Comparison of three transgenic <i>Bt</i> rice lines for insecticidal protein expression and resistance against a target pest, <i>Chilo suppressalis</i> (Lepidoptera: Crambidae)

et al. 2018

Front. Plant Sci.

The environmental release and biosafety of transgenic Bt crops have attracted global attention. China has a large area of saline-alkali land, which is ideal for large-scale production of Bt transgenic rice. Therefore an understanding of the fitness of Bt transgenic rice in saline-alkaline soils and the ability to predict its long-term environmental effects are important for the future sustainable use of these crops. In the present study, we aimed to evaluate the fitness of cry1Ab/c transgenic rice in both farmland and natural ecosystems. Transgenic cry1Ab/c rice Huahui1, for which a national biosafety certificate was obtained, was grown on normal farmland and saline-alkaline soils in a glass greenhouse. The expression pattern of exogenous Cry1Ab/c protein, and vegetative and reproductive fitness of rice were assessed. The expression of the exogenous Cry1Ab/c protein in the transgenic rice grown on saline-alkaline soil was lower than that in the strain grown on farmland soil. Under both the soil conditions, vegetative growth abilities, as evaluated by tiller number and biomass, and reproductive growth abilities, as measured by filled grain number and filled grain weight per plant, showed a significantly higher fitness cost for Huahui1 than that for the parental rice Minghui63 grown under the same soil conditions. In saline-alkaline soil, the fitness cost of Huahui1was moderately higher than that of Minghui63. Therefore, the ecological risk of cry1Ab/c transgenic rice is not expected to be higher than that of parental rice Minghui63 if the former escapes into natural saline-alkaline soil. The results of the present study provide a scientific basis to improve environmental safety assessment of the insect-resistant transgenic rice strain Huahui1 before commercialization.

Section: Discussionsupporting

confidence: 91%

Fitness Cost of Transgenic cry1Ab/c Rice Under Saline-Alkaline Soil Condition

Song

et al. 2018

Front. Plant Sci.

“…() predicted that rice yield has to be increased to 7850 kg/ha by 2030, resulting in a total of 200 million kg of rice per year to feed the Chinese people. Among multiple constraints to rice production, insect pests are an important factor (Wang et al ., ,b). In Chinese rice ecosystems, four major lepidopteran pests – rice striped stem borer Chilo suppressalis (Family Crambidae), yellow stem borer Scirpophaga incertulas (Family Pyralidae), pink stem borer Sesamia inferens (Family Noctuidae) and rice leaf roller Cnaphalocrocis medinalis (Family Pyralidae) – cause serious damage to rice, resulting in severe yield losses in every crop season (Chen et al ., ).…”

Section: Issues Facing Rice Production In Chinamentioning

confidence: 99%

“…In addition, some Bt rice lines have been stacked with other types of transgenes, such as the bar gene for herbicide tolerance (Yao et al ., ) and xa21 for disease resistance (Wang et al ., ). Most of the Bt rice lines have been shown to express high resistance to target pests in laboratory and field trials (Cohen et al ., ; Han et al ., ; Sui et al ., ; Tang et al ., ; Tu et al ., ; Wang et al ., ,b; Zhang et al ., ; Zheng et al ., ). In 2009, China's Ministry of Agriculture issued biosafety certificates for commercial production of the Huahui 1 and Bt Shanyou 63 Bt rice lines in Hubei Province, which raised expectation that China would use GM technology in commercial rice production (http://www.rsc.org/chemistryworld/China/Issues/2010/April-June/GMHotlyDebatedInChina.asp).…”

Section: Issues Facing Rice Production In Chinamentioning

confidence: 99%

The development and status of Bt rice in China

Hallerman

Plant Biotechnology Journal

et al. 2015

SummaryMultiple lines of transgenic rice expressing insecticidal genes from the bacterium Bacillus thuringiensis (Bt) have been developed in China, posing the prospect of increases in production with decreased application of pesticides. We explore the issues facing adoption of Bt rice for commercial production in China. A body of safety assessment work on Bt rice has shown that Bt rice poses a negligible risk to the environment and that Bt rice products are as safe as non-Bt control rice products as food. China has a relatively well-developed regulatory system for risk assessment and management of genetically modified (GM) plants; however, decision-making regarding approval of commercial production has become politicized, and two Bt rice lines that otherwise were ready have not been allowed to enter the Chinese agricultural system. We predict that Chinese farmers would value the prospect of increased yield with decreased use of pesticide and would readily adopt production of Bt rice. That Bt rice lines may not be commercialized in the near future we attribute to social pressures, largely due to the low level of understanding and acceptance of GM crops by Chinese consumers. Hence, enhancing communication of GM crop science-related issues to the public is an important, unmet need. While the dynamics of each issue are particular to China, they typify those in many countries where adoption of GM crops has been not been rapid; hence, the assessment of these dynamics might inform resolution of these issues in other countries.

“…Throughout the growing season, different Bt rice lines display different expression dynamics of Cry proteins. To sum up, expression dynamics can be classified into three patterns: (i) declining expression, with high expression at an early stage (seedling stage) with gradually decreased levels at later stages; this is the most frequent pattern not only in Bt rice, but also in Bt cotton, soybean and maize [22,25,26,34,38,56,62,68]; (ii) increasing expression, namely low expression at an early stage with increased expression levels at later stages [17,69]; and (iii) relatively consistent expression [26,34,70]. Interestingly, relatively high Cry protein expression levels were detected in lines expressing cry2Aa or cry9C genes among the Bt rice lines.…”

Section: Bt Ricementioning

confidence: 99%

“…For example, the corrected mortalities of 1st- to 6th-instar C. suppressalis in 7-day bioassays feeding on rice expressing cry1Ac + CpTI genes were 89.6%, 87.1%, 72.37%, 50.0%, 26.6%, and 0%, respectively [59]. Since the expression of Bt proteins in rice normally shows a declining tendency with the growth of rice plants, the resistance to target pests generally declined over the growth stages of rice plants; at mature stage most Bt rice lines showed relatively poor anti-pest efficacy [34,55,56,71]. However, Bt rice lines such as Bt -DL, mfb-MH86, and Huahui 1 showed high and consistent pest resistance throughout the growing season due to the stable expression of Bt protein in rice plants [22,26,34].…”

Section: Bt Ricementioning

confidence: 99%

Development of Bt Rice and Bt Maize in China and Their Efficacy in Target Pest Control

Hallerman

Peng

et al. 2016

IJMS

Rice and maize are important cereal crops that serve as staple foods, feed, and industrial material in China. Multiple factors constrain the production of both crops, among which insect pests are an important one. Lepidopteran pests cause enormous yield losses for the crops annually. In order to control these pests, China plays an active role in development and application of genetic engineering (GE) to crops, and dozens of GE rice and GE maize lines expressing insecticidal proteins from the soil bacterium Bacillus thuringiensis (Bt) have been developed. Many lines have entered environmental release, field testing, and preproduction testing, and laboratory and field experiments have shown that most of the Bt rice and Bt maize lines developed in China exhibited effective control of major target lepidopteran pests on rice (Chilo suppressalis, Scirpophaga incertulas, and Cnaphalocrocis medinalis) and maize (Ostrinia furnacalis), demonstrating bright prospects for application. However, none of these Bt lines has yet been commercially planted through this writing in 2016. Challenges and perspectives for development and application of Bt rice and maize in China are discussed. This article provides a general context for colleagues to learn about research and development of Bt crops in China, and may shed light on future work in this field.