This study was done to develop environmental risk assessments and a biosafety guide for insect-resistant genetically modified rice at a LMO (Living Modified Organism) isolation field. In the LMO quarantine area of Kyungpook National University, the species diversities and population densities of non-target insects found on insect-resistant genetically modified rice (Bt-T) resistant to Cnaphalocrocis medinalis and on non-GM rices (Dongjin-byeo and Ilmi-byeo) were investigated. The Bt-T event was therefore evaluated under field conditions to detect possible impacts on the above ground insects and spiders. The study compared transgenic rice and two non-GM reference rices, Dongjinbyeo and Ilmi-byeo, at Gunwi in Southern Korea in 2016 and 2017. A total of 9,552 individuals from 51 families and 11 orders were collected from the LMO isolation field. In the three types of rice fields, a total of 3,042 individuals from the Bt-T, 3,213 individuals from the Dongjin-byeo, and 3,297 individuals from the Ilmi-byeo were collected, respectively. There was no difference between the population densities of the non-target insect pests, natural enemies and other insects on the Bt-T and non-GM rices. The data of insect species population densities were subjected to principal component analysis (PCA), which not distinguished among the three varieties, GM and non-GM, reference cultivar in all cultivation years. However, PCA results were clearly separated the samples based on the cultivation years. These results suggest that insect species diversities and population densities during plants cultivation are determined by environmental factors (growing condition and seasons) rather than by genetic factors.

Insect-resistant transgenic (Bt-9) rice was generated by inserting the mCry1Ac1 a modified gene from the soil bacterium Bacillus thuringiensis into the genome of a conventional variety of rice (Ilmibyeo). With regard to the potential problems of safety, the non-target organism evaluation is required as an essential element for the environmental risk assessment of genetically modified (GM) crops. For biosafety assessment, we studied the effects on survival of cantor Daphnia magna, a commonly used as a model organism in ecotoxicological studies. D. magna fed on Bt-transgenic rice (Bt-9) and its near non-GM counterparts (Ilmibyeo) grown in the same environment (100% ground rice suspension). The Bt-9 rice was comfirmed to have the insertion of T-DNA and protein expression by the PCR and ELISA analysis. Feeding study showed similar cumulative immobility and abnormal response of Daphnia magna between Bt-9 rice and Ilmibyeo. 48hr-EC50 values of Bt-9 and Ilmi rice showed 4,400 mg/L (95% confidence limits: 3861.01 ~ 5015.01 mg/L) and 5,564mg/L (95% confidence limits: 4780.03 ~ 6476.93 mg/L) respectively. The rice NOEC (No observed effect concentration) value for D. magna was suggested 1,620mg/L. We conclude that the tested Bt-9 and Ilmi similar cumulative immobility for D. magna the widely used model organism. We found out that there is strong possibility that the growth of Bt-9 didn’t affect to non-target insects.

Bacillus thuringiensis (Bt) produces a variety of insecticidal crystal proteins and widely used as one of the most successful biological control agents. Recently, studies that introduce cry genes into crops to create pest resistance have made much progress, and the total area of land planted with Bt crops has increased substantially. In this study, pest resistance of 8 transgenic Bt rice events with a synthetic cry1Ac gene linked to rice rbcS-tp sequence were assessed under laboratory conditions. Bioassays were performed against Cnaphalocrocis medinalis, which is a significant pest of rice in Asia. C. medinalis larvae were shown to be susceptible to all eight events, even though there were differences between the causes of death. The results differed between developmental stages of the larvae, despite the fact that all 8 events led to high mortalities. These results may be a significant foundation for the evaluation of improved transgenic Bt rice.

To assess effects of Bt rice expressing a synthetic Cry1Ac1 gene for control Cnaphalocrocis medinalis (Guenee) (Lepidoptera: Pyralidae), we conducted laboratory tests to evaluate the potential impacts of Bt rice on non-target herbivore, non-target pollen-feeder and non-target predator. Also we investigated the community structure of arthropods in Bt and non-Bt rice fields during the rice-growing season in 2007 and 2008. There were no significant differences in development, survival and emergence of non-target herbivores, non-target pollen-feeder and non-target predators between Bt and non-Bt rice although tibia length of non-target predators with BPH feeding on Bt rice showed significantly longer than in non-Bt rice. In 2-year field study, a total of 43 familes in 10 orders were identified from 64,099 collected insects and a total of 29 species in 23 genera and 9 families were identified from 4,937 collected spiders. Abundance, Shannon’s index and family richness in insects and species richness in spiders were very similar between Bt and non-Bt rice for 2 years and there was no significant difference. The results indicated that the transgenic Cry1Ac rice tested in this study had no adverse effects on the rice insect and spider community structure in field condition and on the development, survival, emergence and adult fitness parameter of non-target arthropods in the laboratory conditions.

해충저항성 Bt벼와 낙동벼의 미꾸리(Misgurnus anguillicaudatus) 와 잉어(Cyprinus carpio)에 대한 급성독성시험을 실시한 결과 48시간 및 96시간-LC50은 1,000mg/L 이상으로 나타났다. 48시간 및 96시간 무영향농도(NOEC)는 1,000mg/L이었다. 급성독성 시험기간 중 해충저항성 Bt벼와 낙동벼간의 pH, DO, 수온, 체중 및 전장에 대한 유의적인 결과는 나타나지 않았다.

본 연구에서는 제초제 저항성인 Ab벼와 해충저항성 Bt벼, 이들의 모본인 동진벼의 현미에서 일반성분, 아미노산, 무기물, 지방산, 비타민 및 항영양소를 분석하여 유전자변형 벼(Ab, Bt)의 영양성분 조성 차이를 비교하고자 수행하였다. 그 결과 무기물의 철분이 모본인 동진벼와 유전자 변형 벼(Ab, Bt) 사이에 약 2배의 차이를 나타내었지만 codex 범위 내에 존재하였고, 비타민 류에서는 Bt벼와 동진벼 간의 유의적인 차이가 나타나지 않은 반면 Ab벼의 비타민 B1, B7, E에서 유의적인 차이를 보였다. 또한 트립신 저해제는 시료 모두에서 0.1 TIU/mg 미만으로 극소량 검출되었다. 총 46가지 분석 성분 중 17가지가 함량 및 조성에 유의적인 차이를 보였으나 이러한 차이는 이들의 모본인 동진벼, OECD 표준기술서, 그리고 일반 상업화 품종의 범위 내에 존재해 영양학적 측면에서 실질적으로 차이가 없는 것으로 판단된다.

The selectable marker-free rice plants containing mcry1Ac insecticidal gene isolated from Bacillus thuringiensis (Bt) were generated using a non-selection approach by Agrobacterium tumefaciens-mediated transformation. The nutritional composition of two lines of transgenic rice plants (RTB5 and RTB11) was compared with that of its non-transgenic counterpart. The results showed that, except for small differences in dietary fiber and some minerals, there was no significant difference between transgenic rice and conventional counterpart variety with respect to their nutrient composition. Most of measured levels of nutrients were within the range of values reported for other commercial cultivars, showing substantial equivalency. Therefore, the insertion of transgenes did not affect the nutritional composition of transgenic RTB5 and RTB11 rice grains.

본 연구는 Bacillus thuringiensis 유래의 살충성 mCry1Ac 유전자를 무선발 형질전환 방법으로 일미 벼에 도입하여 개 발된 마커프리 형질전환 Bt 벼 2계통의 일반성분 및 주요성분 (무기질, 아미노산) 함량을 확인하여 모본벼 및 다른 일반품 종과 함량차이를 비교 분석 함으로서 형질전환 벼의 영양성 분 동등성 여부를 확인하고자 수행되었다. 영양성분 분석결과 GM 벼 현미의 일반성분 조성 중 식이섬유 함량과 일부 무기 질 함량이 모본 벼인 일미와 비교하여 다소 유의적 차이가 있 었지만 일반품종에서 나타나는 함량범위 안에 포함되는 수치 이며, 아미노산 성분과 대부분의 일반성분 및 무기질의 함량 은 전반적으로 모본과 유의적 차이가 없었다. 따라서 형질전 환 벼에서 관찰된 일부 성분 차이는 Bt 유전자의 도입 효과가 아닌 재배 환경 및 토양성분의 차이에서 기인된 것으로 형질 전환에 의한 비의도적 영양성분 변화는 없는 것으로 판단된다.

The cultivation of genetically modified (GM) crops has increased due to their economic and agronomic advantages. Before commercialization of GM crops, however, we must assess the potential risks of GM crops on human health and environment. The aim of this study was to investigate the possible impact of Bt rice on the soil microbial community. Microbial communities were isolated from the rhizosphere soil cultivated with Bt rice and Nakdong, parental cultivar and were subjected to be analyzed using both culture-dependent and molecular methods. The total counts of bacteria, fungi, and actinomycetes in the rhizosphere of transgenic and conventional rice were not significantly different. Denaturing gradient gel electrophoresis (DGGE) analysis of PCR-amplified 16S rRNA genes revealed that the bacterial community structures during cultural periods were very similar each other. Analysis of dominant isolates in the rhizosphere cultivated with Bt and Nakdong rice showed that the dominant isolates from the soil of Bt rice and Nakdong belonged to the Proteobacteria, Cloroflexi, Actinobacteria, Firmicutes, and Acidobacteria. These results indicate that the Bt rice has no significant impact on the soil microbial communities during cultivation period. Further study remains to be investigated whether the residue of Bt rice effect on the soil environment.