Genetically Modified Cultivars Research Articles

Productivity, nutritive value, and profitability of high-digestibility alfalfa cultivars harvested at two stages of development in eastern Canada

Alfalfa ( Medicago sativa L.) cultivars developed for improved digestibility by conventional breeding or genetic modification have not been evaluated in eastern Canada. This study compared yield, nutritive value, and profitability of two reduced-lignin genetically modified (GM) cultivars, three conventionally selected for low lignin or high pectin, and one population with improved stem degradability, with two commercially adapted cultivars as controls. Alfalfa was harvested at the early bud (intensive management) or early flower (extensive management) stage of development during the first post-seeding year at three sites and the second post-seeding year at one site. All cultivars/populations had similar annual dry matter (DM) yields, except for the lower DM yield (−20%) of the improved stem degradability population. Conventionally selected cultivars for improved digestibility did not differ from control cultivars for in vitro DM digestibility (IVTD) and neutral detergent fiber digestibility (NDFd). Reduced-lignin GM cultivars, however, had a greater IVTD and NDFd (+10%) and less lignin (−10%) than control cultivars at the same stage of development. Reduced-lignin GM cultivars under extensive management had similar NDFd and greater annual DM yield (+1 to 2 Mg DM ha−1), but reduced total digestible nutrients (−41 to 44 g kg−1 DM), in comparison to control cultivars under intensive management. Using partial budget analysis, the comparison of more digestible GM cultivars to the control cultivars resulted in an increase in annual farm net profits ranging from CAD$7.40 to $79.60 cow−1 year−1 depending on stage of development at harvest. Further investigations are needed to quantify the performance of dairy cows fed cultivars with improved digestibility.

Plant genome modification: from induced mutagenesis to genome editing.

The snowballing growth of scientif ic data obtained using modern techniques of genome editing (GE) calls for their critical evaluation and comparison against previously applied methods such as induced mutagenesis, which was a leading method of genome modif ication for many decades of the past century, and its application has resulted in a huge diversity of cultivars. However, this method was relatively long and included a number of stages from inducing multiple mutations using different mutagenic factors to crossing and selecting the most valuable cultivars for several generations. A new technology of genetic engineering and transgenesis enabled us to radically reduce the time required to obtain a new genetically-modif ied cultivar to one generation and make the modif ication process more effective and targeted. The main drawback of this approach was that an introduced transgene might uncontrollably affect the other genes of a recipient plant, which led to the limitations imposed on transgenesis application in many countries. These limitations have been effectively surmounted thanks to the development of GE techniques allowing for a precise modif ication within a single gene that in many characteristics make it similar to a natural allele (especially when it comes to ribonucleoprotein complexes), which has paved the way for wide application of GE in routine breeding. The paper reviews the main stages of GE development in its application in plants. It provides short descriptions of different GE techniques, including those using protein editors such as zinc-f inger and transcription activator-like effector nucleases (TALEN), and the CRISPR/Cas9 technology. It lists a number of achievements in using GE to produce new cultivars of higher yield that are resistant to unfavorable factors and have good nutritional properties. The review also considers the de novo domestication approach, which allows for faster obtaining of new cultivars from natural varieties. In the conclusion, the future ways of GE development are discussed.

Adaptability, stability and environmental stratification of genetically and nongenetically modified corn in the Cerrado

ABSTRACT Crop yield depends on interaction between genetic and environmental factors, making it essential to study adaptability, stability and environmental stratification in order to mitigate the effects of this interaction. Four experiments were conducted to assess competition between corn cultivars in the 2018/19 growing season, two in Paraíso do Tocantins and two in Palmas, with sowing performed on November 5, 2018 and January 15, 2019. Cultivar-environment interaction was analyzed in genetically modified (GM) and non-GM commercial corn cultivars in the Vale do Araguaia region of Tocantins state (TO), Brazil, A randomized block design was used for all the experiments, in 3 × 12 factorial scheme, with three doses of nitrogen fertilizer as topdressing (50, 100 and 150 kg of N ha-1) and 12 commercial cultivars (six non-GM, 1CHD, 2CV, 3CV, 4CV, 5CTH, 6CDH and six GM, 7GTH, 8GTH, 9GSH, 10GSH, 11GSH, 12GSH. For statistical analysis, the N dose in each experiment represented a different environment. The characteristic studied was grain yield, using the adaptability and stability methods as well as environmental stratification. Different responses were observed between the GM and non-GM cultivars. Most of the GM and non-GM cultivars were better adapted to favorable and unfavorable environments, respectively. All the environments exhibited similar behavior regardless of location, sowing time and the N dose used, demonstrating that fewer environments can be used in future breeding research.

Comparison of growth and aflatoxin B1 production profiles of Aspergillus flavus strains on conventional and isogenic GM-maize-based nutritional matrices

Maize grown in both North and South America are now predominantly genetically modified (GM) cultivars with some resistance to herbicide, pesticide, or both. There is little information on the relative colonisation and aflatoxin B1 (AFB1) production with maize meal-based nutritional matrices based on kernels of non-GM maize and isogenic GM-ones by strains of Aspergillus flavus. The objectives were to examine the effect of interacting conditions of temperature (25–35 °C) and water availability (0.99–0.90 water activity, aw) on (a) mycelial growth, (b) AFB1 production and (c) develop contour maps of optimum and marginal conditions of these parameters for four strains of A. flavus on three different non-GM and isogenic GM-maize based nutritional media. The growth of the four strains of A. flavus (three aflatoxigenic; one non-aflatoxigenic) was relatively similar in relation to the temperature × aw conditions examined on both non-GM and GM-based matrices. Optimum growth overall was at 30–35 °C and 0.99 aw for all four strains. Under water stress (0.90 aw) growth was optimum at 35 °C. Statistically: non-GM, GM cultivars, temperature and aw all significantly affected growth rates. For AFB1 production, all single and interacting factors were statistically significant except for non-GM × GM cultivar. In conclusion, colonisation of GM- and non-GM nutritional sources was similar for the different A. flavus strains examined. The contour maps will be very useful for understanding the ecological niches for both toxigenic and non-toxigenic strains in the context of the competitive exclusion of those producing aflatoxins.

Selection of ideotype to increase yield potential of GM and non-GM rice cultivars

Using classical breeding, plant breeders envision a plant type whose yield they aim to enhance by selecting for individual traits to create model/ideal plants or ideotypes. To achieve this, those factors restricting yield need to be identified and controlled through the use of new technologies to achieve the desired ideotype. This study aimed to determine the ideotype of seven genetically modified (GM) and non-GM rice (Oryza sativa L.) cultivars. Field experiments were carried out in three isolated regions in the north of Iran under the Iranian bio-safety standard protocol. Four of the GM cultivars carried the cry1Ab gene in the vegetative stage while three non-GM cultivars served as the control. R2 values showed that five, six and seven variables in Sari, Amol and Rasht regions accounted for 63 %, 52 % and 74 % of paddy yield variation, respectively. In the same three regions, paddy yield variation due to white heads accounted for 28.38 %, 8.45 % and 3.95 % of the total variation in paddy yield, respectively. The total estimated variation in paddy yield in Sari, Amol and Rasht was 1810.50, 2377.6 and 2176.47 kg ha−1, respectively. Average data over the three regions indicated that highest loss in paddy yield was observed in non-GM ‘Nemat’, ‘Khazar’ and ‘Tarom Hashemi’. GM cultivars derived from ‘Khazar’ showed significantly lower paddy yield loss than the non-GM parent. Dead heart, a condition that occurs in the vegetative stage in which the stem borer larva enters the stem and feeds on the growing shoot, causing the central shoot to dry, as well as white heads, which is a condition in which whole ear heads of adult plants become dry and yield chaffy grains, in all three regions were important variables contributing to paddy yield loss. In the future, producing GM rice resistant to striped stem borer with an active promoter in the reproductive growth stage might allow farmers to reduce a significant part of paddy yield loss resulting from white heads, which is directly negatively correlated with filled spikelets per panicle (R2 = -0.57**), in order to achieve an ideotype.

Assessment of the life cycle of genetically modified and non-genetically modified rice cultivars

The release of environmental emissions, which partly emanates from the application of chemical inputs, is a major global concern. Planting crops that have been genetically modified (GM) is one possible solution for reducing negative impacts on the environment and human health. The life cycle of genetically modified (GM) and non-GM rice cultivars was assessed. Four GM lines (derived from a backcross of ‘Khazar’ cultivar with ‘Tarom Molaii’, a GM line) and conventional cultivars (non-GM parents) were cultivated under a standard biosafety protocol in three isolated regions in the north of Iran. In order to conduct a life cycle assessment analysis, at first, the results of low- and medium-yielding cultivars in each region were analyzed separately. Since there were no differences among the impact categories and indices in different regions, the average for the results of the three regions is presented. Results show that decreased application of pesticides in GM cultivars led to less energy utilization, emission of greenhouse gases, and global warming potential (GWP). The highest amount of GWP, cumulative non-renewable energy demand, terrestrial acidification, freshwater eutrophication, marine eutrophication, and water depletion were observed in the non-GM cultivars. The heavy metals emitted in air (Pb, Cd, Zn, and Hg) and water (Cr, Zn, Cu, Cd, Hg, Pb, and Ni) were less in GM cultivars than in non-GM cultivars. Pollutants emitted from soil (nitrate, metals, and pesticide) in GM cultivars derived from ‘Khazar’ were less than their non-GM parent. As a result, we conclude that the level of emission of environmental emissions is directly related to the application of input and method of field management, which was based on the lowest level of these indices obtained when GM cultivars were produced. Therefore, the emissions released from environmental issues are positively correlated with the application of inputs and field management practices.

Effects of Chinese honeybee foraging on oilseed rape gene flow and honey ingredients

SUMMARYHoneybee foraging can transfer exogenous genes from genetically modified (GM) oilseed rape (Brassica napusL.) to closely related plants, which not only induces potential ecological risks but also contaminates non-GM seeds or honey products with GM ingredients. These events may lead to international trade disputes. Chinese honeybees (Apis cerana ceranaFabricius) and a herbicide (glufosinate)-resistant GM strain ofB. napus(Z7B10) were studied to examine the effects of honeybee short-range foraging on oilseed rape gene flow and honey ingredients. Results showed variable frequencies of gene flow between GM and non-GM oilseed rape cultivars, with the highest frequency under nylon net isolation with artificially stocked honeybees, the lowest frequency under nylon net isolation alone, and an intermediate frequency under natural pollination, suggesting the important role of honeybee foraging in gene flow frequency. Additionally, GM pollen grains were found in honey collected from honeybees foraging on both GM and non-GM oilseed rape cultivars. The phosphinothricin acetyltransferase protein was also detected in both unbroken pollen-containing and pollen-free honey by protein testing strips, suggesting that honeybee foraging on GM oilseed rape could lead to contamination with GM ingredients. Overall, the results provide a direct scientific basis for the ecological risk assessment and safety management of GM oilseed rape.

Considerations for Managing Agricultural Co-Existence between Transgenic and Non-Transgenic Cultivars of Outcrossing Perennial Forage Plants in Dairy Pastures

Many of the major forage species used in agriculture are outcrossing and rely on the exchange of pollen between individuals for reproduction; this includes the major species used for dairy production in grazing systems: perennial ryegrass (Lolium perenne L.) and white clover (Trifolium repens L.). Cultivars of these species have been co-existing since contrasting cultivars were developed using plant breeding, but the consequences and need for strategies to manage co-existence have been made more prominent with the advent of genetic modification. Recent technological developments have seen the experimental evaluation of genetically modified (GM) white clover and perennial ryegrass, although there is no current commercial growing of GM cultivars of these species. Co-existence frameworks already exist for two major cross-pollinated grain crops (canola and maize) in Europe, and for alfalfa (Medicago sativa L.) in the US, so many of the principles that the industry has developed for co-existence in these crops such as detection techniques, segregation, and agronomic management provide lessons and guidelines for outcrossing forage species, that are discussed in this paper.

Ex-Ante Economic Impact Assessment of Genetically Modified Banana Resistant to Xanthomonas Wilt in the Great Lakes Region of Africa.

BackgroundCredible empirical evidence is scanty on the social implications of genetically modified (GM) crops in Africa, especially on vegetatively propagated crops. Little is known about the future success of introducing GM technologies into staple crops such as bananas, which are widely produced and consumed in the Great Lakes Region of Africa (GLA). GM banana has a potential to control the destructive banana Xanthomonas wilt disease.ObjectiveTo gain a better understanding of future adoption and consumption of GM banana in the GLA countries which are yet to permit the production of GM crops; specifically, to evaluate the potential economic impacts of GM cultivars resistant to banana Xanthomonas wilt disease.Data SourcesThe paper uses data collected from farmers, traders, agricultural extension agents and key informants in the GLA.AnalysisWe analyze the perceptions of the respondents about the adoption and consumption of GM crop. Economic surplus model is used to determine future economic benefits and costs of producing GM banana.ResultsOn the release of GM banana for commercialization, the expected initial adoption rate ranges from 21 to 70%, while the ceiling adoption rate is up to 100%. Investment in the development of GM banana is economically viable. However, aggregate benefits vary substantially across the target countries ranging from US$ 20 million to 953 million, highest in countries where disease incidence and production losses are high, ranging from 51 to 83% of production.ConclusionThe findings support investment in the development of GM banana resistant to Xanthomonas wilt disease. The main beneficiaries of this technology development are farmers and consumers, although the latter benefit more than the former from reduced prices. Designing a participatory breeding program involving farmers and consumers signifies the successful adoption and consumption of GM banana in the target countries.

Effects of GM potato Modena on soil microbial activity and litter decomposition fall within the range of effects found for two conventional cultivars

Plant roots have a profound effect on soil microbial activity, particularly in the rhizosphere. Hence, it is important to understand the potential effects of genetically modified (GM) crops on soil microbial activity and related processes such as litter decomposition. In this study, we compared the effects of GM potato Modena on soil microbial activity and carbon (C) and nitrogen (N) mineralization to effects induced by Modena’s parental isoline (Karnico) and a conventional potato cultivar (Aventra). A field experiment was conducted at two sites to assess microbial catabolic diversity (using MicroRespTM) in the rhizosphere and in bulk soil, during flowering and senescence of the potato plants. In a laboratory experiment with soil and potato litter from the field experiment, we investigated whether the cultivars had modified the activity of soil microbial communities to such an extent that this affected C and N mineralization. Results of the field experiment showed no GM-induced effects on microbial catabolic diversity, while effects of field site location and sampling date were significant. Multivariate analysis including plant traits and soil characteristics revealed that microbial catabolic activities in rhizosphere soil were strongly correlated with soil organic matter and tuber sucrose content, whereas in bulk soil, they were primarily correlated with soil moisture. In the laboratory experiment, we found that Modena induced a “home-field advantage” in N mineralization, yet this effect was inconsistent across locations and was also observed for other cultivars. Based on our data and results from previous studies, we conclude that the effects of GM cultivar Modena on soil microbial activity and litter decomposition fall within the normal range of effects found for conventional potato cultivars.

Genomics and breeding of Brassicaceae crops

Brassicaceae crops include oil crops, vegetables, condiments, fodder crops, and ornamental plants. Most of these crops belong to or are closely related to the genus Brassica. The Brassicaceae also includes the most intensively studied model plant, Arabidopsis thaliana. In molecular genetic studies of Brassicaceae crops, information on A. thaliana genes is highly useful, and many genes important for plant breeding have been identified. Different species of Brassica have various numbers of chromosomes. The genome relationship of three monogenomic species and three digenomic species that are well known as U’s triangle was discovered in Japan, and relationships between different genera have also been studied (Mizushima 1980). In these studies, interspecific and intergeneric hybridizations have been performed, and some interspecific and intergeneric hybrids have been used as breeding materials. Studies on interspecific and intergeneric hybridization are reviewed by Kaneko and Bang in this special issue. Genome synteny relationships between different species in Brassica and closely related genera are complicated, as exemplified by the different numbers of chromosomes between species. The monogenomic species of Brassica and closely related genera have three copies, on average, of genes homologous to each A. thaliana gene, indicating whole genome triplication in the evolution of the ancestral species of Brassica and closely related genera. The recent development of next-generation sequencers has accelerated the determination of whole genome sequences from many species. A draft sequence of the Brassica rapa genome was published in 2011 (Wang et al. 2011), and whole genome sequences of other species of Brassicaceae crops will also be published soon. The progress with genome studies of Brassicaceae crops and genome relationships between them are described by Ashutosh et al. Many Brassicaceae crops have self-incompatibility, which is not common in other seed-propagated crops. Self-incompatibility is a commonly found trait in many angiosperm species, but self-compatible plants have been selected as crops. The genetics and molecular mechanisms of self-incompatibility have been most intensively studied using Brassica species, and this trait is also used as a tool for producing F1 hybrid seeds of Brassicaceae vegetables. Recent studies on Brassica self-incompatibility are introduced by Kitashiba and Nasrallah. On the other hand, the trait most widely used for F1 hybrid seed production in many crop species is cytoplasmic male sterility. Cytoplasmic male-sterile lines can be obtained by interspecific hybridization and repeated backcrossing with a paternal species, and this form of sterility is considered to be caused by incompatibility between the cytoplasm and nucleus. Cytoplasmic male sterility in Brassicaceae crops is discussed here by Yamagishi and Bhat. Brassicaceae crops generally contain glucosinolates, which are degraded to isothiocyanates by the endogenous enzyme myrosinase after disruption of cells. Isothiocyanates are pungent compounds, probably important for defense against herbivores, and they determine the taste or quality of vegetables, condiments, and feed. These compounds are reported to have anti-carcinogenic activity; therefore, Brassica vegetables are in the spotlight for medicinal uses. Studies on glucosinolates in Brassicaceae vegetables are presented by Ishida et al. Because of water deficit in farmland, probably due to global warming, drought tolerance has become increasingly important in rapeseed breeding. Drought is frequently accompanied by salinity; therefore, recent studies on rapeseed breeding for drought and salt tolerance are reviewed by Zhang et al. Furthermore, herbicide-tolerant cultivars developed by genetic engineering are an increasing percentage of rapeseed produced around the world. For the production of these genetically modified (GM) cultivars, pollen-mediated gene flow from GM cultivars to wild plants or landraces should be limited. Recent studies on the possibility of pollen-mediated gene flow from GM cultivars of rapeseed are described by Tsuda et al. After the Great East Japan Earthquake, the Rapeseed Project for Restoring Tsunami-Salt-Damaged Farmland was started by Tohoku University because of the high tolerance of Brassica crops to salinity. This project has been supported by Kureha Corporation and other companies. The cost of publication of these reviews is partially supported by this project.

Field evaluation of the effects of cotton variety and GM status on rhizosphere microbial diversity and function in Australian soils

Despite the high level of adoption of genetically modified (GM) cultivars in the Australian cotton production system, concerns remain over the use of GM technology, particularly with regard to potential non-target effects. To address the hypothesis that GM cotton causes shifts in rhizosphere microbial diversity or function, we assessed rhizosphere soil samples from a range of conventional and GM cotton cultivars for diversity of bacteria and fungi, populations of ammonium oxidisers, rhizosphere basal and selective substrate-induced respiration, and non-symbiotic N2 fixation and nitrification. Comparison of results for GM and conventional cotton cultivars, both between and within seasons, indicated that the cotton rhizosphere plant–microbial interactions are variable in nature and significantly influenced by cultivar type. The GM status of the plant did not result in rhizosphere bacterial or fungal DNA-based grouping, but MicroResp data did show some grouping based on GM status, although this was not consistent by trait, suggesting that the GM trait is not greater than cultivar selection in causing rhizosphere change, especially when measured in the field environment with all the associative management practices.

Genomics for drought resistance – getting down to earth

A meta-analysis of 520 reports published during the last 20 years on transgenic and mutant plants generated towards drought resistance revealed a total of at least 487 tested transgenic plants involving at least 100 genes claimed to be functional towards drought resistance. During this period, the rate of reported new experimental transgenic model or crop plants for drought resistance has been increasing exponentially. Despite these numbers, qualified sources of information indicate a very limited impact on global dryland agriculture, whereas the genetically modified (GM) market hardly recognises drought-resistant GM cultivars. This paper discusses possible reasons for the limited impact of genomics on the delivery of drought-resistant cultivars, which are beyond issues of regulation, propriety or commercialisation. These reasons are mainly tied to scientific and methodological problems in drought stress gene expression work and the functional genomics protocols used to identify drought resistance. Insufficient phenotyping of experimental transgenic plants for drought resistance often does not allow true conclusions about the real function of the discovered genes towards drought resistance. The discussion is concluded by proposing an outline of a minimal set of tests that might help us resolve the real function of discovered genes, thus bringing the research results down to earth.

Pollen‐Mediated Gene Flow in Triticale

ABSTRACTTriticale (×Triticosecale Wittm. ex A. Camus) is primarily an animal feed crop with promising qualities for a bioindustrial crop. Development of genetically modified (GM) triticale is in progress and before release of GM cultivars, the potential for pollen‐mediated gene flow (PMGF) needs to be assessed to determine if it can coexist with conventional cultivars without causing market harm. Small and large plot experiments were conducted to quantify PMGF using an experimental blue aleurone triticale line as pollen donor and ‘AC Alta’ as pollen receptor. Small plot experiments were conducted at two locations in both 2007 and 2009 in Alberta, Canada. There were no site or year differences. Average PMGF from 0.2 to 1.4 m was 0.76%. Large plot experiments were conducted at two locations in both 2008 and 2009 using a concentric donor (20 by 20 m) and receptor (120 by 120 m) design. Over 17 million seeds were screened. There were no significant differences between sites or years. Pollen‐mediated gene flow best fit an exponential decay model in which the highest average PMGF (3.4%) occurred adjacent to the donor crop and rapidly declined to 0.09% by 50 m. Directional differences were detected with highest PMGF corresponding to prevailing wind directions at flowering. The estimated adventitious presence of GM triticale after harvest blending within a 50‐m conventional field was 0.22%. Pollen‐mediated gene flow in triticale is similar to spring wheat (Triticum aestivum L.) and should not prevent the coexistence of GM and conventional triticale using the 0.9% threshold established by the European Union.

Unintended polar metabolite profiling of carotenoid-biofortified transgenic rice reveals substantial equivalence to its non-transgenic counterpart

Substantial equivalence is a critical concept for biosafety assessment of genetically modified (GM) crops. To investigate substantial equivalence among carotenoid-biofortified GM rice and five conventional rice cultivars having common white (three) and red (two) grain colors, profiles of 52 polar metabolites were analyzed using gas chromatography time-of-flight mass spectrometry. The results were compared to evaluate the differences among GM and non-GM rice cultivars using principal components analysis. The GM rice is more comparable to its non-transgenic counterpart rice variety according to the closer co-separation than for other cultivars tested. This suggests that profiling of unintended polar metabolites could be a useful tool to reveal substantial equivalence of GM rice.

A 3-year study reveals that plant growth stage, season and field site affect soil fungal communities while cultivar and GM-trait have minor effects.

In this three year field study the impact of different potato (Solanum tuberosum L.) cultivars including a genetically modified (GM) amylopectin-accumulating potato line on rhizosphere fungal communities are investigated using molecular microbiological methods. The effects of growth stage of a plant, soil type and year on the rhizosphere fungi were included in this study. To compare the effects, one GM cultivar, the parental isoline, and four non-related cultivars were planted in the fields and analysed using T-RFLP on the basis of fungal phylum specific primers combined with multivariate statistical methods. Additionally, fungal biomass and some extracellular fungal enzymes (laccases, Mn-peroxidases and cellulases) were quantified in order to gain insight into the function of the fungal communities. Plant growth stage and year (and agricultural management) had the strongest effect on both diversity and function of the fungal communities while the GM-trait studied was the least explanatory factor. The impact of cultivar and soil type was intermediate. Occasional differences between cultivars, the amylopectin-accumulating potato line, and its parental variety were detected, but these differences were mostly transient in nature and detected either only in one soil, one growth stage or one year.

Quantitative detection of Potato virus Y in potato plants and aphids - Discussion of diverse applications in potato research

AbstractEvery year potato growers worldwide complain about severe yield losses caused by Potato virus Y (PVY). Therefore, PVY along with Potato virus Y belongs to the most important potato viruses. There are three main strains of PVY: PVY^O^, PVY^N^ and PVY^C^. However, also recombinant forms exist such as PVY^N^Wilga and PVY^NTN^, both of which increase in importance due to their potential to displace the non-recombinant strains at a high percentage. They appear also in mixed infections. In recent years PCR and qPCR assays were developed to differentiate PVY isolates. In order to identify PVY isolates by PCR often large amplicons have to be generated which requires the input of expensive enzymes. On the other hand, qPCR assays until now do not allow the differentiation between PVY^N^Wilga and PVY^NTN^.For the discrimination between PVY^O^/PVY^N^Wilga and PVY^N^/PVY^NTN^ a qPCR assay was developed, which allows the differentiation and highly efficient quantification of both strains and recombinants, respectively. For this purpose dual-labeled hydrolysis probes tagged with different fluorophores were designed. The assay is suitable for many different applications, for example safety research on genetically modified (GM) potato plants. The goal of this research is to determine whether genetic modification causes changes in resistance to viruses. Two different GM cultivars were examined for signs of altered resistance to an infection with PVY in comparison to their near-isogenic lines and three reference cultivars. Reference cultivars are included to determine the baselines for resistance and thus to be able to decide if the changes could represent a biological risk. The plants to be investigated were mechanically inoculated with PVY^N^Wilga or PVY^NTN^ and analyzed by means of the developed assay after two weeks. The results of the experiment indicate that the differences in virus titer between the reference cultivars are higher than between the GM potatoes and their isogenic lines. Therefore, in our experiments the GM potato plants showed no alteration in PVY resistance to neither one of the tested strains.Since Myzus persicae is one of the most important vectors transmitting PVY, the developed assay will also be applied to the quantification of PVY particles in aphids. The displacement of PVY^O^ and PVY^N^ by PVY^N^Wilga and PVY^NTN^ may be due to a difference in efficiency of transmission by M. persicae. Therefore, the objective is to test whether more virus particles of the recombinant forms in comparison to the non-recombinant strains PVY^O^ and PVY^N^ bind in the stylets of M. persicae. A third possible application of the developed assay may be of interest in potato breeding. The exact quantification of PVY particles in plants allows the classification of resistance in potato plants. It is possible to estimate whether a resistance is extreme or not. Extreme resistance is characterized by the absence or presence of very low amounts of virus particles in plants several days after inoculation. When testing the plants for PVY infection by ELISA, often unspecific reactions occur which makes it difficult to differentiate between plants weakly infected and plants very weakly infected. An exact quantification of the PVY titer gives more certainty for the determination of the resistance type.In conclusion, the developed assay is an efficient and low-cost method that allows the differentiation and quantification of PVY^O^/PVY^N^Wilga on the one hand and PVY^N^/PVY^NTN^ on the other hand with high throughput. The method can be utilized for a wide range of applications in potato research.

Quantitative detection of Potato virus Y in potato plants and aphids – Discussion of diverse applications in potato research

Every year potato growers worldwide complain about severe yield losses caused by Potato virus Y (PVY). Therefore, PVY along with Potato virus Y belongs to the most important potato viruses. There are three main strains of PVY: PVY^O^, PVY^N^ and PVY^C^. However, also recombinant forms exist such as PVY^N^Wilga and PVY^NTN^, both of which increase in importance due to their potential to displace the non-recombinant strains at a high percentage. They appear also in mixed infections. In recent years PCR and qPCR assays were developed to differentiate PVY isolates. In order to identify PVY isolates by PCR often large amplicons have to be generated which requires the input of expensive enzymes. On the other hand, qPCR assays until now do not allow the differentiation between PVY^N^Wilga and PVY^NTN^.For the discrimination between PVY^O^/PVY^N^Wilga and PVY^N^/PVY^NTN^ a qPCR assay was developed, which allows the differentiation and highly efficient quantification of both strains and recombinants, respectively. For this purpose dual-labeled hydrolysis probes tagged with different fluorophores were designed. The assay is suitable for many different applications, for example safety research on genetically modified (GM) potato plants. The goal of this research is to determine whether genetic modification causes changes in resistance to viruses. Two different GM cultivars were examined for signs of altered resistance to an infection with PVY in comparison to their near-isogenic lines and three reference cultivars. Reference cultivars are included to determine the baselines for resistance and thus to be able to decide if the changes could represent a biological risk. The plants to be investigated were mechanically inoculated with PVY^N^Wilga or PVY^NTN^ and analyzed by means of the developed assay after two weeks. The results of the experiment indicate that the differences in virus titer between the reference cultivars are higher than between the GM potatoes and their isogenic lines. Therefore, in our experiments the GM potato plants showed no alteration in PVY resistance to neither one of the tested strains.Since Myzus persicae is one of the most important vectors transmitting PVY, the developed assay will also be applied to the quantification of PVY particles in aphids. The displacement of PVY^O^ and PVY^N^ by PVY^N^Wilga and PVY^NTN^ may be due to a difference in efficiency of transmission by M. persicae. Therefore, the objective is to test whether more virus particles of the recombinant forms in comparison to the non-recombinant strains PVY^O^ and PVY^N^ bind in the stylets of M. persicae. A third possible application of the developed assay may be of interest in potato breeding. The exact quantification of PVY particles in plants allows the classification of resistance in potato plants. It is possible to estimate whether a resistance is extreme or not. Extreme resistance is characterized by the absence or presence of very low amounts of virus particles in plants several days after inoculation. When testing the plants for PVY infection by ELISA, often unspecific reactions occur which makes it difficult to differentiate between plants weakly infected and plants very weakly infected. An exact quantification of the PVY titer gives more certainty for the determination of the resistance type.In conclusion, the developed assay is an efficient and low-cost method that allows the differentiation and quantification of PVY^O^/PVY^N^Wilga on the one hand and PVY^N^/PVY^NTN^ on the other hand with high throughput. The method can be utilized for a wide range of applications in potato research.

Sugarcane (Saccharum X officinarum): A Reference Study for the Regulation of Genetically Modified Cultivars in Brazil

Global interest in sugarcane has increased significantly in recent years due to its economic impact on sustainable energy production. Sugarcane breeding and better agronomic practices have contributed to a huge increase in sugarcane yield in the last 30 years. Additional increases in sugarcane yield are expected to result from the use of biotechnology tools in the near future. Genetically modified (GM) sugarcane that incorporates genes to increase resistance to biotic and abiotic stresses could play a major role in achieving this goal. However, to bring GM sugarcane to the market, it is necessary to follow a regulatory process that will evaluate the environmental and health impacts of this crop. The regulatory review process is usually accomplished through a comparison of the biology and composition of the GM cultivar and a non-GM counterpart. This review intends to provide information on non-GM sugarcane biology, genetics, breeding, agronomic management, processing, products and byproducts, as well as the current technologies used to develop GM sugarcane, with the aim of assisting regulators in the decision-making process regarding the commercial release of GM sugarcane cultivars.

Comparisons of Genetically Modified and Non‐Genetically Modified Soybean Cultivars and Weed Management Systems

Adoption of glyphosate‐resistant crops and the use of glyphosate has resulted in the evolution of glyphosate‐resistant weeds. The objective of the studies reported was to investigate yield and weed management systems of genetically modified (GM) and non‐GM soybean [Glycine max (L.) Merr.] at three Iowa locations during 2007 and 2008. Yield of glyphosate‐resistant, glufosinate‐resistant, and non‐GM cultivars was determined in six site–years. The non‐GM cultivars yielded 315 and 265 kg ha−1 less than the glyphosate‐resistant and glufosinate‐resistant cultivars, respectively, while no differences between GM cultivars were observed. Weed management systems differed for the cultivars but had equivalent weed control (>90%). Weed management systems in the non‐GM cultivars caused more phytotoxicity (36% versus approximately 5% 7 d after application) and, coincidentally, the non‐GM cultivars had the lowest yields. No differences in phytotoxicity were observed among the weed management systems for the GM cultivars. Similarly, no differences in yield were observed comparing the weed management systems for the GM cultivars. The experiment locations did not have high weed population densities although the untreated controls yielded 48% less than the other weed management systems included in the studies. Given concerns for glyphosate‐resistant weeds, the studies demonstrated that acceptable and equivalent options to glyphosate‐resistant soybean exist to manage glyphosate‐resistant weeds in maturity groups 2 and 3 soybean which represent the majority of the U.S. soybean production.