Non-transgenic Cotton Research Articles

Effect of NaCl-stressed Bacillus thuringiensis (Bt) cotton on the feeding behaviors and nutritional parameters of Helicoverpa armigera.

Saline-alkali soil is an arable land resource on which transgenic Bacillus thuringiensis (Bt) cotton has been planted on a large scale in accordance with food security strategies. There are, however, concerns about the insecticidal effects of Bt cotton on target insect pests. In this study, a Bt cotton variety, GK19, and its nontransgenic parent variety, Simian-3, were used as experimental models for investigating the effect of the expression of exogenous insecticidal proteins in Bt cotton under NaCl stress on the feeding behavior and nutritional parameters of Helicoverpa armigera. The results showed that the expression of exogenous insecticidal proteins in GK19 was significantly inhibited under NaCl stress. However, the feeding, crawling, resting and spinning down behavior of the 5th instar H. armigera larvae on GK19 Bt cotton, as well as the amount of food consumed and feces produced by these larvae, did not markedly differ under different NaCl concentrations. In contrast, the mean relative growth rate (MRGR), relative growth rate (RGR), approximate digestibility (AD), efficiency of conversion of ingested food (ECI) and efficiency of conversion of digested food (ECD) of the larvae markedly decreased in response to NaCl stress. Under the same concentration of NaCl, the nutritional parameters of the bollworm larvae on GK19 Bt cotton or Simian-3 nontransgenic cotton were different. However, the interaction between salt stress and cotton variety had no significant effect on the feeding behavior or nutritional parameters of H. armigera larvae. These results may provide a scientific basis for determining the effect of exogenous insecticidal protein expression in Bt cotton under NaCl stress on H. armigera and can therefore be useful for the effective application of Bt cotton in saline-alkali soils to prevent and control H. armigera.

A new observation on feeding behaviour of pink bollworm and its application in screening Bt-resistant population.

The pink bollworm (PBW), Pectinophora gossypiella (Saund.) does not feed on leaves in natural circumstances. We made an attempt with the first instar larva (5days old) and found it eats the leaf in the absence of other foods. Utilizing this new feeding behaviour, a simple methodology was developed for screening of resistance in PBW against Bt cotton plants. The PBW collected from BGII Bt cotton fields (BGII-resistant population) and NBAIR culture (susceptible population) were reared under laboratory conditions for two generations. Laboratory reared 5-day old larvae of PBW were released on cotton leaf discs individually for screening. The BGII-resistant and susceptible larvae fed an average leaf area of 75.52 ± 16.68 and 5.95 ± 0.93 mm2 with survival rate of 90 and 4% respectively, in BGII Bt cotton leaves. Whereas in case of non-Bt cotton (MCU13), the BGII-resistant and susceptible larvae consumed average leaf area of 114.84 ± 23.70 and 116.80 ± 24.14 mm2 with survival rate of 93.34 and 95.33%, respectively. In addition to the screening process, the larval survivors were transferred to an artificial diet after 7days of experiment and observed up to their emergence as adults. To confirm the development of resistance in PBW, sequencing of larval DNA amplicons was carried out and it revealed mutation in the cadherin gene of the BGII-resistant PBW population. Hence, the detached leaf bit feeding assay described here could be used in a simple manner for screening of resistance developed by PBW against Bt cotton and also for evaluating Bt cotton plants for their inherent resistance to PBW. This method could also be used for studying toxicity of Bt isolates by coating spore-crystal mixture on non-transgenic cotton leaf discs.

Performance of the Natural Mortality Factors of Aphis gossypii (Hemiptera: Aphididae) as a Function of Cotton Plant Variety and Phenology.

Natural mortality factors are responsible for regulating pest populations in the field. However, plant attributes such as the variety and phenological stage can influence the performance of these factors. Therefore, we investigated the performance of the natural mortality factors of Aphis gossypii (Glover; Hemiptera: Aphididae) as a function of the plant variety and phenology. To investigate the performance of these factors, we evaluated the mortality of A. gossypii caused by natural mortality factors for 2 yr in field conditions in transgenic (Bacillus thuringiensis/Roundup Ready) and non-transgenic cotton crops during vegetative, flowering, and fruiting stages. The natural mortality factors were affected similarly between the transgenic and non-transgenic plants; however, differences were observed in their performance, depending on the phenological stage of the cotton plant. Compared with other stages, predation was higher in the flowering stage, whereas the mortality caused by rainfall was higher in the vegetative stage. Coccinellid beetles were primarily responsible for the predation on A. gossypii. These findings highlight that the performance of the natural mortality factors of A. gossypii varied more as a function of the phenological stage of cotton than of the variety.

Persistence of Cry1Ac Protein from Transgenic Bt Cotton Cultivation and Residue Returning in Fields and Its Effect on Functional Diversity of Soil Microbial Communities

The persistence of Cry1Ac protein in the soil and its effect on soil microbial communities are a core issue in assessing the ecological risk of transgenic Bacillus thuringiensis (Bt) cotton. In this study a field experiment was conducted on the cultivation of transgenic Bt cotton (Jin 26 and BtJi 668) with the immediate returning of residues to the fields, in order to quantify the Cry1Ac protein content in the fields and investigate its effects on the functional diversity of soil microbial communities. Cry1Ac protein in the residue-soil mixture was gradually degraded in the transgenic Bt cotton fields. After transgenic Bt cotton straw was returned to the fields for 30 d, 63.73% and 58.33% of the initial amounts of Cry1Ac protein were degraded in the Jin 26 and BtJi 668 fields, respectively. Before the crops were sown in the following year (180 d after returning the straw), no Cry1Ac protein was detected in the fields. After returning the cotton straw to the fields for 30 d, the Shannon-Wiener and McIntosh indices of soil microbial communities in the transgenic Bt cotton fields were significantly higher than those in the non-transgenic cotton fields. Meanwhile, the utilization of carbon sources including amino acids, amines, and carbohydrates by the soil microbial communities significantly increased. Both the McIntosh index and the utilization of carbohydrates increased until 180 d. Principal component analysis revealed that amino acids, amides, and carbohydrates were the main carbon sources distinguishing the two principal component factors. These findings indicated that Cry1Ac protein did not accumulate in the fields after transgenic Bt cotton was planted for one year and the residues were immediately returned to the fields; however, the original functional diversity of soil microbial communities was affected continuously.

Effects of soil salinity on rhizosphere soil microbes in transgenic Bt cotton fields

With increased cultivation of transgenic Bacillus thuringiensis (Bt) cotton in the saline alkaline soil of China, assessments of transgenic crop biosafety have focused on the effects of soil salinity on rhizosphere microbes and Bt protein residues. In 2013 and 2014, investigations were conducted on the rhizosphere microbial biomass, soil enzyme activities and Bt protein contents of the soil under transgenic Bt cotton (variety GK19) and its parental non-transgenic cotton (Simian 3) cultivated at various salinity levels (1.15, 6.00 and 11.46 dS m−1). Under soil salinity stress, trace amounts of Bt proteins were observed in the Bt cotton GK19 rhizosphere soil, although the protein content increased with cotton growth and increased soil salinity levels. The populations of slight halophilic bacteria, phosphate solubilizing bacteria, ammonifying bacteria, nitrifying bacteria and denitrifying bacteria decreased with increased soil salinity in the Bt and non-Bt cotton rhizosphere soil, and the microbial biomass carbon, microbial respiration and soil catalase, urease and alkaline phosphatase activity also decreased. Correlation analyses showed that the increased Bt protein content in the Bt cotton rhizosphere soil may have been caused by the slower decomposition of soil microorganisms, which suggests that salinity was the main factor influencing the relevant activities of the soil microorganisms and indicates that Bt proteins had no clear adverse effects on the soil microorganisms. The results of this study may provide a theoretical basis for risk assessments of genetically modified cotton in saline alkaline soil.

English

Introduction of multiple traits in crop plants for desirable character is an essential tool of Biotechnological application. To overcome problem of insect pests and weeds cotton variety FBS-37 was genetically modified by transformation of CEMB Cry1Ac+Cry2A and GTGene cloned in different plant expression vectors under CaMV35S Promoter and nopaline synthase Nos Terminator. CEMB optimized protocol of cotton gene transformation i.e. Agrobacterium mediated shoot apex cut method was applied for transformation of these genes constructs in cotton. Overall transformation efficiency was found to be 1.05%. Putative transgenic cotton plants were shifted to soil pots and acclimatized in the green house conditions. PCR with gene specific primers amplified 190bp for EPSPS (Glyphosate GTG) and 1000bp for each of Cry1Ac and Cry2A. Quantification of Cry1Ac, Cry2A and GTG protein through ELISA determined maximum of 0.8 µ g/g, 1 µ g/g and 0.9 µ g/g of tissue respectively. 100% mortality was obtained in 2 nd instar larvae of Heliothus armigera when compared with non-transgenic control cotton plants where maximum damaged was seen in leaf bioassay. Moreover, transgenic cotton plants successfully survived when sprayed with 1600ml/acre of glyphosate as compared to control where 100% mortality and necrosis occur after 7 days of spray assay in control conditions. Keyword: Herbicide resistant, glyphosate, Cry1Ac, GTG, weedicide resistant

Overexpression of ScALDH21 gene in cotton improves drought tolerance and growth in greenhouse and field conditions

Aldehyde dehydrogenase (ALDH) is essential for scavenging redundant aldehydes when plants are exposed to stress. The aim of the present study was to validate the ectopic expression of the ScALDH21 gene, which is isolated from Syntrichia caninervis, an extremely drought-tolerant moss, to improve drought tolerance in cotton (Gossypium hirsutum L.). In our study, the ScALDH21-transformed cotton was identified via PCR, RT-PCR, and DNA gel blotting, and the growth and physiological characteristics related to drought tolerance were compared between the transgenic cotton (TC) and non-transgenic cotton (NT) grown in a greenhouse and in field conditions. The results indicated that TC accumulated approximately 11.8–304 % more proline than did NT under drought stress, and produced a lower concentration of lipid peroxidation-derived reactive aldehydes and had a higher peroxidase activity under oxidative stress. Moreover, TC showed reduced loss of the net photosynthetic rate compared with NT. Under field conditions, TC showed greater plant height, larger bolls, and greater cotton fiber yield than NT, but no significant difference in fiber quality between TC and NT following different water-withholding treatments. These results suggest that overexpression of ScALDH21 can greatly improve the drought tolerance of cotton without reduction in yield and fiber quality.

The Effects of Fe2O3 Nanoparticles on Physiology and Insecticide Activity in Non-Transgenic and Bt-Transgenic Cotton.

As the demands for nanotechnology and nanoparticle (NP) applications in agriculture increase, the ecological risk has drawn more attention because of the unpredictable results of interactions between NPs and transgenic crops. In this study, we investigated the effects of various concentrations of Fe2O3 NPs on Bt-transgenic cotton in comparison with conventional cotton for 10 days. Each treatment was conducted in triplicate, and each experiment was repeated three times. Results demonstrated that Fe2O3 NPs inhibited the plant height and root length of Bt-transgenic cotton and promoted root hairs and biomass of non-transgenic cotton. Nutrients such as Na and K in Bt-transgenic cotton roots increased, while Zn contents decreased with Fe2O3 NPs. Most hormones in the roots of Bt-transgenic cotton increased at low Fe2O3 NP exposure (100 mg⋅L-1) but decreased at high concentrations of Fe2O3 NPs (1000 mg⋅L-1). Fe2O3 NPs increased the Bt-toxin in leaves and roots of Bt-transgenic cotton. Fe2O3 NPs were absorbed into roots, then transported to the shoots of both Bt-transgenic and non-transgenic cottons. The bioaccumulation of Fe2O3 NPs in plants might be a potential risk for agricultural crops and affect the environment and human health.

2009—2013年Bt棉田节肢动物群落多样性动态变化

PDF HTML阅读 XML下载 导出引用 引用提醒 2009-2013年Bt棉田节肢动物群落多样性动态变化 DOI: 10.5846/stxb201411112228 作者: 作者单位: 中国农业科学院棉花研究所/棉花生物学国家重点实验室,中国农业科学院棉花研究所/棉花生物学国家重点实验室,中国农业科学院棉花研究所/棉花生物学国家重点实验室,中国农业科学院棉花研究所/棉花生物学国家重点实验室,中国农业科学院棉花研究所/棉花生物学国家重点实验室,中国农业科学院棉花研究所/棉花生物学国家重点实验室,中国农业科学院棉花研究所/棉花生物学国家重点实验室 作者简介: 通讯作者: 中图分类号: 基金项目: 转基因重大专项资助项目（2014ZX08011-002） Dynamic changes in the biodiversity of arthropod communities in transgenic Bt cotton fields between 2009 and 2013 Author: Affiliation: Institute of Cotton Research of CAAS/State Key Laboratory of Cotton Biology,Anyang,Institute of Cotton Research of CAAS/State Key Laboratory of Cotton Biology,Anyang,Institute of Cotton Research of CAAS/State Key Laboratory of Cotton Biology,Anyang,Institute of Cotton Research of CAAS/State Key Laboratory of Cotton Biology,Anyang,Institute of Cotton Research of CAAS/State Key Laboratory of Cotton Biology,Anyang,Institute of Cotton Research of CAAS/State Key Laboratory of Cotton Biology,Anyang,Institute of Cotton Research of CAAS/State Key Laboratory of Cotton Biology,Anyang Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:研究多年种植转Bt基因棉花对棉田节肢动物群落昆虫结构与组成、生物多样性的影响，明确其变化趋势，可为棉田害虫综合治理与生态调控、转Bt基因棉花环境安全性评价提供科学借鉴。于2009-2013年连续5年对转Bt基因棉花中棉所41和非转基因棉花中棉所49棉田节肢动物群落进行了系统调查，并结合5a气象因子的变化，分析了5年内棉田节肢动物群落相关参数的变化趋势。结果分析表明，2009-2013年中棉所41棉田昆虫群落、害虫亚群落和天敌亚群落所属目数有所上升，但差异不显著；所属科数、物种数、个体总数均呈现先上升后下降的趋势，个别年份差异显著，其余年份基本保持不显著的波动水平；昆虫群落和害虫亚群落多样性指数呈下降的趋势，至2013年下降达到显著水平，其余年份之间差异不显著，天敌亚群落多样性指数无显著变化；昆虫群落、害虫亚群落和天敌亚群落均匀性指数无显著变化；昆虫群落和害虫亚群落优势集中性指数有所上升，至2013年差异达到显著水平，天敌亚群落优势集中性各年份间无显著变化；与中棉所49棉田相比，相同年份中棉所41棉田昆虫群落、害虫亚群落和天敌亚群落结构与组成、多样性指数、均匀性指数和优势集中性指数均无显著差异。可见，短期内非剧烈天气变化对转基因棉田节肢动物群落、害虫亚群落和天敌亚群落在结构与组成、生物多样性方面没有明显的影响。 Abstract:In this study, effects of transgenic Bt cotton on the structure, composition, and biodiversity of arthropod communities were systematically investigated in cotton fields over five consecutive years, from 2009 to 2013. Non-transgenic cotton ‘CCRI 49’ was used as the control, and transgenic Bt cotton ‘CCRI 41’ was used as the test material. Effects of transgenic Bt cotton on arthropod communities provide an important theoretical basis for the comprehensive management of cotton insect pests and ecological control, as well as a scientific reference for the evaluation of the environmental safety of transgenic Bt cotton. In addition, sustainable development and use, which are in accordance with ecological succession, can be adopted on the basis of production and need for pest control in cotton plants. In this study, arthropod communities were systematically investigated in transgenic Bt cotton ‘CCRI 41’ and conventional cotton ‘CCRI 49’ fields, from 2009 to 2013. In addition, meteorological factors during these five consecutive years were considered when analyzing the changing trends of relevant factors in the cotton field arthropod communities. The results showed that, during 2009-2013, the number of "orders" in the insect community, pest sub-community, and natural enemy sub-community in the "CCRI 41" cotton fields increased in comparison with the control cotton fields, but the differences were not significant. The number of "families," "species," and "total number of individuals" showed an increasing trend over the first 3 years and then declined in the last 2 years (2012 and 2013). The differences were significant in some years, which might be due to the meteorological conditions, while fluctuations were within statistical limits in other years. The diversity indices of the insect and pest sub-communities showed declining trends, which were statistically significant in 2013 but not significant in the other years. There was no significant change in the diversity index of the natural enemy sub-community. In addition, there was no significant change in the uniformity indices of the insect, pest, and natural enemy sub-communities. The dominant concentration indices of the insect and pest sub-communities increased over the 5-year period, but the increase was only significant in 2013. There was no significant change in the dominant concentration index of the natural enemy sub-community in 2009-2013.There were no significant changes in the structure or composition of the cotton field insect, pest, or natural enemy sub-communities in Bt cotton ‘CCRI 41’ fields, nor were there any changes in the diversity, uniformity, or dominant concentration indices. It can be inferred from the results that there were no significant changes in the structure, composition, and biodiversity of the arthropod, pest, and natural enemy sub-communities in Bt cotton fields during the planting period. However, this study was a short-term comparative investigation of only one pair of cotton varieties. The long-term effects of planting transgenic Bt cotton on the structure, composition, and biological diversity of arthropod communities need to be investigated and monitored in the future. This will provide scientific data for a long-term safety risk assessment of transgenic Bt cotton. 参考文献 相似文献 引证文献

Influence of Row Spacing, Herbicide Technology, and Tillage on Fiber Quality and Economic Returns

Agricultural producers are faced with a range of conditions that influence their profitability, from weather variability to weed, insect, and disease pressure. Adoption of new production methods to address these conditions can produce higher or lower yields, as well as differing cotton (Gossypium hirsutum L.) fiber quality. The objective of this study was to evaluate the effect of row spacing, herbicide technology, and tillage on fiber quality attributes, quality price difference, ginning percentage, and net returns above variable treatment costs (NR) using data from a field experiment conducted in Alabama from 2004 to 2006. Treatments included nontransgenic, glyphosate-tolerant, and glufosinate-tolerant cotton varieties; conservation tillage and conventional tillage; and standard row (102-cm) and narrow row (38-cm) spacing. Ordered multinomial mixed logit models were used to evaluate fiber quality attributes, quality price difference, and ginning percentage, and a linear mixed model was use to evaluate NR. Fiber quality attributes were most commonly impacted by variety and tillage. Across all fiber quality attributes, nontransgenic and glufosinate-tolerant varieties had a higher probability of producing premium cotton than the glyphosate-tolerant variety due to premiums from micronaire, strength, and uniformity values. Conservation tillage systems had a higher probability of higher values for color grade, staple, and uniformity. Glyphosate-tolerant cotton and cotton grown in a conventional tillage system were more likely to have higher ginning percentages. Spacing and variety were influential in determining NR. These results indicate the importance of considering, not only seed cotton yield, but also fiber quality and ginning percentage when making production decisions.

Effects of transgenic cotton expressing chitinase and glucanase genes on the diversity of soil bacterial community

The transgenic cotton expressing chitinase and glucanase genes was studied using nontransgenic cotton as a control. Specifically, the effects of exogenous genes on bacterial community diversity in rhizospheres of cotton at stages of seedling, budding, boll forming and boll opening were evaluated through comparing the number of cultivable bacteria and analyzing 16S rRNA gene clone libraries. The results showed that the number of cultivable bacteria was not affected by exogenous genes but the cotton growth period, and the number peaked at the stage of boll forming with vigorous metabolism. The 16S rRNA gene clone library prepared from soil bacteria in rhizospheres of transgenic and nontransgenic cotton at different stages contained 2400 clones which covered 283 genera. Among them, Acidobacterium was the most dominant group which contained 642 clones, followed by unclassified bacterium and Flavisolibacter. Compared with nontransgenic cotton, the rhizosphere bacterial diversity of transgenic cotton exhibited lower level at the same growth stage, however, their common bacterial communities increased with growth and development. Our results suggest that chitinase and glucanase genes decrease the rhizosphere bacterial diversity at distinct degrees, however, the difference of bacterial diversity between transgenic and nontransgenic cotton reduces gradually with the extension of cultivation period.

Comparative proteomics of Bt-transgenic and non-transgenic cotton leaves

BackgroundAs the rapid growth of the commercialized acreage in genetically modified (GM) crops, the unintended effects of GM crops’ biosafety assessment have been given much attention. To investigate whether transgenic events cause unintended effects, comparative proteomics of cotton leaves between the commercial transgenic Bt + CpTI cotton SGK321 (BT) clone and its non-transgenic parental counterpart SY321 wild type (WT) was performed.ResultsUsing enzyme linked immunosorbent assay (ELISA), Cry1Ac toxin protein was detected in the BT leaves, while its content was only 0.31 pg/g. By 2-DE, 58 differentially expressed proteins (DEPs) were detected. Among them 35 were identified by MS. These identified DEPs were mainly involved in carbohydrate transport and metabolism, chaperones related to post-translational modification and energy production. Pathway analysis revealed that most of the DEPs were implicated in carbon fixation and photosynthesis, glyoxylate and dicarboxylate metabolism, and oxidative pentose phosphate pathway. Thirteen identified proteins were involved in protein-protein interaction. The protein interactions were mainly involved in photosynthesis and energy metabolite pathway.ConclusionsOur study demonstrated that exogenous DNA in a host cotton genome can affect the plant growth and photosynthesis. Although some unintended variations of proteins were found between BT and WT cotton, no toxic proteins or allergens were detected. This study verified genetically modified operation did not sharply alter cotton leaf proteome, and the target proteins were hardly checked by traditional proteomic analysis.Electronic supplementary materialThe online version of this article (doi:10.1186/s12953-015-0071-8) contains supplementary material, which is available to authorized users.

Diversity of arthropod community in transgenic poplar-cotton ecosystems.

Poplar-cotton agro-ecosystems are the main agricultural planting modes of plain cotton fields in China. Here, we performed a systematic survey of the diversity and population of arthropod communities in four different combination of poplar-cotton eco-systems, including I) non-transgenic poplar and non-transgenic cotton fields; II) non-transgenic poplar and transgenic cotton fields [Bacillus thuringiensis (Bt) cotton]; III) Bt transgenic poplar (high insect resistant strain Pb29) and non-transgenic cotton; and IV) transgenic poplar and transgenic cotton fields, over a period of 3 years. Based on the statistical methods used to investigate community ecology, the effects of transgenic ecosystems on the whole structure of the arthropod community, on the structure of arthropods in the nutritive layer, and on the similarity of arthropod communities were evaluated. The main results were as follows: the transgenic poplar-cotton ecosystem has a stronger inhibitory effect on insect pests and has no impact on the structure of the arthropod community, and therefore, maintains the diversity of the arthropod community. The character index of the community indicated that the structure of the arthropod community of the transgenic poplar-cotton ecosystem was better than that of the poplar-cotton ecosystem, and that system IV had the best structure. As for the abundance of nutritional classes, the transgenic poplar-cotton ecosystem was also better than that of the non-transgenic poplar-cotton ecosystem. The cluster analysis and similarity of arthropod communities between the four different transgenic poplar-cotton ecosystems illustrated that the structure of the arthropod community excelled in the small sample of the transgenic poplar-cotton ecosystems.

Impacts of the transgenic CrylAc and CpTI insect-resistant cotton SGK321 on selected soil enzyme activities in the rhizosphere

Transgenic CrylAc and CpTI insect-resistant cotton SGK321 is widely adopted for many years in several regions of China, however the understanding of its potential effects on soil enzyme activities is not studied. The impacts of transgenic cotton SGK321 on dehydrogenase, urease and phosphatase activities in rhizosphere soil were investigated in a two-year field study in Northern China. Rhizosphere soil enzyme activities between transgenic cotton SGK321 and its non-transgenic parental cotton Shiyuan 321 were found to differ at senescence. However compared to the plant growth stages and cotton cultivar, the impacts of the transgenic trait were minor or transient. The principal component analysis also showed no significant or minor difference in the activities of dehydrogenase, urease and phosphatase in the rhizosphere soil of transgenic cotton SGK321 and its counterpart. Our results indicated that the transgenic cotton SGK321 has no apparent impact on dehydrogenase, urease and phosphatase activities in rhizosphere soil.

Effects of Bt+CpTI transgenic cotton on the performance of <em>Tetranychus</em><em> turkestani</em> (Acari: Tetranychidae)

Transgenic cotton is very effective in controlling targeted pests such as cotton bollworm (Helicoverpa armigera). However, increases in spider mite (Acari: Tetranychidae) populations have been reported in fields of transgenic cotton. The objectives of our laboratory experiments were (i) to determine host plant preference (transgenic or non-transgenic cotton) of T. turkestani females and (ii) to compare the life table parameters of T. turkestani females reared on transgenic or non-transgenic cotton. Enzyme-linked immunosorbent assays indicated that T. turkestani females reared on transgenic cotton leaves contained 14.9±0.23 μg Bt toxic protein per gram fresh weight, about 57.4% toxin in the transgenic cotton leaves. Results of dual-choice disc tests showed that T. turkestani females preferred to feed and lay eggs on non-transgenic cotton. Food source (transgenic or non-transgenic cotton) had no significant effect on the life table parameters of T. turkestani females. We conclude that increases in the population of spider mites in fields of transgenic cotton cannot be attributed to host plant preference or to the effects of Bt toxic protein on the non-targeted arthropods life cycle. Additional studies should be done to determine if the increases are due to less insecticide application or less competition with primary insects in transgenic cotton fields.

Construction of a standard reference plasmid containing seven target genes for the detection of transgenic cotton

Insect resistance and herbicide tolerance are the dominant traits of commercialized transgenic cotton. In this study, we constructed a general standard reference plasmid for transgenic cotton detection. Target genes, including the cowpea trypsin gene cptI, the insect resistance gene cry1Ab/1Ac, the herbicide tolerance gene cp4-epsps, the Agrobacterium tumefaciens nopaline synthase (Nos) terminator that exists in transgenic cotton and part of the endogenous cotton SadI gene were amplified from plasmids pCPT1, pBT, pCP4 and pBI121 and from DNA of the nontransgenic cotton line K312, respectively. The genes cry1Ab/1Ac and cptI, as well as cp4-epsps and the Nos terminator gene, were ligated together to form the fusion genes cptI-Bt and cp4-Nos, respectively, by overlapping PCR. We checked the validity of genes Sad1, cptI-Bt and cp4-Nos by DNA sequencing. Then, positive clones of cptI-Bt, cp4-Nos and Sad1 were digested with the corresponding restriction enzymes and ligated sequentially into vector pCamBIA2300, which contains the CAMV 35S promoter and nptII gene, to form the reference plasmid pMCS. Qualitative detection showed that pMCS is a good positive control for transgenic cotton detection. Real-time PCR detection efficiencies with pMCS as a calibrator ranged from 94.35% to 98.67% for the standard curves of the target genes (R2⩾0.998). The relative standard deviation of the mean value for the known sample was 11.95%. These results indicate that the strategy of using the pMCS plasmid as a reference material is feasible and reliable for the detection of transgenic cotton. Therefore, this plasmid can serve as a useful reference tool for qualitative and quantitative detection of single or stacked trait transgenic cotton, thus paving the way for the identification of various products containing components of transgenic cotton.

Effects of the transgenic CrylAc and CpTI insect-resistant cotton SGK321 on rhizosphere soil microorganism populations in northern China

Transgenic CrylAc and CpTI insect-resistant cotton SGK321 has been widely adopted for many years in several regions of China, however the understanding of its potential effects on soil microorganisms is limited. The impact of transgenic cotton SGK321 on microorganism populations in rhizosphere soil was investigated. The numbers of bacteria, fungi, and actinomycetes were measured by counting colony-forming units after incubation on appropriate medium in a two-year field study in the northern China. Rhizosphere soil microorganism populations between transgenic cotton SGK321 and its non-transgenic parental cotton or conventional cotton were different at some plant growth stages and/or in some years. However compared to the plant growth stage and cotton cultivar, the impacts of the transgenic trait were slight or transient. The principal component analysis also showed no significant or minor difference in the numbers of bacteria, fungi, and actinomycetes in rhizosphere soil between transgenic cotton SGK321 and its non-transgenic parental cotton. These results suggest that the transgenic cotton SGK321 has no apparent impact on microorganism populations in rhizosphere soil.

Effects of Transgenic Cry1Ac + CpTI Cotton on Non-Target Mealybug Pest Ferrisia virgata and Its Predator Cryptolaemus montrouzieri

Recently, several invasive mealybugs (Hemiptera: Pseudococcidae) have rapidly spread to Asia and have become a serious threat to the production of cotton including transgenic cotton. Thus far, studies have mainly focused on the effects of mealybugs on non-transgenic cotton, without fully considering their effects on transgenic cotton and trophic interactions. Therefore, investigating the potential effects of mealybugs on transgenic cotton and their key natural enemies is vitally important. A first study on the effects of transgenic cotton on a non-target mealybug, Ferrisia virgata (Cockerell) (Hemiptera: Pseudococcidae) was performed by comparing its development, survival and body weight on transgenic cotton leaves expressing Cry1Ac (Bt toxin) + CpTI (Cowpea Trypsin Inhibitor) with those on its near-isogenic non-transgenic line. Furthermore, the development, survival, body weight, fecundity, adult longevity and feeding preference of the mealybug predator Cryptolaemus montrouzieri Mulsant (Coleoptera: Coccinellidae) was assessed when fed F. virgata maintained on transgenic cotton. In order to investigate potential transfer of Cry1Ac and CpTI proteins via the food chain, protein levels in cotton leaves, mealybugs and ladybirds were quantified. Experimental results showed that F. virgata could infest this bivalent transgenic cotton. No significant differences were observed in the physiological parameters of the predator C. montrouzieri offered F. virgata reared on transgenic cotton or its near-isogenic line. Cry1Ac and CpTI proteins were detected in transgenic cotton leaves, but no detectable levels of both proteins were present in the mealybug or its predator when reared on transgenic cotton leaves. Our bioassays indicated that transgenic cotton poses a negligible risk to the predatory coccinellid C. montrouzieri via its prey, the mealybug F. virgata.

Bt-transgenic cotton is more sensitive to CeO2 nanoparticles than its parental non-transgenic cotton

Because genetically modified crops are developing widely in the world while nanoparticles (NPs) are being synthesized and applied in various fields, they will have many opportunities for interactions in the future. The effects of NPs on genetically modified crops therefore require investigation. In the present study, CeO2 NPs were revealed to have toxic effects on root biomass of Bt 29317 at 100 and 500mgL−1, but had no toxic effects on Jihe 321. Besides, we also studied the effects of CeO2 NPs on nutrient element uptake in transgenic cotton, and found that contents of most nutrient elements (Fe, Ca, Mg, Zn and Na) in roots of Bt 29317 were affected at lower NP concentrations (100mgL−1) compared with Jihe 321. In addition, ICP-MS analysis revealed that CeO2 NPs were more heavily adsorbed by roots of Bt 29317 than Jihe 321, whereas fewer CeO2 NPs were transported from roots to shoots of Bt 29317 than its non-transgenic counterpart. These data confirm that Bt 29317 is more sensitive to CeO2 NPs than its parental non-transgenic cotton, indicating that nanomaterials are potentially more detrimental to transgenic plants than conventional ones.

The substantive equivalence of transgenic (Bt and Chi) and non-transgenic cotton based on metabolite profiles

Compositional studies comparing transgenic with non-transgenic counterpart plants are almost universally required by governmental regulatory bodies. In the present study, two T(2) transgenic cotton lines containing chitinase (Line 11/57) and Bt lines (Line 61) were compared with non-transgenic counterpart. To do this, biochemical characteristics of leaves and seeds, including amino acids, fatty acids, carbohydrates, anions, and cations contents of the studied lines were analyzed using GC/MS, high-performance liquid chromatography (HPLC), and ion chromatography (IC) analyzers, respectively. polymerase chain reaction (PCR) and Western blot analyses confirmed the presence and expression of Chi and Bt genes in the studied transgenic lines. Although, compositional analysis of leaves contents confirmed no significant differences between transgenic and non-transgenic counterpart lines, but it was shown that glucose content of chitinase lines, fructose content of transgenic lines (Bt and chitinase) and asparagine and glutamine of chitinase lines were significantly higher than the non-transgenic counterpart plants. Both the transgenic lines (Bt and chitinase) showed significant decrease in the amounts of sodium in comparison to the non-transgenic counterpart plants. The experiments on the seeds showed that histidine, isoleucine, leucine, and phenylalanine contents of all transgenic and non-transgenic lines were the same, whereas other amino acids were significantly increased in the transgenic lines. Surprisingly, it was observed that the concentrations of stearic acid, myristic acid, oleic acid, and linoleic acid in the chitinase line were significantly different than those of non-transgenic counterpart plants, but these components were the same in both Bt line and its non-transgenic counterpart. It seems that more changes observed in the seed contents than leaves is via this point that seeds are known as metabolites storage organs, so they show greater changes in the metabolites contents comparing to the leaves.