فرنچ سیکھی تھی، اور انھوں نے ان سے عربی ، مولانا مرحوم کے سفرترکی میں سمرناتک وہی رفیقِ سفر تھے، مولانا نے اپنے سفرنامہ میں اس کا حال لکھا ہے، سفر روم والے فارسی قصیدہ میں لکھتے ہیں،
آرنلڈ آنکہ رفیق است وہم استاد مرا
استاد کے استاد سے ۱۹۲۰؁ء میں لندن میں میری ملاقات ہوئی تھی، وہ اس وقت انڈیا آفس سے متعلق تھے، مولانا مرحوم کے تعلق کے سبب سے مجھ سے بڑی محبت سے پیش...

The Influence of Leadership Style on the Effectiveness of Office Management in Integrated Services Business Offices

The aim of this analysis was to ascertain the degree to which the Head of the Integrated Business Services Office's Leadership Style affects the efficacy of the Integrated Business Services Office's management. In data analysis, a descriptive study of one variable was performed to determine the percentage trend of each test variable; second, the commodity moment correlation formula was used to analyze variable relationships; and third, a basic equation model was used to analyze the impact relationship between the independent and dependent variables. The data for this study were processed using a micro statistical program with the assistance of a computer program. The data analysis and interpretation of the study's hypotheses indicate that there is a significant relationship and influence between the variable leadership style of the Integrated Business Services Office's Head and the effectiveness of the Integrated Business Services Office's management, at the 5% significance level or P = 0, 05, respectively.

Exogenous Use of Some Potential Organic Osmolytes in Enhancing Drought Tolerance in Maize Zae Mays L.

In the present study, a series of experiments were conducted in the Botanic Gardens of the Department of Botany, University of Agriculture, Faisalabad to test the relative effectivness of the three osmolytes in alleviating the adverse effects of drought stress on maize plants. The osmolytes were applied through different modes at different growth stages of maize plants under non-stress or water stress conditions. In the first experiment, varying levels (0, 30 and 60 mM) of each of the osmolytes were applied as foliar spray and presowing treatment of seeds of two cultivars (Agaiti-2002 and EV-1098). The plants raised from the treated seeds were grown in plastic pots filled with sandy loam soil under greenhouse conditions. After two weeks of the imposition of water stress, different levels (0, 30, and 60 mM) of each of the osmolytes were exogenously applied as a foliar spray to maize plants at the seedling, vegetative or both seedling and vegetative stages when grown under non-stress or water stress conditions (60% field capacity). Tween-20 (0.1%) was used as a surfactant for foliar spray. It was found that 30 mM of GB, or proline or trehalose was the most effective in promoting seedling growth under water stress conditions. However, GB and proline were more effective than trehalose in ameliorating the adverse effects of water stress on growth of both maize cultivars. It was found that effective concentration of exogenously applied osmolytes through seed soaking or through foliar application is 30 mM. During the 2 nd experiment the effective concentrations of these osmolytes (GB, proline and trehalose) as estimated from the 1 st experiment were applied as pre-sowing seed treatment and as foliar spray at different growth stages (seedling, vegetative and seedling+vegetative) as in the 1 st experiment to observe their effects in inducing drought tolerance maize plants in relation to various physiological and biochemical attributes. Exogenous application of osmolytes as presowing seed treatment or as foliar spray at different growth stages increased the photosynthetic rate of the plants of both cultivars that was associated with stomatal as well as non-stomatal factors. Plant water status as reflected by leaf water potential and leaf relative water content (RWC) was improved by the exogenously applied organic solutes and it was associated with leaf osmotic potential, endogenous GB and proline, which suggests the role of these osmolytes in osmotic adjustment. Exogenous application of these osmolytes increased the accumulation of nutrients particularly K, and shoot nutrient use efficiency in maize plants under water stress conditions. Exogenous application of compatible solutes enhanced the antioxidant capacity of drought stressed maize plants by increasing the activities of antioxidant enzymes (SOD, POD and CAT) and non-enzymatic compounds (phenolics, tocopherols and ascorbic acid) which is evident from the reduced MDA contents determined in the present study. Exogenously applied different osmolytes enhanced the seed and seed oil quality of both maize cultivars. Seed sugar, seed oil, seed protein, seed macro- and micronutriets increased due to exogenous application of these osmolytes. Moreover, improved seed oil quality was associated with enhanced oil unsaturation in terms of increased in oleic and linoleic acid contents as well as the oil lipophilic antioxidants (tocopherols, phenolics, flavonoids) which in-turn enhanced the oil antioxidant activity. Overall, exogenously applied different compatible solutes as a seed treatment or foliar application improved growth and yield of maize pants. Osmolyte-induced enhancement in growth and yield under water stress conditions was associated with increase in net CO 2 assimilation rate, plant water status, antioxidant capacity and nutrient accumulation, particularly of K. However, further studies are required to explicitly elucidate the mechanism of organic osmolytes influx through epidermis and target enzymes or metabolites to induce stress tolerance in plants. Moreover, further studies are important to work out cost-benefit ratios of the use of different organic osmolytes used in this study. This information will be undoubtedly beneficial for stakeholders, particularly the farmers.