Bt Protein Content Research Articles

Exogenous Hormones Affect Bt Protein Content of Two Bt Cotton Cultivars

Bacillus thuringiensis (Bt) transgenic cotton (Gossypium hirsutum L.) has been widely planted in Asia. However, efficacy of the Bt protein to kill pests has been inconsistent. Effects of gibberellic acid (GA3) and dimethylpiperidinium chloride (DPC) on boll Bt protein content were investigated on ‘Sikang1’ and ‘Siza3.’ Treatment of DPC increased the Bt protein contents in carpel wall and cotton seed at 10 d after flowering (DAF) and 30 DAF in 2014 and 2015. However, Bt protein contents of the GA3 treatment only at 30 DAF were higher for both cultivars in comparison to the control. To further investigate the mechanism, we found the ability of protein synthesis (indicated by enzyme activities of nitrate reductase [NR], glutamic‐pyruvic transaminase [GPT], and glutamic oxaloacetate transaminase [GOT], as well as contents of total nitrogen, free amino acid, and soluble protein) in bolls increased markedly with the application of DPC for both cultivars. Further analysis showed that there were positive linear correlations between Bt protein content and NR, GPT, and GOT activities and total nitrogen and soluble protein contents (r = 0.925∗∗, r = 0.691∗∗, r = 0.703∗∗, r = 0.682∗, r = 0.693∗∗, respectively) in carpel wall of bolls. Thus, DPC is potentially an effective chemical application to increase boll Bt protein content.Core Ideas Dimethylpiperidinium chloride (DPC) application can bolster boll insect resistance. Significant linear positive correlation between Bt protein content and ability of synthesis the protein was found in boll shell. DPC increases Bt protein content through increasing ability of synthesis the protein.

Recovery characteristics of Bt insecticidal protein and relative physiological mechanisms after high temperature stress termination in square of Bt cotton

The experiments were conducted at Key Laboratory of Genetics and Physiology of Yangzhou University. The conventional cultivar Sikang-1 and hybrid cultivar Sikang-3 were used as the experimental materials. The potted cotton at squaring stage was moved to artificial climatic chamber with 38°C for 72 h , and 38°C for 96 h respectively in 2017 and 2018 cotton growth season, and moved to natural conditions, then the squares were collected to measure the Bt protein concentration and nitrogen metabolic physiology at 0, 12, 24, 48, 72, 96 hours respectively after the high temperature termination. The square Bt insecticidal protein contents were able to recover to the corresponding control level, the time for the recovery was in need of longer as the stressed high temperature period increased. In 72 h high temperature treatment, the square Bt insecticidal protein content could recover to the corresponding control level at 72 h for Sikang-1 and at 48 h for Sikang-3. In 96 h high temperature treatment, the square Bt insecticidal protein content could recover to the corresponding control level at 96 h for Sikang-1 and at 72 h for Sikang-3. There were significantly positive correlations of Bt toxin content with soluble protein content, glutamate pyruvate transaminase activity and glutamate oxaloacetate transaminase activity (the correlation coefficients were 0.964**, 0.981**, and 0.971**, respectively), and significantly negative correlations of Bt toxin content with free amino acid contents, and activitied of protease and peptidase (the correlation coefficients were -0.894**, -0.912**, and -0.834**, respectively). Therefore, the recovery degree of Bt insecticidal protein content of cotton square can be predicted according to the duration of high temperature stress, reasonably controlling Helicoverpa armigera and related pests in production.

Development, survival, and feeding behavior of Helicoverpa zea (Lepidoptera: Noctuidae) relative to Bt protein concentrations in corn ear tissues.

The corn earworm, Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae), preferentially oviposits and feeds on ears of corn (Zea mays L.) and can be managed using transgenic hybrids that produce insecticidal proteins from the bacterium Bacillus thuringiensis (Bt). Concentrations of Bt proteins can vary spatially and temporally in plant tissues, creating a heterogeneous environment that can increase the risk of resistance development. We planted small-plot trials of nine Bt and non-Bt corn hybrids in South Carolina in 2016 and 2017 and investigated the development, survival, feeding injury, and feeding behavior in corn ear tissues. ELISA was used to quantify the concentrations of Cry1F and Cry2Ab2 in young silk, old silk, maternal tip tissue, kernels, and husk. Cry1F and Cry2Ab2 significantly varied with silk age and both proteins were generally highest in the silk and tip tissue. Hybrids with pyramided proteins significantly reduced feeding injury to the silk, tip, and kernel ear tissues, which was less apparent with single Bt protein hybrids. The pyramided hybrid expressing Vip3A incurred no injury to either the ear tip or kernels, and only eight 1st instar larvae were collected in the silk of 520 sampled ears. Age of larvae significantly varied among ear tissues but not between hybrids. Depending on hybrid family, mean larval instar in the silk, tip, and kernels was 1st or 2nd, 3rd, and 5th, respectively. Instar-specific feeding penetrance into corn ears increased with age but did not differ between hybrids. We characterized the instar- and tissue-specific feeding behavior of H. zea larvae but did not detect differences in feeding behavior between Bt and non-Bt hybrids. Implications for resistance management strategies such as seed mixtures are discussed.

Amino acids application enhances flowers insecticidal protein content in Bt cotton

BackgroundLow insecticidal protein expression at reproductive organs affect insect resistance in Bt transgenic cotton. In order to enhance flower insecticidal protein expression, the conventional cultivar Sikang1 (S1) and the hybrid cultivar Sikang3 (S3) were used as experimental materials; the applications of selected 5 types of amino acids and 21 types of amino acids were sprayed on the flowers in 2016 and 2017 cotton growing seasons.ResultsThe flower Bt protein contents increased significantly under the two amino acid treatments in both cultivars, the Bt protein concentration increased by 15.2 to 25.8% compared with the control. However, no significant differences were detected between the two treatments of amino acid application. Increased amino acid and soluble protein contents, enhanced GPT, GOT, protease,and peptidase activities were observed under the amino acid application at the flowering stage.ConclusionsThese results suggest that exterior application of the amino acids treatments could bolster the flower insecticidal protein expression.

Square Insecticidal Protein Concentration Relate to its Biomass in Bt Cotton

Core Ideas Cultivar with high square biomass for individual and whole plant had higher insecticidal protein content. The increased square biomass by mepiquat chloride application enhaced Bt protein concentration. The decreased square biomass by nitrogen deficit reduced square Bt protein concentration. The square insecticidal protein concentration relates to its biomass. Bt transgenic cotton has been cultivated in China and many other cotton production areas in the world. However, the insecticidal efficacy is often low for the reproductive organs, especially for the cultivars with a big boll in China. The objective of the study focused on the effect of square biomass on the Bt protein concentration during the squaring period for Bt cotton. In the variety effect study in 2015 and 2016, two hybrid Bt cultivars (Sikang3 and Sumian29) and two conventional Bt cultivars (Sikang1 and Nucotn33B) were compared for square biomass and Bt toxin content from 15 to 25 d after square appearance (DASP) during the cotton growing seasons. Cultivars with high square biomass for individual and whole plant had higher insecticidal protein content. In the cultural practice effect study in 2017, the experiment of mepiquat chloride (MC) dose and different nitrogen deficit extents were designed to further investigate the relationship between square biomass and square Bt protein concentration. The MC application significantly increased square mass and square Bt protein content. In contrast, the nitrogen deficit decreased square mass together with square insecticidal protein concentration. The positive correlation between square biomass (the individual square biomass and the square biomass per plant) and square insecticidal protein content was highly significant in variety study and cultural practice study. The results indicated that increment of square development by variety selection and cultural practice could increase insect resistance during squaring period of Bt cotton.

Impacts of soil salinity on Bt protein concentration in square of transgenic Bt cotton.

Insect-resistance of transgenic Bacillus thuringiensis (Bt) cotton varies among plants organs and with different environmental conditions. The objective of this study was to examine the influence of soil salinity on Bt protein concentration in cotton squares and to elucidate the potential mechanism of Bt efficacy reduction. Two cotton cultivars (NuCOTN 33B and CCRI 07, salt-sensitive and salt-tolerant) were subjected to salinity stress under four natural saline levels in field conditions in 2015 and 2016 and seven regimes of soil salinity ranged from 0.5 to 18.8 dS m-1 in greenhouse conditions in 2017. Results of field studies revealed that Bt protein content was not significantly changed at 7.13 dS m-1 salinity, but exhibited a significant drop at the 10.41 and 14.16 dS m-1 salinity. The greenhouse experiments further showed similar trends that significant declines of the insecticidal protein contents in squares were detected when soil salinity exceeded 9.1 dS m-1. Meanwhile, high salinity resulted in significant reduction in contents of soluble protein and total nitrogen, activities of nitrate reductase (NR), glutamine synthetase (GS) and glutamic-pyruvic transaminase (GPT), but increased amino acid content, activities of protease and peptidase in cotton squares. High salinity also decreased root vigor (RV), root total absorption area (RTA) and root active absorption area (RAA). The extent of decrease of Bt protein content was more pronounced in NuCOTN 33B than CCRI 07, and CCRI07 exhibited stronger enzymes activities involved in square protein synthesis and higher levels of RV, RTA and RAA. Therefore, the results of our present study indicated that insecticidal protein expression in cotton squares were significantly affected by higher salinity (equal to or higher than 9.1 dS m-1), reduced protein synthesis and increased protein degradation in squares and reduced metabolic activities in roots might lead to the decrease of Bt protein content in squares.

Effect of soil salinity on insecticidal protein expression in flower buds of Bt cotton.

To clarify the effects of soil salinity on the insect-resistance of flower buds in transgenic Bt cotton of Xinmian 33B (salt-sensitive) and Zhong 07 (salt-tolerant), five levels (0, 0.15%, 0.30%, 0.45% and 0.60%) of soil salinity were set to investigate the impacts of soil salinity on Bt protein content, relative expression of Bt gene, activities of nitrogen metabolism-related enzymes and substances in flower buds during flowering stage. The results showed that Bt protein contents of flower buds decreased with increasing soil salinity. The Bt protein contents of flower buds decreased significantly when the soil salinity level was above 0.30% in both cotton cutivars. Greater reduction of Bt protein content occurred under severe than moderate soil salinity stress. However, the relative expression of Cry1Ac gene increased in flower buds of both cultivars when the stress level increased. Greater decreases of Bt protein content of flower buds was observed in Xinmian 33B compared to Zhong 07 under the same salinity level. The cultivars with greater reduction in Bt protein contents of flower buds also had greater reduction in the soluble protein content, glutamate pyruvate transaminase (GPT) and glutamic oxaloacetic transaminase (GOT) activities, and greater increments in free amino acid contents, protease activities and peptidase activities. Therefore, the decrease of Bt protein content was caused by decreased synthesis and increased decomposition of protein in flower buds of Bt cotton under soil salinity stress.

Effects of soil salinity on Bt protein content and nitrogen metabolic physiology in boll shell of Bt cotton

In order to clarify the effects of soil salinity on the insect-resistance of boll in transgenic Bt cotton, potted plants of two Bt cotton cultivars Xinmian 33B (salt-sensitive) and Zhong 07 (salt-tolerant) were exposed to five levels of soil salinity (0, 0.15%, 0.30%, 0.45% and 0.60%). The results showed that Bt protein content of boll shell decreased with increasing soil salinity. Compared with the control (0% soil salinity level), the Bt protein content of boll shell decreased significantly when the soil salinity level was above 0.15% for Xinmian 33B and above 0.30% for Zhong 07. The reduction extent of Bt protein content of boll shell at 30 days post anthesis (DPA) was greater than that at 10 DPA under the same soil salinity level. Significant reductions of soluble protein contents, nitrate reductase (NR), and glutamate pyruvate transaminase (GPT) activities were observed when the boll shell Bt protein content was significantly reduced. The content of free amino acid, protease, and peptidase activity of boll shell significantly increased when the soil salinity level was above 0.30%. In conclusion, soil salinity affected boll shell nitrogen metabolism and reduced Bt protein synthesis. Middle and high soil salinity levels could enhance decomposition of Bt protein, which further decreases the expression level of insecticidal protein.

Cultivation of Drought-Tolerant and Insect-Resistant Rice Affects Soil Bacterial, but Not Fungal, Abundances and Community Structures.

The impacts of rice varieties with stacked drought tolerance and insect resistance on soil microbiomes are poorly understood. Hence, the objective of this study was to investigate the effects resulting from the cultivation of the drought-tolerant and insect-resistant rice cultivar, Hanhui3T, on soil physical–chemical properties, and bacterial and fungal community composition. Soil samples of Hanhui3T and conventional rice varieties (Hanhui3 and Zhonghua11) were collected in triplicate at the booting stage, and bacterial and fungal population sizes and community structures were assessed using qPCR and Illumina MiSeq sequencing, respectively. The Bt protein concentration of Hanhui3T was significantly higher than that of Hanhui3 and Zhonghua11, while the pH of Hanhui3T was significantly lower. Bacterial population sizes and community composition were significantly different between Hanhui3T and Hanhui3 (or Zhonghua11), while no similar effects were observed for fungal communities. These differences suggest that the effect of Hanhui3T cultivation on bacterial community composition is stronger than the effect on fungal communities. Moreover, bacterial abundance was positively correlated to soil pH, while bacterial community structure variations were mainly driven by soil pH and Bt protein concentration differences. In conclusion, the abundances and structure of bacterial communities were altered in rhizosphere with Hanhui3T cultivation that changed soil pH and Bt protein concentrations, while fungal communities displayed no such responsiveness.

Efficiency of cotton bollworm (Helicoverpa armigera H\xfcbner) control of different Bt cotton varieties in North China

BackgroundThe cotton bollworm (Helicoverpa armigera) is one of cotton’s most destructive insect pests in terms of yield and quality. Since 1997, China has grown commercially available transgenic Bacillus thuringiensis (Bt) cotton. We aimed to investigate the variation in resistance of transgenic Bt cotton varieties to cotton bollworm in North China.MethodsPopulations of cotton bollworm were monitored from 2008 to 2015 in environments where Bt cotton was planted adjacent to other non-Bt crops. The study included 197 Bt cotton varieties planted in 42 counties/locations in three provinces (Hebei, Shandong and Henan) of North China, which were evaluated through field investigations, bioassays, and enzyme-linked immunosorbent assays (ELISA).ResultsThe average number of cotton bollworms never exceeded the action threshold (10 larvae per 100 cotton plants), however, their number reached 19.55 per 100 cotton plants in 2011. The ratios of damaged plants to total Bt cotton stem-tips, buds, and bolls was low except in 2010, when the ratios reached 1.82%, 2.09%, and 10.63%, respectively. The results of bioassay showed that the corrected mortality were higher at the second generation cotton bollworm stage than the third and fourth germination stages. Totally, Bt protein content declined sharply at the seedling stage from 2008 to 2015.ConclusionsThis study indicated that almost all Bt cotton varieties were capable to effectively control the populations of cotton bollworm in North China.

Nitrogen (N) Application Gradually Enhances Boll Development and Decreases Boll Shell Insecticidal Protein Content in N-Deficient Cotton.

Expression of insecticidal protein in transgenic Bacillus thuringiensis (Bt) is lower in cotton reproduction organs, especially during boll development period. The current study investigated the effects of nitrogen fertilization under nitrogen deficit on boll development and Bt toxin content in boll shell, which is the first target of boll worm harm. The protein synthesis and degradation in this process was also studied to uncover the underlying mechanism. Five nitrogen levels (under nitrogen deficiency) were imposed on two cultivars, Sikang3 (hybrid) and Sikang1 (conventional), at the Yangzhou University Farm, Yangzhou, China during 2015 to 2016 cotton growth seasons. Under nitrogen deficiency, enhanced nitrogen dose increased the boll number per plant, boll volume, boll weight, boll shell amino acid content, protease, and peptidase activities, but reduced boll shell Bt protein content, soluble protein content, glutamic pyruvic transaminase (GPT) and glutamate oxaloacetate transaminase (GOT) activities. There was a significant negative correlation between boll growth and boll shell insecticidal protein content under nitrogen deficiency, which was a result of uneven distribution of nitrogen in cotton bolls. Under increased nitrogen application, most nitrogen was transported and assimilated in boll seed instead of boll shell in developing cotton bolls, which resulted in decreased protein synthesis and increased protein degradation, and thus declined Bt protein content in boll shell.

Transfer of Cry1Ac and Cry2Ab proteins from genetically engineered Bt cotton to herbivores and predators.

With the cultivation of Bt cotton, the produced insecticidal Cry proteins are ingested by herbivores and potentially transferred along the food chain to natural enemies, such as predators. In laboratory experiments with Bollgard II cotton, concentrations of Cry1Ac and Cry2Ab were measured in Lepidoptera larvae (Spodoptera littoralis, Heliothis virescens), plant bugs (Euschistus heros), aphids (Aphis gossypii), whiteflies (Bemisia tabaci), thrips (Thrips tabaci, Frankliniella occidentalis), and spider mites (Tetranychus urticae). Tritrophic experiments were conducted with caterpillars of S. littoralis as prey and larvae of ladybird beetles (Harmonia axyridis, Adalia bipunctata) and lacewings (Chrysoperla carnea) as predators. Immunological measurements (ELISA) indicated that herbivores feeding on Bt cotton contained 5%-50% of the Bt protein concentrations in leaves except whiteflies and aphids, which contained no or only traces of Bt protein, and spider mites, which contained 7 times more Cry1Ac than leaves. Similarly, predators contained 1%-30% of the Cry protein concentration in prey. For the nontarget risk assessment, this indicates that Bt protein concentrations decrease considerably from one trophic level to the next in the food web, except for spider mites that contain Bt protein concentrations higher than those measured in the leaves. Exposure of phloem sucking hemipterans is negligible.

Effects of long-term cultivation of transgenic Bt rice (Kefeng-6) on soil microbial functioning and C cycling

Understanding how soil ecosystem responds to transgenic Bacillus thuringiensis (Bt) rice is necessary for environmental risk assessment. While the influences of short-term cultivation of Bt rice on soil properties have been reported previously, little is known about the long-term effects of Bt rice on soil ecosystems. In this study, soil samples were taken from a long-term rice cultivation site in Fujian Province, China, where transgenic Bt rice (Kefeng-6) and its non-Bt parent breed (Minghui-86) had been continuously cultivated for 8 years. Soil Bt protein concentration and a total of 16 variables were analyzed to assess potential risks of soil health under Bt rice cultivation. The results revealed that soil Bt protein is unlikely to accumulate after Bt rice cultivated in the field, and no consistently significant changes were observed in soil enzymatic activities (catalase, dehydrogenase, acid phosphatase, and urease), microbial biomass (microbial carbon and nitrogen), total organic carbon, decomposition (soil respiration, Q10, and qCO2), soil nitrogen and phosphorus contents. Due to a local tradition that aboveground biomass was removed after harvest, the increased net primary productivity by Bt rice cultivation did not significantly change soil C cycling. Results of this study suggested that on the aspects of soil microbial functioning and C cycling, long-term cultivation of Bt rice is unlikely to result in significant effects on soil health.

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.

Amino acid composition and level affect Bt protein concentration in Bt cotton

Low insect resistance has been widely observed in Bacillus thuringiensis (Bt) transgenic cotton. The objective of this study was to investigate the effects of amino acid compositions and their concentration on the Bt toxin content in Bt cotton to gain a better physiological understanding of the observed phenomenon. In the 2010 study, the leaf amino acid composition, contents, and Bt protein concentrations were investigated under high temperature (36 °C) and low temperature(18 °C) at both square and boll stage respectively. In 2011, the leaves were sprayed with ethionone sulfoximine (MSO), aminooxyacetic acid (AOA) or combination of MSO and AOA at the two developing stages, and the leaf amino acid composition and Bt protein concentrations were investigated. In 2012, 17 amino acid compositions were used to spray cotton plants at the same two stages, and the Bt protein concentration were measured. In comparison to the control, more amino acids changed and greater concentration changes had been observed under the extreme temperatures at boll stage compared to that at square stage, which were conformity to the changes of the leaf Bt protein concentration. More amino acids reduced and greater reduction was noted with the application of MSO, AOA or combined MSO and AOA at boll period than that at square period, which resulted in the reduction of the leaf Bt toxin concentration. The external uses of Aspartic acid, Glutamic acid, Glycine, Proline, Tyrosine, Methionine, Phenylalanine, Histidine and Arginin enhanced the leaf Bt toxin level significantly at boll stage. However, only Aspartic acid, Glutamic acid, Proline, Methionine, Arginin could increase Bt protein concentration markedly at square period and the bolstered extent were low. Therefore, it was concluded that cotton amino acid composition and concentration was more sensitive to external factors at boll stage. In addition, there are close relationship between leaf Bt toxin content and Aspartic acid, Glutamic acid, Glycine, Proline, Tyrosine, Methionine, Phenylalanine, Histidine and Arginin and their concentrations.

Different response of an elite Bt restorer line of hybrid rice (Oryza sativa L.) in adaptation to nitrogen deficiency

Transgenic Bacillus thuringiensis (Bt) rice have been reported to acquire effective resistance against the target pests; however, the insertion and expression of alien Bt genes may have some unintended effects on the growth characteristics of rice. A screen-house experiment was conducted and repeated twice to investigate the growth characteristics and Bt protein expressions in two Bt rice lines [MH63 (Cry2A*) and MH63 (Cry1Ab/Ac)], which had different Bt protein expression levels in leaves, under zero nitrogen (N0) and recommended nitrogen (NR) fertilizer applications. Compared to the counterpart MH63, MH63 (Cry2A*) under N0 experienced accelerated leaf senescence and a lower internal N use efficiency (IEN), resulting in a 23.2% decrease in grain yield and a lower accumulated biomass. These variations were revealed to be correlated to the higher ratio of the Bt protein content to the soluble protein content (BTC/SPC) with a maximum value of 4.3‰ in MH63 (Cry2A*) leaves in the late growth stage. Under NR, no differences in growth characteristics between MH63 (Cry2A*) and MH63 were found. The growth characteristics of MH63 (Cry1Ab/Ac), with a lower BTC/SPC in the late growth stage compared to MH63 (Cry2A*), were identical to those of MH63 under the two N applications. Results show that the transgenic Bt rice MH63 (Cry2A*), with a relatively higher Bt protein expression in the late growth stage, had an inferior adaptation to nitrogen deficiency compared to its non-Bt counterpart. And this inferior adaptation was found to be correlated with the higher BTC/SPC in MH63 (Cry2A*) leaves in the late growth stage.

Effects of Soil Salinity on the Expression of Bt Toxin (Cry1Ac) and the Control Efficiency of Helicoverpa armigera in Field-Grown Transgenic Bt Cotton

An increasing area of transgenic Bacillus thuringiensis (Bt) cotton is being planted in saline-alkaline soil in China. The Bt protein level in transgenic cotton plants and its control efficiency can be affected by abiotic stress, including high temperature, water deficiency and other factors. However, how soil salinity affects the expression of Bt protein, thus influencing the control efficiency of Bt cotton against the cotton bollworm (CBW) Helicoverpa armigera (Hübner) in the field, is poorly understood. Our objective in the present study was to investigate the effects of soil salinity on the expression of Bt toxin (Cry1Ac) and the control efficiency of Helicoverpa armigera in field-grown transgenic Bt cotton using three natural saline levels (1.15 dS m-1 [low soil-salinity], 6.00 dS m-1 [medium soil-salinity] and 11.46 dS m-1 [high soil-salinity]). We found that the Bt protein content in the transgenic Bt cotton leaves and the insecticidal activity of Bt cotton against CBW decreased with the increasing soil salinity in laboratory experiments during the growing season. The Bt protein content of Bt cotton leaves in the laboratory were negatively correlated with the salinity level. The CBW populations were highest on the Bt cotton grown in medium-salinity soil instead of the high-salinity soil in field conditions. A possible mechanism may be that the relatively high-salinity soil changed the plant nutritional quality or other plant defensive traits. The results from this study may help to identify more appropriate practices to control CBW in Bt cotton fields with different soil salinity levels.

Effects of Waterlogging on Bt Protein Content and Nitrogen Metabolism in Square of Bt Cotton

Effects of Waterlogging on Bt Protein Content and Nitrogen Metabolism in Square of Bt Cotton

Transgenic Bt (Cry1Ab/Ac) rice lines with different genetic backgrounds exhibit superior field performance under pesticide-free environment

Transgenic rice with Cry Bacillus thuringiensis (Bt) genes have been developed in the last few decades. The performance of transgenic rice, especially the yield and resistance, must be meticulously evaluated prior to commercial production. In this study, yield and resistance performance of newly bred transgenic Bt (Cry1Ab/Ac) rice lines with different genetic backgrounds were first investigated under pesticide-free field environment. Transgenic Bt (Cry1Ab/Ac) rice lines showed high insect resistances and superior agronomic traits, resulting in obvious yield advantages ranging from 9.1% to 38.0% over their respective non-Bt control lines. Bt protein content (BTC) was similar among the Bt (Cry1Ab/Ac) rice lines in different years, while it was much higher in leaves than in stems of the Bt (Cry1Ab/Ac) rice lines. Different genetic backgrounds of Bt (Cry1Ab/Ac) rice lines affected the yield advantage but had no influence on the resistance and BTC. The results suggested that Bt (Cry1Ab/Ac) rice lines have gained obvious yield advantages and high resistances regardless of genetic background under pesticide-free environment.

The Effect of High-Temperature Stress on Bt Protein Content and Nitrogen Metabolism in the Boll Shell of Bt Cotton

The Effect of High-Temperature Stress on Bt Protein Content and Nitrogen Metabolism in the Boll Shell of Bt Cotton