Table of Contents

Volume 2, Issue 3

  June - December 2011

  Pages 135 - 224

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MEETING REPORT

Bt rice evaluation and deployment strategies

P. Manimaran, G. Ramkumar, M. Mohan, S. K. Mangrauthia, A.P. Padmakumari, P. Muthuraman, Bentur J.S., B.C. Viraktamath and Sena M. Balachandran
Pages 135 - 137
http://dx.doi.org/10.4161/gmcr.2.3.19213
Abstract | PDF

Bacillus thuringiensis (Bt), a gram positive soil bacteria was first identified and named by Japanese Microbiologist Shigetane Ishiwata in 1901. During sporulation Bt produces proteinaceous parasporal crystal proteins called δ-endotoxins, or Cry proteins, which are insecticidal. Numerous Cry proteins have been isolated and characterized from different Bt strains with activity against insects, mites and nematodes. Sprayable formulations containing these Cry proteins as active ingredients have contributed significantly in the field of insect pest management. Since the first cloning of cry genes from Bt,1 scientists have successively demonstrated that plants could be genetically engineered to express these cry genes for the control of dreadful insect pests. Eventually, the first transgenic crop expressing Btcry1Ac gene in cotton was approved in 1996 for commercial cultivation in the USA to manage bollworms.




REVIEWS

Coexistence between conventional, organic and GM crops production: The Portuguese system

Alessandro Chiarabolli
Pages 138 - 143
http://dx.doi.org/10.4161/gmcr.2.3.18476
Abstract | PDF

The objective of this paper is to analyze the way of Portugal is addressing the issue of the coexistence between conventional, organic and Genetically Modified (GM) crops production. In the EU, no form of agriculture, be it conventional, organic or transgenic, should be excluded. Farmers are free to choose the production type they prefer, without being forced to change patterns already established in the area and without spending more resources. Farmers’ choice of growing GM or non-GM crops depends not only on technical aspects related to the productivity gains and agronomic benefits to be gained from adopting this technology, but also on consumers’ preferences. Today only few Member States have adopted specific legislation on coexistence. Portugal was one of the first European Country that, in 2005, adopted a coexistence law and it has implemented one of the most complete systems of coexistence regulation. Today Portugal has a well-balanced regime based on free choice for consumers and growers. It has a coexistence system complete regulation and farmers who wish to cultivate GM maize must fulfill with national coexistence legislation that includes the following compulsory rules: participate in specific coexistence training courses, register the cultivation area, inform by written notification about their intent to cultivate GM, apply measures of coexistence, among others.

Genetic engineering in Cowpea (Vigna unguiculata): History, status and prospects

Cristiane T. Citadin, Abdulrazak B. Ibrahim and Francisco J. L. Aragão
Pages 144 - 149
http://dx.doi.org/10.4161/gmcr.2.3.18069
Abstract | PDF

In the last three decades, a number of attempts have been made to develop reproducible protocols for generating transgenic cowpea that permit the expression of genes of agronomic importance. Pioneer works focused on the development of such systems vis-à-vis an in vitro culture system that would guarantee de novo regeneration of transgenic cowpea arising from cells amenable to one form of gene delivery system or another, but any such system has eluded researchers over the years. Despite this apparent failure, significant progress has been made in generating transgenic cowpea, bringing researchers much nearer to their goal than thirty years ago. Now, various researchers have successfully established transgenic procedures for cowpea with evidence of inherent transgenes of interest, effected by progenies in a Mendelian fashion. New opportunities have thus emerged to optimize existing protocols and devise new strategies to ensure the development of transgenic cowpea with desirable agronomic traits. This review chronicles the important milestones in the last thirty years that have marked the evolution of genetic engineering of cowpea. It also highlights the progress made and describes new strategies that have arisen, culminating in the current status of transgenic technologies for cowpea.

Approaches for gene targeting and targeted gene expression in plants

Amjad Masood Husaini, Zerka Rashid, Reyaz ul Rouf Mir and Bushra Aquil
Pages 150 - 162
http://dx.doi.org/10.4161/gmcr.2.3.18605
Abstract | PDF

Transgenic science and technology are fundamental to state-of-the-art plant molecular genetics and crop improvement. The new generation of technology endeavors to introduce genes 'stably' into 'site-specific' locations and in 'single copy' without the integration of extraneous vector 'backbone' sequences or selectable markers and with a 'predictable and consistent' expression. Several similar strategies and technologies, which can push the development of 'smart' genetically modified plants with desirable attributes, as well as enhance their consumer acceptability, are discussed in this review.




RESEARCH PAPERS

Open Access Article

Production cost analysis and use of pesticides in the transgenic and conventional corn crop [Zea mays (L.)] in the valley of San Juan, Tolima

Kelly Ávila Méndez, Alejandro Chaparro Giraldo, Giovanni Reyes Moreno and Carlos Silva Castro
Pages 163 - 168
http://dx.doi.org/10.4161/gmcr.2.3.17591
Abstract | PDF

A survey of 10 producers of conventional corn (Hybrids PAC 105 and Maximus) and 10 producers of transgenic corn (Pioneer Hybrid 30T17) was carried out in the municipality of Valle de San Juan in the territorial division of Tolima (Colombia), in order to analyze the differences in production costs and environmental impacts of these two agricultural technologies.  The environmental impacts were determined by calculating the field “Environmental Index Quotient” (EIQ). In the production cost analysis, a difference of 15% was found in benefit of the transgenic technology. The structure of costs of the transgenic technology was benefited by the reduced use of pesticides (insecticides and herbicides). In regards to production, the transgenic technology showed a greater yield, 5.22 ton/ha in comparison to 4.25 ton/ha the conventional technology, thus a 22% difference in yield. Finally, the EIQ calculation showed quantitative differences of 196.12 for the conventional technology (EIQ insecticides 165.14 + EIQ herbicides 30.98), while the transgenic technology was of 4.24 (EIQ insecticides 0 + EIQ herbicides 4.24). These results show a minor environmental impact when using the transgenic technology in comparison to the conventional technology, in regards to the use of insecticides and herbicides in a temporal, spatial and genotypical context analysis. 


Open Access Article

Performance of broiler chickens fed diets containing DAS-68416-4 soybean meal

Rod A. Herman, Christina M. Dunville, Daland R. Juberg, Dale W. Fletcher and Gary L. Cromwell
Pages 169 - 175
http://dx.doi.org/10.4161/gmcr.2.3.17869
Abstract | PDF

Broiler chickens are a fast growing monogastric animal commonly used to evaluate the equivalence between transgenic and non-transgenic grains as part of the human safety assessment process. While commonly viewed like other livestock feeding trials, such studies are performed with transgenic crops with input traits (that are not designed to improve nutrition) to aid regulatory authorities in evaluating safety. Studies of this type are actually more similar to toxicology studies in purpose, with sensitive endpoints like growth used to detect metabolic perturbations. DAS-68416-4 soybean expresses the aryloxyalkanoate dioxygenase-12 (AAD-12) enzyme which inactivates 2,4-diclorophenoxyacetic acid (2,4-D) and provides DAS-68416-4 soybeans tolerance to this herbicide. DAS-68416-4 also expresses the phosphinothricin acetyltransferase (PAT) enzyme from Streptomyces viridochromogenes which confers tolerance to glufosinate-ammonium herbicides. A 6-week broiler study was conducted with diets containing toasted DAS-68416-4 soybean meal (40, 36, and 32% in starter, grower and finisher diets, respectively) to evaluate nutritional wholesomeness and safety compared with conventional comparators. Toasting soybean meal is required to inactivate endogenous antinutrients making soybean suitable for consumption by monogastric animals like broiler chickens. Toasting was found to denature both the AAD-12 and PAT proteins rendering them non-detectable by enzyme linked immunosorbent assays. Broiler growth and performance parameters were measured over a 6-week period of exposure to diets containing different sources of toasted soybean meal, and results indicate that DAS-68416-4 soybean is nutritionally equivalent to non-transgenic soybean.

In vitro root induction of faba bean (Vicia faba L.)

Roba M. Ismail, Heba E. M. Elazab, Gihan M. H. Hussein and Emad A. Metry
Pages 176 - 181
http://dx.doi.org/10.4161/gmcr.2.3.18003
Abstract | PDF

A major challenge for regeneration of faba bean (Vicia faba L.) plants is the difficulty of in vitro root induction. In the present study, in vitro rooting and its architecture have been studied. Adventitious root formation was successfully induced from regenerated faba bean shoots of four Egyptian cultivars, i.e., Giza 461, Giza 40, Giza 834 and Giza 716 on hormone free MS medium supplemented with 5 mg/l silver nitrate. Among the four cultivars, Giza 461 and Giza 40 were recorded as the highest root formation response (75 % and 65) followed by cultivars Giza716 and Giza843 (20%, and 10%). Anatomical study proved that the produced roots are initiated as the adventitious lateral root (LR) with tri-arch xylem strands as compared with the penta-arch of the primary roots of the intact faba bean seedling. The obtained results overcome the root induction problem in faba bean.

Establishment of regeneration and transformation system in Egyptian sesame (Sesamum indicum L.) cv Sohag 1

Amal F. Al-Shafeay, Ahmed S. Ibrahim, Mohamed R. Nesiem and Mohamed S. Tawfik
Pages 182 - 192
http://dx.doi.org/10.4161/gmcr.2.3.18378
Abstract | PDF

Sesame (Sesamum indicum L.) is an important oil crop in many tropical and sub-tropical regions of the world, yet has received little attention in applying modern biotechnology in its improvement due to regeneration and transformation difficulties. Here within, we report the successful production of transgenic fertile plants of sesame (cv Sohag 1), after screening several cultivars. Agrobacterium tumefaciens- carrying the pBI121 plasmid {neomycin phosphotransferase gene (NPTII) and a β-glucuronidase gene (GUS)} was used in all experiments. Recovery of transgenic sesame shoots was achieved using shoot induction medium (Murashige and Skoog MS basal salt mixture + Gamborg’s B5 vitamins + 2.0 mg/l BA + 1.0 mg/l IAA + 5.0 mg/l AgNO3 + 30.0 g/l sucrose + 7.0 g/l agar + 200 mg/l cefotaxime and 25 mg/l kanamycin) and shoots were rooted on MS medium + B5 vitamins + 1.0 mg/l IAA + 10.0 g/l sucrose and 7.0 g/l agar. Rooted shoots were transplanted into soil and grown to maturity in greenhouse. Incorporation and expression of the GUS gene into T0 sesame plants was confirmed using polymerase chain reaction (PCR), reverse transcriptase-PCR (RT-PCR) and GUS histochemical assay. Several factors were found to be important for regeneration and transformation in sesame. The most effective were plant genotype and the addition of AgNO3 for successful recovery of sesame shoots. Co-cultivation time and optical density of the Agrobacterium were also critical for sesame transformation. This work is an attempt to open the door for further genetic improvement of sesame using important agronomic traits.

Efficient transformation and regeneration of transgenic cassava using the neomycin phosphotransferase gene as aminoglycoside resistance marker gene

Michael Niklaus, Wilhelm Gruissem and Hervé Vanderschuren
Pages 193 - 200
http://dx.doi.org/10.4161/gmcr.2.3.18866
Abstract | Full Text | PDF

Cassava is one of the most important crops in the tropics. Its industrial use for starch and biofuel production is also increasing its importance for agricultural production in tropical countries. In the last decade cassava biotechnology has emerged as a valuable alternative to the breeding constraints of this highly heterozygous crop for improved trait development of cassava germplasm. Cassava transformation remains difficult and time-consuming because of limitations in selecting transgenic tissues and regeneration of transgenic plantlets. We have recently reported an efficient and robust cassava transformation protocol using the hygromycin phosphotransferase II (hptII) gene as selection marker and the aminoglycoside hygromycin at optimal concentrations to maximize the regeneration of transgenic plantlets. In the present work, we expanded the transformation protocol to the use of the neomycin phosphotransferase II (nptII) gene as selection marker. Several aminoglycosides compatible with the use of nptII were tested and optimal concentrations for cassava transformation were determined. Given its efficiency equivalent to hptII as selection marker with the described protocol, the use of nptII opens new possibilities to engineer transgenic cassava lines with multiple T-DNA insertions and to produce transgenic cassava with a resistance marker gene that is already deregulated in several commercial transgenic crops.

Open Access Article

Seeds of a Possible Natural Hybrid between Herbicide-Resistant Brassica napus and Brassica rapa Detected on a Riverbank in Japan

Mitsuko Aono, Seiji Wakiyama, Masato Nagatsu, Yukio Kaneko, Toru Nishizawa, Nobuyoshi Nakajima, Masanori Tamaoki, Akihiro Kubo and Hikaru Saji
Pages 201 - 210
http://dx.doi.org/10.4161/gmcr.2.3.18931
Abstract | PDF

Transgenic herbicide-resistant varieties of Brassica napus, or oilseed rape, from which canola oil is obtained, are imported into Japan, where this plant is not commercially cultivated to a large extent. This study aimed to examine the distribution of herbicide-resistant B. napus and transgene flow to escaped populations of its closely related species, B. rapa and B. juncea. Samples were collected from 12 areas near major ports through which oilseed rape imports into Japan passed—Kashima, Chiba, Yokohama, Shimizu, Nagoya, Yokkaichi, Sakai-Senboku, Kobe, Uno, Mizushima, Kita-Kyushu, and Hakata—and the presence of glyphosate- and/or glufosinate-resistant B. napus was confirmed in all areas except Yokohama, Sakai-Senboku, Uno, and Kita-Kyushu. The Yokkaichi area was the focus because several herbicide-resistant B. napus plants were detected not only on the roadside where oilseed rape spilled during transportation but also on the riverbanks, where escaped populations of B. rapa and B. juncea grew. Samples of B. napus that were tolerant to both herbicides were detected in four continuous years (2005–2008) in this area, suggesting the possibility of intraspecific transgene flow within the escaped B. napus populations. Moreover, in 2008, seeds of a possible natural hybrid between herbicide-tolerant B. napus (2n = 38) and B. rapa (2n = 20) were detected; some seedlings derived from the seeds collected at a Yokkaichi site showed glyphosate resistance and had 2n = 29 chromosomes. This observation strongly suggests the occurrence of hybridization between herbicide-resistant B. napus and escaped B. rapa and the probability of introgression of a herbicide-resistance gene into related escaped species.




REPORT

Open Access Article

Regulatory considerations surrounding the deployment Of Bt-expressing cowpea in Africa: Report of the deliberations of an expert panel

Joseph Huesing and 21 others
Pages 211 - 224
http://dx.doi.org/10.4161/gmcr.2.3.18689
Abstract | Full Text | PDF

Cowpea (Vigna unguiculata spp unguiculata) is adapted to the drier agro-ecological zones of West Africa where it is a major source of dietary protein and widely used as a fodder crop. Improving the productivity of cowpea can enhance food availability and security in West Africa. Insect predation – predominately from the legume pod borer (Maruca vitrata), flower thrips (Megalurothrips sjostedti) and a complex of pod-sucking bugs (e.g., Clavigralla spp) – is a major yield-limiting factor in West African cowpea production. Dramatic increases in yield are shown when M. vitrata is controlled with insecticides. However, availability, costs, and safety considerations limit pesticides as a viable option for boosting cowpea production. Development of Bt-cowpea through genetic modification (GM) to control the legume pod borer is a promising approach to cowpea improvement. Cowpea expressing the lepidopteran-active Cry1Ab protein from Bacillus thuringiensis is being developed as a first generation Bt-cowpea crop for West Africa. Appropriate stewardship of Bt-cowpea to assure its sustainability under West African conditions is critical to its successful development. A first step in this process is an environmental risk assessment to determine the likelihood and magnitude of adverse effects of the Cry1Ab protein on key environmental protection goals in West Africa. Here we describe the results of an expert panel convened in 2009 to develop the problem formulation phase for Bt-cowpea and to address specific issues around gene flow, non-target arthropods, and insect resistance management.