Evaluation and Assessment of Biosafety for Bacillus thuringiensis (Bt)-transgenic Rice: Responses of Daphnia magna Fed on Bt-transgenic Rice Variety

Insect-resistant transgenic rice was developed by inserting the mCry1Ac1 a modified gene from the soil bacterium Bacillus thuringiensis (Bt). 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 rice and its near non-genetically modified (GM) counterparts (Nakdong) grown in the same environment (100% ground rice suspension). The Bt rice was comfirmed to have the insertion of T-DNA and protein expression by the polymerase chain reaction and ELISA analysis. Feeding study showed similar cumulative immobility and abnormal response of D. magna between Bt rice and non-GM counterparts. 48 h-$EC_{50}$ values of Bt rice and non-GM rice showed 4,429 and 2,889 mg/L respectively. The rice no observed effect concentration (NOEC) values for D. magna was suggested 1,000 mg/L. We conclude that the tested Bt-rice and Nakdong similar cumulative immobility for D. magna the widely used model organism. We found out that there is strong possibility that the growth of Bt rice didn't affect to non-target insects.

해충저항성 Bacillus thuringiensis (Bt) 벼의 환경위해성 평가: 해충저항성 Bt벼가 물벼룩(Daphnia magna)에 미치는 영향

해충저항성 Bacillus thuringiensis (Bt) 벼와 낙동벼의 비표적 생물체인 물벼룩(Daphniamagna)에 대한 급성독성시험을 실시한 결과, 해충저항성 Bt벼의 48시간-$EC_{50}$은 4,429.13 mg/L(95% 신뢰한계는 3908.130~5020.363 mg/L), 무영향 농도(NOEC)는 1,800 mg/L이었고, 낙동벼는 48시간-$EC_{50}$은 2,889.56mg/L (95% 신뢰한계는 1,073.407~6,854.321 mg/L), 무영향농도는 1,000 mg/L이었다. 처리기간 중 해충저항성 Bt벼와 낙동벼간의 급성독성에 영향을 미칠 수 있는 요인은 발생하지 않았다.