Home > Isolation and Identification of Causative Agent of Potato Common Scab and Characterization of Effective Antagonistic Bacteria As Biological Control of Disease.
Isolation and Identification of Causative Agent of Potato Common Scab and Characterization of Effective Antagonistic Bacteria As Biological Control of Disease.
Potato common scab (PCS) is an economically important and worldwide crop problem.PCS produces visible blemish lesions on the surface of tubers causing diminished quality and low market value. The severity of the lesions can be ranged from superficial raised brown to corky dark brown color with pustules or deep pitted scars which were few millimeters inside the tubers. The lesions may be small, discrete or covering large area of the tubers. Based on the severity of the lesions, common scab (CS) infected tubers sometimes unable for human consumption therefore causing severe economic loss to the growers. Common scab is caused by gram positive Streptomyces. The causal agent of PCS is Streptomyces scabies. Several other Streptomyces species including Streptomyces acidiscabies, Streptomyces europaeiscabies, Streptomyces turgidiscabies, Streptomyces stelliscabies and Streptomyces bottropensis are also reported as major PCS pathogens. In this study, CS infected tubers were collected from potato growing regions of Pakistan (Potato Research Institute, PRI Sahiwal and Lahore), Spain (A Coruna, Ourense, San Esteban and Lugo) and USA (Presque Isle and Orono, Maine). From Spain, almost one hundred and twenty-four bacterial isolates were isolated from CS infected tubers. Similarly, eighteen and ten bacterial isolates were isolated from CS infected tubers collected from USA and Pakistan, respectively. Among the bacterial isolates, twentyeight, thirteen and seven isolates were confirmed as scab-related Streptomyces spp. from Spain, USA and Pakistan, respectively after 16S rRNA analysis. Further identification of selected isolates was based on species specific primers PCR amplification. 16S-23S ITS region amplification, RFLP and phylogenetic analysis revealed four, two and one isolates belonged to S. turgidiscabies, S. scabies and S. stelliscabies, respectively from Pakistan. Similarly, from Spain, sixteen isolates were confirmed as S. europaeiscabies, six, four and two isolates were confirmed as S. turgidiscabies, S. bottropensis and S. stelliscabies, respectively and thirteen isolates were confirmed as S. scabies from USA. For antagonistic bacterial isolates, CS suppressive soil was collected from agriculture potato farms of Okara, Sahiwal and Lahore having no previous CS history over last five to ten years. From suppressive soil samples, five bacterial strains were isolated (A-1, A-2, A-4, A1RT and AC12AB) and screened on the basis of their antagonistic activity assessed by disk diffusion assay against CS isolates (S. scabies). Two best antagonistic bacterial isolates namely A1RT and AC12AB were selected on the basis of strong antagonistic activity against CS pathogens and promising results for plant growth promoting attributes including IAA (Indole-3-acetic acid) production, siderophores production, nitrogen fixation, potassium and phosphate solubilization. Antagonistic bacterial strains A1RT and AC12AB were evaluated to produce IAA quantitatively and qualitatively by colorimetric and HPLC methods, respectively. After 16S rRNA analysis bacterial isolate A1RT and AC12AB were identified as Streptomyces hygroscopicus and Streptomyces violaceusniger, respectively. CS pathogenic Streptomyces strains were analyzed for the presence of pathogenicity islets (PAI) including txtAB, tomA and nec1 genes by PCR amplification. Most of the pathogenic Streptomyces strains screened in this study were found to contain all three pathogenicity related genes like txtAB, nec1 and tomA. Methanolic extracts of Streptomyces hygroscopicus strain A1RT and Streptomyces violaceusniger strain AC12AB were purified with different chromatographic techniques including thin layer chromatography (TLC), silica gel chromatography, Sephadex column chromatography, solid phase extraction and preparative HPLC. The structure of purified compound was elucidated with help of one-dimensional (1H-NMR, 13C-NMR) and twodimensional NMR (1H/1H-COSY, HMQC and HMBC) techniques. The NMR experiment reveled the structure of bioactive compound as Isatropolone C and Azalomycin from antagonistic Streptomyces hygroscopicus strain A1RT and Streptomyces violaceusniger strain AC12AB, respectively. The plant experiments were conducted to check the in-vitro effect of antagonistic bacterial strains. Greenhouse assays were designed in Pakistan, Spain and USA which resulted significant decrease in CS disease severity and increase in number of shoots, shoot length, tuber weight and number of tubers. Finally, field trials were conducted in Pakistan with antagonistic Streptomyces hygroscopicus strain A1RT, Streptomyces violaceusniger strain AC12AB and combination of strain A1RT and AC12AB used as inoculum into the potato plants. About 84, 83, and 86.1% (p<0.05) PCS disease reduction was observed in field trials when S. scabies used with Streptomyces hygroscopicus strain A1RT, Streptomyces violaceusniger strain AC12AB and a combination of Streptomyces hygroscopicus strain A1RT and Streptomyces violaceusniger, strain AC12AB respectively and selected consortia also attributed significant increase in number of shoots, length of shoots, number of tubers and yield per hectare (p<0.05).In conclusion, the selected bacteria used in this study as a consortium, A1RT (Streptomyces hygroscopicus) and AC12AB (Streptomyces violaceusniger) may be used as an excellent biological control agent for decreasing the severity of CS infection and enhancing the growth of potato plants.
حب الوطنی نحمدہ ونصلی علی رسولہ الکریم امّا بعد فاعوذ بااللہ من الشیطن الرجیم بسم اللہ الرحمن الرحیم معزز اساتذہ کرام اور میرے ہم مکتب ساتھیو! آج مجھے جس موضوع پر اظہار خیال کرنا ہے وہ ہے:’’حب الوطنی ‘‘ صدرِذی وقار! جہاں تک حب اور محبت کا تعلق ہے تو کائنات رنگ و بو میں جتنا ذکر محبت کا ہوتا ہے شاید کوئی اور اصطلاح اتنی استعمال نہ ہوتی ہو ،کبھی کوئی اولاد سے محبت کا ذکر کرتا ہے۔ کبھی خوشبو سے محبت کا ذکر کیا جاتا ہے، کبھی دوستوں سے محبت کی پتنگیں بڑھائی جاتی ہیں،کبھی جائیداد سے محبت کا ذکر خیر ہوتا ہے بلکہ جائیداد کی محبت میں تو کشت و خون کا سلسلہ بھی روا رکھا جا تا ہے، سیم وزر سے محبت کی جاتی ہے۔ سونے چاندی کے اضانے میں اپنی تمام توانائیاں صرف کی جاتی ہیں، کوئی اولاد سے محبت کرتا ہے، کوئی مال سے محبت کرتا ہے، کوئی جان سے محبت کرتا ہے، اور وہ شخص کتنا خوش نصیب ہے جس کو اللہ اور اس کے رسولؐسے محبت ہوتی ہے۔ معزز سامعین! بحیثیت مسلمان ہماری حقیقی محبت کا تقاضا یہی ہے کہ ہماری محبت کے جملہ پہلو سرورِ کائنات کی ذات با برکات کے لیے ہوں۔ اور آپؐ کے ساتھ محبت اس بات کی بھی متقاضی ہے کہ آپ کے ہر قول وفعل کو من وعن تسلیم کیا جائے اور پھر ہر زاویے سے اس پر عمل کرنے کی کوشش کی جائے ، اس میں ہماری دنیوی و اُخروی کامیابی ہے۔ سرکارِ دو عالمؐ کا ارشاد گرامی قدر ہے کہ حب الوطن من الایمان کہ وطن سے محبت ایمان سے ہے۔ صدرِذی وقار! وطن کی محبت ایمان سے ہے اس کا اگر بنظر عمیق جائزہ لیں تو اسلام کے جملہ احکام بالخصوص اسی محبت کی تکمیل کے خواہاں ہیں۔...
We live in a global village. The cyber world has brought together people and shurnk the distences, yet multi cultural, multi ethinic and multi national has become the norm of the day. There is virtually no such place, no town, no village, city or state where people from diverse backgrounds speaking diffirent lagnuages and professing diffirent creeds live. This diveristy and variety is the essence of life. This paper analyzes various ways of establishing peace in the light of Islamic teachings. It finds out the causes of quarrels and disputes in different nations so that they may be prevented to make the world peaceful.
In recent years, the demand of polymers is growing progressively in a wide variety of fields extending from everyday life to medical and high technological applications due to their unique inherent properties like lightweight, flexibility, weather and corrosion-resistance and low cost. Considering the bulk properties of polymer an effort has been made to modify the structural, morphological, electrical and optical properties of near-surface layer of polymer by ion implantation. Indeed, it is a useful technique to modify surface properties of polymers without altering their bulk properties. In particular, with an improvement in electrical conductivity the implanted polymer can be utilized as a promising candidate for its future utilization in the field of plastic electronics. In the present study, the effects of 400 keV C+, Cr+ and Ag+ ion implantation on Polymethylmethacrylate (PMMA) have been examined at different ion fluences ranging from 5x1013 to 5x1015 ions/cm2. The ion penetration depths have been estimated with the help of SRIM simulation. The chemical and structural modifications in implanted PMMA are examined by Fourier Transform Infrared and Raman Spectroscopy (FTIR), respectively. The surface topographical examination of the implanted polymer has been performed using Atomic Force Microscope (AFM). The effects of ion implantation on electrical and optical properties of PMMA have been investigated by four probe apparatus and UV–Visible spectroscopic analysis. The FTIR spectra confirmed the formation of C = C bonds in C+ and Cr+ implanted PMMA at a fluence of 5 × 1015 ions/cm2 while for Ag+ implanted PMMA the peak for C=C is developed at relatively lower fluence of 1 × 1015 ions/cm2. Moreover, the Raman spectra justified the growth of sp2 carbon clusterization and transformation of C+, Cr+ and Ag+ implanted layer of PMMA into quasi-continuous amorphous carbon at implantation fluence of about ≥5x1014 ions/cm2. The AFM images showed the topographical modification due to ion implantation on PMMA. However, the extent of modification depends on the type of ions and increase in ion fluence. The roughness analysis revealed the smoothness of the surface of C+ and Cr+ implanted PMMA with increasing ion fluence. On the other hand, the implantation of Ag+ ions showed dominant effects on the surface of PMMA rather than C+ and Cr+ implantation. As a result, the surface of Ag+ implanted PMMA became rougher due to the formation of nano-hillocks and nano sized grainy structures above the surface. Due to ion-induced structural modifications the electrical conductivity of PMMA is increased to semiconducting range with a rise in ion fluence. After C+ ion implantation the electrical conductivity of PMMA is increased from 2.14 × 10-10 S/cm (pristine) to 1.46 × 10-6 S/cm. Similarly, for Cr+ and Ag+ ion implantation the electrical conductivity has improved to 7.21 × 10-6 S/cm and 9.60 × 10-6 S/cm, respectively. The results of UV-Visible analysis also confirmed an increase in sp2 carbon clusters in implanted PMMA in the favor of other results. Due to creation of carbonaceous clusters the optical absorption spectra of PMMA exhibit a shift towards higher wavelength after C+, Cr+ and Ag+ implantation along with a significant reduction in the optical band gap energies. For C+ implanted PMMA the optical band gap is reduced from 3.13 (pristine) to 0.66 eV whereas, after Cr+ and Ag+ ion implantation it shrinks to 0.85 and 0.81 eV, respectively.