Present Development Situation of Transgenic Crops and Effect on Ecological Environment

The present development situation of transgenic crops and their effect on ecological environment are introduced in the paper. Some relevant strategies for their future and how to control the risks of ecological environment are presented.

Improved method for nondestructive measurement of dynamic pollen source strength from transgenic crops using sonic anemometer

Pollen-mediated gene flow from transgenic crops is a concern of the scientific community as well as the general public.Current lack is a nondestructive method to measure dynamic(hourly or shorter time period)source pollen release rate(source strength)from these crops.This paper reports an improved method using Rotorod concentration samplers and sticky slides,together with a fast response sonic anemometer,for measuring source strength from transgenic corn crops.Field measurements were made during the pollination season of 2001 at the Agronomy Research Farm,University of Connecticut,Storrs,Connecticut.Data were analyzed and used to estimate the pollen source strength of the corn crops at hourly time steps by considering both atmospheric transport and gravitational deposition processes.Details of the calculation and assumptions of the method are provided.Results from this study demonstrate that this method is sufficiently robust for use in estimating pollen source strength of transgenic crops with heavy pollen grains in assessing gene flow risks associated with field production of transgenic crops.

Transgenic Crops by Direct Treatment of Exogenous DNA without Agrobacterium tumefaciens Plasmid and Tissue Culture

Gene transfer methods are developing quickly recently, but each method has its limitations. We introduce a new gene transfer technique in this paper, which is simple, effective, and easy to operate,but does not get enough attention from scientists. This technique is used to transform plants by in jecting exogenous DNA to stigma, style, ovary, young fruit or meristem of the recipient, or soaking the recipient's seeds in exogenous DNA solution. Lots of heritable variations were found in many characters of many crops. It may be used to create new germplasms or realize gene exchange between different species, genera, or families, even between animals and plants. A brief discussion was given to the mechanism of exogenous DNA introduction, integration into and expression in the recipient. We also discussed the merits and limitations of the technique.Currently there are two successful approaches that can be used to transform paints genetically,but each method has its limitations that are delaying the application of the techniques to certain commercially important crops. The first technique exploits a natural genetic engineer, Agrobacterium tumefaciens, which contains a tumor-inducing (Ti) plasmid that transfers a DNA segment (the T-DNA) from the plasmid to the nuclear genome of infected plants (or in vitro to plant tissue). The method is restricted to dicotyledenous plants; monocotyledenous plants are usually not susceptible to agrobacterial infection. The second technique involves direct transfer of DNA to plant protoplast, prepared by enzymatic digestion of cell walls, for example by chemically stimulated uptake using polyethylene glycol or a high voltage pulse, generating transient 'holes' in the protoplast membrane. This technique depends on a tissue culture system that allows regeneration of mature plants from protoplasts. But so far it is impossible to achieve plant regeneration from protoplasts in many crops. Both techniques use dominant selectable markers (for example, kanamycin resistance) to select for the transformed tissue or plant which can then be screened for expression of co-transferred but unselected genes (Lichenstein, 1987).Now there is a new successful method which can transform various crops, regardless of dicots or monocots, cereals or legumes. It doesn't need Agrobacterium tumefaciens and plasmid, doesn't depend on the tissue culture system that allows regeneration of mature plants from protoplasts.Comple and advance equipments are not necessary. It is very simple, but very effective. Next is a review about the technique, its application in several crops, the mechanism of transformation, and its merits and limitations.

Construction of Transgenic Crop Germplasm Effective Function and Characteristic Analysis

Germplasm effect reflects the quantitative relation between production ability of germplasm elements and yield （quality） of a certain crop, which can be shown by mathematic function, namely, germplasm effect function. Germplasm effect of a crop variety is an aggregation of many effective factors, and is restrained by different effective factors; constant increase of any one effect of germplasm elements would lead to law of effect decline, therefore, possible modes of transgenic crops effect function were deduced according to the law of effect decline. The possible modes of single transgenic germplasm effect function and multi-transgenic germplasm effect regression equation were discussed, and the characteristics of germplasm effect regression equation were analyzed in this paper.

Plant Breeding for Harmony between Modern Agriculture Production and the Environment

The world population is estimated to be 9.2 billion in 2050. To sufficiently feed these people, the total food production will have to increase 60% - 70%. Climate models predict that warmer tem-peratures and increases in the frequency and duration of drought during the present century will have negative impact on agricultural productivity. These new global challenges require a more complex integrated agricultural and breeding agenda that focuses on livelihood improvement coupled with agro-ecosystem resilience, eco-efficiency and sustainability rather than just on crop productivity gains. Intensifying sustainability agro-ecosystems by producing more food with lower inputs, adapting agriculture to climate change, conserving agro-biodiversity through its use, and making markets to work for the small farmers are needed to address the main issues of our time. Plant breeding has played a vital role in the successful development of modern agriculture. Development of new cultivars will be required while reducing the impact of agriculture on the environment and maintaining sufficient production. Conventional plant breeding will remain the backbone of crop improvement strategies. Genetic engineering has the potential to address some of the most challenging biotic constraints faced by farmers, which are not easily addressed through conventional plant breeding alone. Protective measures and laws, especially patenting, must be moderated to eliminate coverage so broad that it stifles innovation. They must be made less restrictive to encourage research and free flow of materials and information. Small farmers have an important role in conserving and using crop biodiversity. Public sector breeding must remain vigorous, especially in areas where the private sector does not function. This will often require benevolent public/private partnerships as well as government support. Active and positive connections between the private and public breeding sectors and large-scale gene banks are required to avoid a possible conflict involving breeders’ rights, gene preservation and erosion. Plant breeding can be a powerful tool to bring “harmony” between agriculture and the environment, but partnerships and cooperation are needed to make this a reality.

Assessment of the potential toxicity of insecticidal compounds to Peristenus spretus,a parasitoid of mirid bugs

With the increased cultivation of Bt crops in China,Apolygus lucorum and other mirid bugs have emerged as important agricultural pests because they are insensitive to the Bt proteins.In addition,the reduction of pesticide applications after planting Bt crops also increases the severity of mirid bug outbreaks.Peristenus spretus is a parasitoid of mirid nymphs,but its sensitivity to Bt proteins is not known.In the current study,we developed a dietary exposure assay to assess the effects of Bt proteins(Cry1Ab,Cry1Ac,Cry1F,Cry2Aa,and Cry2Ab)on P.spretus adults using a diet consisting of a 10% honey solution with or without Bt proteins at 400μg g^(-1) diet.The results showed that the survival and reproduction of P.spretus adults were reduced by the cysteine protease inhibitor E-64(a positive control)but were not affected by any of the five Bt proteins.The activities of digestive,detoxifying,and antioxidant enzymes in P.spretus were also unaffected by diets containing the Cry proteins,but they were significantly affected by the diet containing E-64.We then developed a tritrophic bioassay to determine the effects of the five Bt proteins on P.spretus larvae and pupae.In this assay,A.lucorum nymphs fed an artificial diet containing Cry proteins were used as the hosts for P.spretus.The results of the tri-trophic assay indicated that neither the pupation rate nor the eclosion rate of the P.spretus parasitoids were significantly affected by the presence of high concentrations of Bt proteins in the parasitized A.lucorum nymphs.The overall results indicate that these two assays can be used to evaluate the toxicity of insecticidal compounds to P.spretus and that the tested Cry proteins are not toxic to P.spretus.

Development and application of plant transformation techniques

Genetic transformation is a powerful biotechnology for introducing novel genes into economically important plants from distantly-related plants or even unrelated species such as microbes and animals.This feat is impossible to be achieved by conventional breeding techniques.Development of transgenic plants has been a controversial subject since 1971 when the first genetically modified organism（GMO）was developed（James and Krattiger1996）.

Effects of elevated CO2 on the interspecific competition between two sympatric species of Aphis gossypii and Bemisia tabaci fed on transgenic Bt cotton

Effects of elevated CO2 （twice ambient vs. ambient） and Bt CrylAc transgene （Bt cotton cv. 33B vs. its nontransgenic parental line cv. DP5415） on the interspecific competition between two ecologically similar species of cotton aphid Aphis gossypii and whitefly biotype-Q Bemisia tabaci were studied in open-top chambers. The results indicated that elevated CO2 and Bt cotton both affected the population abundances of A. gossypii and biotype-Q B. tabaci when introduced solely （i.e., without interspecific competition） or two species coexisted （i.e., with interspecific competition）. Compared with ambient CO2, elevated COe increased the population abundances ofA. gossypii and biotype-Q B. tabaci as fed on Bt and nontransgenic cotton on 45 （i.e., seedling stage） and 60 （i.e., flowering stage） days after planting （DAP）, but only significantly enhanced aphid abundance without interspecific competition on the 45-DAP nontransgenic cotton and 60-DAP Bt cotton, and significantly increased whitefly abundance with interspecific competition on the 45-DAP Bt cotton and 60-DAP nontransgenic cotton. In addition, compared with nontransgenic cotton at elevated CO2, Bt cotton significantly reduced biotype-Q B. tabaci abundances without and with interspecific competition during seedling and flowering stage, while only significantly decreasing A. gossypii abundances without interspecific competition during the seedling stage. When the two insect species coexisted, the proportions ofbiotype-Q B. tabaci were significantly higher than those ofA. gossypii on Bt and nontransgenic cotton at the same CO2 levels, and elevated CO2 only significantly increased the percentages of biotype-Q B. tabaci and significantly reduced the proportions of A. gossypii on seedling and flowering nontransgenic cotton. Therefore, the effects of elevated CO2 were favorable for biotype-Q B. tabaci to out-compete A. gossypii under the predicted global climate change.

Evaluation of potential RNA-interference-target genes to control cotton mealybug, Phenacoccus solenopsis （Hemiptera： Pseudococcuidae）

RNA interference （RNAi） of vital insect genes is a potential tool for targeted pest control. However, selection of the right target genes is a challenge because the RNAi efficacy is known to vary among insect species. Cotton mealybug, Phenacoccus solenopsis, is a phloem-feeding economically important crop pest. We evaluated the RNAi of 2 vital genes, Bursicon （PsBur） and V-ATPase （Ps V-ATPase） as potential targets in P. solenopsis for its control. PCR fragments of PsBur and PsV-ATPase were amplified using cDNA synthesized from the total RNA. The PCR amplicons were cloned into Potato virus X （PVX） to develop recombinant PVX for the inoculation ofNicotiana tabacum plants for bioassays with healthy P. solenopsis. Reverse-transcription-polymerase chain reaction （RT- PCR） was used to validate the expression oftransgenes in the recombinant-PVX-inoculated plants （treated）, and suppression of the target genes in the mealybugs exposed to them. The RT-PCR confirmed the expression of transgenes in the treated plants. Mealybug individuals on treated plants either died or showed physical deformities. Further, the population of mealybug was significantly reduced by feeding on N. tabacum expressing RNAi triggers against PsBur and Ps V-A TPase. The results conclude that RNAi is activated in P. solenopsis by feeding on N. tabacum expressing RNAi triggering elements of PsBur and Ps V-ATPase genes through recombinant PVX vector. Further, V-ATPase and Bursicon genes are potential targets for RNAi-mediated control ofP. solenopsis.

Susceptibility of field populations of sugarcane borer from non-Bt and Bt maize plants to five individual Cry toxins

Sugarcane borer, Diatraea saccharalis （E）, is a major target of transgenic maize expressing Bacillus thuringiensis （Bt） proteins in South America and the US mid- south region. Resistance development in target pest populations is a major threat to the sustainable use of Bt crops. In our field trials in 2009, a significant number of live borers and plant injury fi＇om D. saccharalis were observed in an experimental SmartStaxTM maize line. The objective of this study was to assess the relative susceptibility of two field popula- tions ofD. saccharalis collected from non-Bt and Bt maize plants containing SmartStaxTM traits to five individual Cry proteins. The five Bt proteins included two proteins （Cry 1A. 105 and Cry2Ab2） that were expressed in SmartStaxTM maize plants and three other common Bt proteins （Cry 1Aa, Cry 1Ab and Cry l Ac） that were not produced in SmartStaxTM. Larval mortality and growth inhibition on Bt diet of the fourth generation after field collections were evaluated 7 days after release of neonates on the diet surface. The laboratory bioassays showed that 50% lethal concentration （LCs0） values for CrylA. 105 and Cry2Ab2 for the population originated from Bt plants were 3.55- and 1.34-fold greater, respectively, than those of the population collected from non-Bt plants. In contrast, relative to the popula- tion from non-Bt plants, the LCs0 of the population sampled from Bt plants were 3.85-, 2.5- and 1.64-fold more sensitive to CrylAa, CrylAb and CrylAc, respectively. The re- sults did not provide clear evidence to conclude that the observed field survival of D. saccharalis on Bt plants was associated with increased levels of resistance.

Monarchs in decline： a collateral landscape-level effect of modern agriculture

We review the postulated threatening processes that may have affected the de- cline in the eastern population of the monarch butterfly, Danausplexippus L. （Lepidoptera： Nymphalidae）, in North America. Although there are likely multiple contributing factors, such as climate and resource-related effects on breeding, migrating, and overwintering populations, the key landscape-level change appears to be associated with the widespread use of genetically modified herbicide resistant crops that have rapidly come to dominate the extensive core summer breeding range. We dismiss misinterpretations of the apparent lack of population change in summer adult count data as logically flawed. Glyphosate-tolerant soybean and maize have enabled the extensive use of this herbicide, generating widespread losses of milkweed （Asclepias spp.）, the only host plants for monarch larvae. Modeling studies that simulate lifetime realized fecundity at a landscape scale, direct counts of milkweeds, and extensive citizen science data across the breeding range suggest that a herbicide-induced, landscape-level reduction in milkweed has precipitated the decline in monarchs. A recovery will likely require a monumental effort for the re-establishment of milkweed resources at a commensurate landscape scale.

Potential impact of genetically modified Lepidoptera-resistant Brassica napus in biodiversity hotspots： Sicily as a theoretical model

The general increase of the cultivation and trade of Bt transgenic plants resis- tant to Lepidoptera pests raises concerns regarding the conservation of animal and plant biodiversity. Demand for biofuels has increased the cultivation and importation of oilseed rape （Brassica napus L.）, including transgenic lines. In environmental risk assessments （ERAs） for its potential future cultivation as well as for food and feed uses, the impact on wild Brassicaeae relatives and on non-target Lepidoptera should be assessed. Here we consider the potential exposure of butterflies as results of possible cultivation or natural- ization of spilled seed in Sicily （Italy）. Diurnal Lepidoptera, which are pollinators, can be exposed directly to the insecticidal proteins as larvae （mainly of Pieridae） through the host and through the pollen that can deposit on other host plants. Adults can be exposed via pollen and nectar. The flight periods of butterflies were recorded, and they were found to overlap for about 90% of the flowering period ofB. napus for the majority of the species. In addition, B. napus has a high potential to hybridise with endemic taxa belonging to the B. oleracea group. This could lead to an exposure of non-target Lepidoptera if introgression of the Bt gene into a wild population happens. A rank of the risk for butterflies and wild relatives of oilseed rape is given. We conclude that, in environmental risk assessments, attention should be paid to plant-insect interaction especially in a biodiversity hotspot such as Sicily.

Current development and application of soybean genomics

Soybean (Glycine max), an important domesticated species originated in China, constitutes a major source ofedible oils and high-quality plant proteins worldwide. In spite of its complex genome as a consequence of an ancienttetraploidilization, platforms for map-based genomics, sequence-based genomics, comparative genomics and functionalgenomics have been well developed in the last decade, thus rich repertoires of genomic tools and resources are available,which have been influencing the soybean genetic improvement. Here we mainly review the progresses of soybean(including its wild relative Glycine soja) genomics and its impetus for soybean breeding, and raise the major biologicalquestions needing to be addressed. Genetic maps, physical maps, QTL and EST mapping have been so well achievedthat the marker assisted selection and positional cloning in soybean is feasible and even routine. Whole genomesequencing and transcriptomic analyses provide a large collection of molecular markers and predicted genes, which areinstrumental to comparative genomics and functional genomics. Comparative genomics has started to reveal theevolution of soybean genome and the molecular basis of soybean domestication process. Microarrays resources,mutagenesis and efficient transformation systems become essential components of soybean functional genomics.Furthermore, phenotypic functional genomics via both forward and reverse genetic approaches has inferred functionsof many genes involved in plant and seed development, in response to abiotic stresses, functioning in plant-pathogenicmicrobe interactions, and controlling the oil and protein content of seed. These achievements have paved the way forgeneration of transgenic or genetically modified (GM) soybean crops.