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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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Applied Ecology / Yingyong Shengtai Xuebao is the property of Chinese Journal of Applied Ecology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chinese Journal of Applied Ecology / Yingyong Shengtai Xuebao is the property of Chinese Journal of Applied Ecology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Taking Bt cotton Sikang 1 (a conventional cultivar), Sikang 3 (a hybrid cultivar) from China and 99B (a conventional cultivar), Daiza 1 (a hybrid cultivar) from USA as test materials, the effects of different high temperatures on the square Bt proteins expression and nitrogen metabolic physiology were investigated. The results showed that the square Bt protein contents of the four cultivars decreased significantly above 38 °C compared with that at 32 °C. The higher the temperature was above 38 °C, the greater the reduction extent of the Bt protein content was. The square Bt protein contents of the hybrid cultivars were higher than that of the conventional cultivars, and were less reduced under the high temperature stress. The cultivars with bigger reductions in Bt protein content also showed greater reductions in the square soluble protein contents, pyruvic transaminase activities and glutamic oxaloacetic transaminase activities, while larger increments were detected for the square free amino acid contents, proteinsase activities and peptidase activities. [ABSTRACT FROM AUTHOR]

The spatiotemporal dynamics of Bt protein in soil and the change of soil nutrients in rhizosphere soil, root surface soil and soils at 0-20, 20-40 and 40-60 cm were measured in greenhouse experiments. Two Bt corns, 5422Bt1 and 5422CBCL, and their near isogenic nonBt variety 5422 were grown for 90 days and the crop residues were retained to soil. Results showed that 1.59 and 2.78 ng·g-1 Bt protein were detected in the rhizosphere soil with Bt corns 5422Bt1 and 5422CBCL immediately after harvest. However, there were only trace amounts of Bt protein (<0.5 ng·g-1) were detected in root surface soil after 90 days and in bulk soil in the two Bt corn treatments after 30, 60 and 90 days. When corn residues returned to soil, Bt protein declined rapidly within 3 days and only trace amounts of Bt protein were measured after 7 days. There were no significant differences in organic matter, available nutrient (alkaline hydrolytic N, available P, available K) or total nutrient (total N, total P, total K) in root surface soils and soils at 0-20 cm, 20-40 cm and 40-60 cm among the Bt and nonBt corns after 90 days. Sixty days after returning crop residues of 5422Bt1 to soil, the contents of organic matter and total N increased and the content of available K reduced significantly in the 0-20 cm soil depth. There were no significant differences in any other parameter at the 0-20 cm depth, neither for any parameter in the 20-40 cm and 40-60 cm soil depths compared to those in the nonBt corn 5422 treatment. There were no significant differences in soil nutrient contents in Bt corn 5422CBCL treatment compared to those in nonBt corn 5422 treatment except that available phosphorus content was reduced in root surface soils, and total P content increased at the 0-20 cm soil depth after 90 days. When crop residues of Bt corn 5422 CBCL were returned to soil, only available P content in the 0-20 cm soil layer was evidently higher compared to the soil receiving crop residues of nonBt corn 5422. Results suggested that Bt protein released from root and crop residues of Bt corns would not accumulate in soil, and growing Bt corns and returning crop residues to soil would have no significant effect on soil nutrients in general. [ABSTRACT FROM AUTHOR]

Different origins Bt cotton cultivars, including DP410B (conventional cultivar) and Daiza No.1 (hybridized cultivar) from US and Sikang No.1 (conventional cultivar) and Sikang No.3 (hybridized cultivar) from China, were taken as the test materials to investigate the effects of high temperature (37 °C) and different humidity (50%, 70%, and 90%) on the leaf Bt protein expression of Bt cotton. At high temperature, temperature and humidity had no significant effects on the leaf Bt rotein expression of the cultivars at peak squaring stage. At peak flowering stage, as compared with the control (25-30 °C and 60%-70% humidity), 37 °C and 50% humidity decreased the leaf Bt protein content of conventional cultivars significantly by 2.6%-3.0%. At peak bolling stage, compared with the control, 37 ° C and 50% humidity decreased the leaf Bt protein content of DP410B, Sikang No.1, and Sikang No.3 significantly by 3.3%-5.8%. Among the four cultivars, DP410B and Daiza No.1 had the highest leaf Bt protein content, while Sikang No.1 had the lowest one. [ABSTRACT FROM AUTHOR]

A pot experiment with red soil, yellow brown soil, and yellow cinnamon soil was conducted to detect the Bt protein content in rhizosphere and non-rhizosphere soils at different growth stages of transgenic Bt cotton and common cotton by using enzyme linked immunosorbent assay (ELISA). With the planting of transgenic Bt cotton, the Bt protein content in rhizosphere soil was significantly higher than that in non-rhizosphere soil; while in common cotton soils, there was no significant difference in the Bt protein content between rhizosphere soil and non-rhizosphere soil. At bud stage of transgenic Bt cotton, the Bt protein content in rhizosphere soil was in the order of yellow cinnamon soil > yellow brown soil > red soil, being 144%, 121%, and 238% of that in common cotton rhizosphere soil; at florescence stage of transgenic Bt cotton, the Bt protein content in rhizosphere soil was in the order of yellow brown soil > yellow cinnamon soil > red soil, being 156%, 116%, and 197% of that in common cotton rhizosphere soil, respectively. Regardless of planting Bt cotton or common cotton, the Bt protein content in rhizosphere and non-rhizosphere soils had an initial increase with the growth of cotton, peaked at florescence stage, and then decreased. Throughout the whole cotton growth period, the Bt protein content in transgenic Bt cotton rhizosphere soil was higher than that in Bt cotton non-rhizosphere soil, and also, higher than that in common cotton rhizosphere soil, indicating that transgenic Bt cotton could release its Bt protein to rhizosphere soil. [ABSTRACT FROM AUTHOR]

Transgenic Bt crops are widely planted around the world. With the quick development and extension of genetically modified crops, it is needed to make a deep study on the effects of Bt crops on soil ecosystem. This paper reviewed the research progress on the effects of transgenic Bt crops on the population dynamics and community structure of soil animals, e.g., earthworm, nematode, springtail, mite, and beetle, etc. The development history of Bt crops was introduced, the passway the Bt protein comes into soil as well as the residual and degradation of Bt protein in soil were analyzed, and the critical research fields about the ecological risk analysis of transgenic Bt crops on non-target soil animals in the future were approached, which would provide a reference for the research of the effects of transgenic Bt crops on non-target soil animals. [ABSTRACT FROM AUTHOR]