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Home > Genetic Basis of Variable Cry1ac Expression in Indigenous Bt Cotton Genotypes

Genetic Basis of Variable Cry1ac Expression in Indigenous Bt Cotton Genotypes

Thesis Info

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Author

Khan, Muhammad Ibrahim

Program

PhD

Institute

University of Agriculture

City

Faisalabad

Province

Punjab

Country

Pakistan

Thesis Completing Year

2017

Thesis Completion Status

Completed

Subject

Plant Breeding & Genetics

Language

English

Link

http://prr.hec.gov.pk/jspui/bitstream/123456789/12965/1/Muhammad_Ibrahim_Khan_HSR_2017_UAF_26.03.2018.docx

Added

2021-02-17 19:49:13

Modified

2024-03-24 20:25:49

ARI ID

1676726282589

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Cotton is the mainstay of Pakistan’s economy with large area of Punjab and Sindh under its cultivation. Bollworms infestation is a big threat to cotton production as it causes severe yield losses. The development of transgenic cotton having Bt (Bacillus thuringiensis) gene producing δ-endotoxin was a success story to get control of bollworm infestation. Dark side of this story was the progressive development of resistant insects against this toxin. The spatio-temporal expression of the transgene is considered one of the reasons for resistant pests. Though the transgene is under the control of constitutive promoter, but expression is not consistent and stable throughout the growing season.Therefore, the present study was planned to examine the basis of the variable expression of Bt gene in the genetic background of local cotton accessions. In this research Bt cotton genotypes were screened at both DNA (qualitative) and protein (quantitative) level to identify the level of expression in various accessions with different genetic background. The results obtained revealed that FH-142 and VH-295 were the highest Cry1Ac expressing genotypes while IUB-222 and MNH-886 were the least. A set of 10 selected Bt genotypes were used to study the season long expression. The plants were sampled at different growth stages (i.e. 30, 60, 90, 120 and 150 days after sowing - DAS) and in different parts (Leaves and Bolls). Intra-plant expression variability was also assessed from upper, middle and lower canopy leaves. Enzyme Linked Immuno Sorbent Assay (ELISA) was performed for the quantification of Cry1Ac gene in the sampled tissues at protein level. The results revealed that 30 DAS leaves had the highest concentration while 150 DAS had the least expression. A gradual decrease in the expression was observed throughout the growing season among all the genotypes with the age of the plant. Leaves expressed higher expression as compared to bolls and other reproductive parts. Upper canopy leaves had considerable amount of δ-endotoxin protein whereas, middle canopy and lower canopy leaves showed a lower level of toxin. Same genotypes were exposed to three different sowing dates to analyse the effect of sowing dates on transgene expression. Significant effects were noticed among all the three sowing dates for Cry1Ac gene concentration. The expression of the transgene significantly reduced at 3rd sowing date due to an increase in temperature (i.e., 38 °C). The results provided the better understanding of Cry1Ac behavior in cotton plant under local climatic conditions. The inheritance pattern of the Cry gene and its associated yield and fiber quality traits were studied in the subsequent generations (P1, P2, F1, F2, BC1 and BC2). Two high Cry1Ac protein expressing genotypes (FH-142 and VH-295) were crossed with two low Cry1Ac protein expressing genotypes (IUB-222 and MNH-886) and with two non-Bt genotypes (VH-144 and MNH-786). Chi-square analysis for Cry1Ac gene revealed that its inheritance was controlled by single homozygous dominant gene. Most of the yield and fiber quality traits showed the involvement of additive, non-additive and epistatic type of gene action. The study provided guidelines for the development of better performing Bt cotton genotypes with standard toxin expression. Development of high expressing Cry1Ac genotypes with better yield and fiber quality traits is the ultimate solution to avoid insect pest losses and increased cotton production.
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شاہدہ جبین

شاہدہ جبین

کامریڈ شاہدہ جبین پاکستان پیپلز پارٹی کی پہچان ایک تصویر 1985ء اور دوسری 2018ء کی ہے ۔جنرل ضیاء الحق کے مارشل لاء سے لے کر اب تلک 40سالہ طویل جد وجہد کا سفر شاہی قلعہ لاہور سے لے کر پنجاب کی جیلوں میں قید و بند صعوبتیں ہی نہیںبرداشت کیں اپنی سات بہنوں کے بعد پیدا ہو نے والے 20سالہ نوجوان بھائی عثمان غنی شہید کی لاش کوٹ لکھپت جیل کے پھانسی گھاٹ سے اپنے کندھے پر اٹھا کر گھر لے کر آئیں جو جیوے جیوے بھٹو جیوے کے نعرے لگاتا تختہ دار پر گیا ۔آج جب پاکستان پیپلز پارٹی کی طرف سے سینٹ کی ٹکٹوں کے خواتین کے نام پڑھ رہا تھا تو سوچا کہ سینٹ کی ٹکٹ ہو یا قومی اسمبلی میں خواتین نشستوں پر نامزدگی کی صرف امراء اور جا گیرداروں بڑے سیاسی خاندانوں کی بیگمات ہی اس کی اہل ہوتی ہیں جن کا کام بن ٹھن کر منہ بند کر کے صرف نشستوں پر بیٹھنا ہو تا ہے ۔پاکستان پیپلز پارٹی یہ تو بڑے فخر سے کہتی ہے کہ آج جو جمہوریت ہے وہ شاہدہ جبین جیسے کارکنوںکی بدولت ہے مگر کس کے لیے اور کب تک ۔ پاکستان پیپلز پارٹی کے کارکنوں کو چاہیے کہ وہ اپنے حق اور شاہدہ جبین کے حق کے لیے آواز بلند کریں ۔

پاکستان پیپلز پارٹی کی قیادت اگر پنجاب میں اپنا کھویا ہوا مقام دوبارہ حاصل کر نا چاہتی ہے توکارکنوںکے سنگینوںکے سائے میں مارشل لاء کیخلاف جمہوریت کی بحالی کی تحریک میں انسانی آزادیوں کی جنگ لڑتے ہوئے ایک بھرپور آواز کامریڈ شاہدہ جبین جس کی آواز کو شاہی قلعہ کی بلند و بالا دیواریں بھی نہ دبا سکیں سلام ہے شاہدہ جبین کو اس لا زوال قربانیوں اور جد وجہد کو جو آج 40سال گزرنے...

الأسس والقرائن المنهجية الحديثية لتحقق العلم بالخبر: دراسة استقرائية في مصادر المصطلح وأقوال النقّاد

        The research methodology represents a scientific feature that highlights its manifestations and its fruits according to the nature and results of the methodology; this shows the intellectual contribution and impact on the advancement of human civilization in the scientific field.  The methodology of Muhaddithin provided an innovative and practical approach about the certainty of narations which they had devised and applied.           The question is: what is the way to document the narrations? To answer this question needs to refer to the books of sciences of Hadith, and when looking at these books shows that they are addressing this issue under different topics.           But the knowledge of narrations in terms of the factors pertaining to certainty is not covered in special sub title, but there are hints scattered in different places in the books of sciences of Hadith. There is still a need to address the issue comprehensively in all aspects relating the factors of certainty, Hence the goal of the research from the next two points 1- Exploration the foundations and factors pertaining to the certainty about the narrations. 2- Highlight the methodological innovation according to Muhaddithin in this regard. The purpose of this article is to provide a comprehensive overview of Methodological Bases and warranting Circumstances for Sunnah Authentication.

Molecular Characterization of Vibrio Cholerae Isolates from Pakistan

Cholera, a severe acute watery diarrhoeal disease, is caused by a motile, Gram-negative, bacillus named Vibrio cholerae. Millions of people around the globe died of cholera in the past. Cholera has remained endemic in South Asia and the first six pandemics have been considered to have originated from the Bay of Bengal. The favorable climatic conditions and contaminated water and food have maintained the disease in this region including Pakistan. In the last few years, WHO reported a significant increase in cholera cases around the world particularly in Haiti, Zimbabwe and Pakistan. The present study was carried out to characterize Vibrio cholerae isolates from Pakistan which involved determining the prevalence of different serogroups, phenotypic and genotypic characterization of associated antibiotic resistance, analysis of the cholera toxin (CTX) prophage, clonal relationship study, whole genome sequence analysis and single nucleotide polymorphisms (SNPs) based phylogeny. During this study (2009-2011), 113 V. cholerae O1 El Tor isolates were collected from cholera patients in different cities of Pakistan. Among these 113 isolates, 108 (96%) have O1 serogroup and El Tor biotype whereas the serotype was Ogawa. Serogroup O139 which used to exist in Pakistan and elsewhere in the past was replaced by O1 serogroup. All the isolates were resistant to sulfamethoxazole, trimethoprim, streptomycin and nalidixic acid. However, resistance to tetracycline, ampicillin, ceftazidime, erythromycin, cefotaxime, chloramphenicol and ciprofloxacin was seen in 63%, 19.5%, 7.2%, 2%, 01%, 06% and 01% isolates respectively, whereas all isolates were sensitive to ofloxacin. At the genotypic level SXT integrative and conjugative element (ICE), was present in all the isolates whereas integrons (class 1, 2 and 3) and qnrA, qnrB and qnrS for encoding quinolone resistance were absent in all the O1 El Tor isolates studied. Genetic basis of resistance to sulfamethoxazole, trimethoprim, streptomycin and tetracycline was analyzed by detecting sul2, dfrA1, strAB, tetA and tetA which were present in all the isolates showing resistance to the respective antibiotic respectively. florR was detected in about 37 isolates, however only six of them showed resistance phenotype for chloramphenicol. gyrA and parC were also studied for mutations responsible for quinolones resistance; all the isolates had transversions of AGT (underlined) and TCG (underlined) in codons 83 (substituting isoleucine for serine) and 85 (substituting leucine for serine) in case of gyrA and parC respectively, these mutations render bacteria resistant to quinolones. Year wise (2009- 2011) antibiotic analysis showed an increasing trend of antibiotic resistance which should be properly addressed by focusing on the standard treatment of cholera, rehydration therapy, whereas antibiotics should be prescribed only in case of severe dehydration. CTX prophage was analyzed by different PCRs and sequencing approaches. Cholera toxin which is the major virulence factor of V. cholerae was present in all O1 El Tor isolates except one isolate, CS15 from Charsada. All the isolates have ctxB of classical biotype. CTX prophage analysis revealed that all isolates have only one copy of CTXф located on the large chromosome, no tandem repeats of CTX prophage and RS1 were found and the order of RS1 and CTX prophage in the genome of V. cholerae O1 El Tor was: 5’-RSI-CTX prophage-3’. The frequency of heptanucleotide repeat (TTTTGAT) between ctxA and zot for ToxR binding in these isolates varied from 5 to 6 which is high in the region and frequently related to the toxin productivity of the isolates. Multi-locus variable number of tandem repeat analysis (MLVA) of V. cholerae O1 El Tor isolates based on five loci divided the 98 El Tor isolates into 47 sequence types belonging to six clonal complexes (CCs) and three singletons. Epidemiological data revealed that CC1 was associated with cholera cases all over the country in 2011 and Rawalpindi in 2009 whereas as V. cholerae O1 El Tor causing cholera in 2010 were associated with CC2, CC4 and CC3. Based on characteristic antibiotic resistance patterns and presence/absence of tagA and aldA, all V. cholerae O1 El Tor isolates were categorized in two groups, however MLVA generated clonal complexes did not reflected such relationship. The whole genome sequence analysis of the isolates and comparative genomics divided the V. cholerae O1 El Tor isolates from Pakistan in two categories. Genome wide SNPs analysis was carried out using the whole genome sequence data and a global phylogenetic tree was constructed comparing Pakistan Vibrio cholerae O1 El Tor isolates with 146 global and temporal representative V. cholerae isolates. All the O1 El Tor isolates from Pakistan were classified in two unique sub-clades named as Pakistan sub-clade 1 (PSC-1) and Pakistan sub-clade 2 (PSC-2) respectively. Both PSCs belonged to the third transmission wave of the current seventh pandemic. Both sub-clades possessed distinct antibiotic resistance patterns and were distinguished by signature deletions in Vibrio pathogenicity island -1 (VPI-1) and Vibrio seventh pandemic 2 (VSP- 2). All the PSC-1 isolates had a unique three gene (VC0819-VC0821) deletion in VPI-1 whereas in PSC-2 VPI-1 was intact. In PSC-1 a four gene (VC0495-VC0498) deletion was present in VSP-2 whereas a large 18 gene (VC0495-VC0512) deletion was present in VSP-2 of PSC-2. PSC-2 representing (4/4) and (31/38) isolates in 2009 and 2010 respectively was dominant in Pakistan whereas PSC-1 was only seen in Karachi representing (6/7) isolates. However in 2011, PSC-1 has apparently replaced PSC-2 representing 54/56 (96.5%) isolates and only 2/56 (3.5%) belonged to PSC-2. In nutshell, the study showed that two sub-clades with distinct antibiotic resistance patterns and genomic signatures circulating in Pakistan caused cholera during 2009-2011. Furthermore, SNPs based genetic markers can be used to track and identify the distribution of existing V. cholerae sub-clades or even any new type in future.