Edible Safety Assessment of Genetically Modified Rice T1C-1 for Sprague Dawley Rats through Horizontal Gene Transfer, Allergenicity and Intestinal Microbiota
October
Edible Safety Assessment of Genetically Modified Rice T1C-1 for Sprague Dawley Rats through Horizontal Gene Transfer, Allergenicity and Intestinal Microbiota
Kai Zhao 0 1
Fangfang Ren 1
Fangting Han 1
Qiwen Liu 1
Guogan Wu 0 1
Yan Xu 1
Jian Zhang 1
Xiao Wu 0 1
Jinbin Wang 0 1
Peng Li 0 1
Wei Shi 1
Hong Zhu 0 1
Jianjun Lv 1
Xiao Zhao 1
Xueming Tang 0 1
0 Biotechnology Research Institute, Shanghai Academy of Agricultural Sciences , Shanghai , People's Republic of China, 2 Key Laboratory of Agricultural Genetics and Breeding, Shanghai Academy of Agricultural Sciences , Shanghai , People's Republic of China, 3 College of Life and Environment Sciences, Shanghai Normal University , Shanghai , People's Republic of China, 4 Alberta Innovates-Technology Futures , Vegreville, Alberta , Canada , 5 National Center for Safety Evaluation of Drugs, Beijing Economic- Technological Development Area , Beijing , People's Republic of China, 6 Life Science College, Ningxia University , Yinchuan, Ningxia , People's Republic of China
1 Editor: Odir AntoÃnio Dellagostin, Universidade Federal de Pelotas , BRAZIL
In this study, assessment of the safety of transgenic rice T1C-1 expressing Cry1C was carried out by: (1) studying horizontal gene transfer (HGT) in Sprague Dawley rats fed transgenic rice for 90 d; (2) examining the effect of Cry1C protein in vitro on digestibility and allergenicity; and (3) studying the changes of intestinal microbiota in rats fed with transgenic rice T1C-1 in acute and subchronic toxicity tests. Sprague Dawley rats were fed a diet containing either 60% GM Bacillus thuringiensis (Bt) rice T1C-1 expressing Cry1C protein, the parental rice Minghui 63, or a basic diet for 90 d. The GM Bt rice T1C-1 showed no evidence of HGT between rats and transgenic rice. Sequence searching of the Cry1C protein showed no homology with known allergens or toxins. Cry1C protein was rapidly degraded in vitro with simulated gastric and intestinal fluids. The expressed Cry1C protein did not induce high levels of specific IgG and IgE antibodies in rats. The intestinal microbiota of rats fed T1C-1 was also analyzed in acute and subchronic toxicity tests by DGGE. Cluster analysis of DGGE profiles revealed significant individual differences in the rats' intestinal microbiota.
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OPEN ACCESS
Data Availability Statement: All relevant data are
within the paper and its Supporting Information
files.
Introduction
Rice (Oryza sativa L.) is one of the most important cereal crops and represents approximately
23% of all calories consumed worldwide [
1
]. Extensive cultivation of modern high yielding
varieties of crops has resulted in a significant increase in the yield of most food crops, including
http://www.stcsm.gov.cn/. The Science and
Technology Development Programme of Shanghai
Acedemy of Agricultural Sciences,2013(14), http://
www.saas.sh.cn/. The Science and Technology
Development Programme of Shanghai Acedemy of
Agricultural Sciences,2012(8), http://www.saas.sh.
cn/. The funders had no role in study design, data
collection and analysis, decision to publish, or
preparation of the manuscript.
rice. However, this has also augmented the development towards monocultures, which often
favors drastic increases in numbers of the insects that feed on these crops. Despite extensive
use of pesticides, an estimated 37% of crop production is lost due to pests and diseases, with at
least 13% directly due to insects [
2
]. Moreover, long-term and frequent use of chemical
insecticides has destroyed the balance of the ecosystem. Therefore, better and more sophisticated
forms of crop protection are important to ensure a stable food supply to meet the demand of
an ever-increasing global population.
During the past decade, genetic transformation has promoted a number of crop varieties
expressing transgene(s) from related or unrelated taxa. Bacillus thuringiensis (Bt) corn was
genetically modified by introducing the Bt gene to control insect pests [
3
]. Bt can produce
large crystalline parasporal inclusions (Cry proteins) during sporulation. Among them, the
Cry1C protein encoded by cry1C is highly toxic to about 35–40 insect species including rice
stem borers, Spodoptera exigua, beet armyworm and lepidopteran pests such as diamond
back moth (Plutella xylostella) [
4–6
]. The Cry1C toxin can also be combined with Cry1A
and Cry1Aa genes to develop two-toxin Bt crops, which can enhance the toxicity of Cry1C
against S. exigua and Helicoverpa armigera [
7
]. Cry1C toxin has high species-specific
toxicity against certain insects and can be used in developing transgenic crops to control
lepidopteran pests.
Insect-resistant Bt-transgenic crops were first grown commercially in 1996 [
8
], and since
then the planting area of Bt crops has increased steadily. Corn, cotton, canola and potatoes,
which were genetically engineered with a range of different Cry genes are commercially grown
around the world. Transgenic rice expressing Bt-Cry (...truncated)