Transgenic Bt rice lines producing Cry1Ac, Cry2Aa or Cry1Ca have no detrimental effects on Brown Planthopper and Pond Wolf Spider

Lin Niu,Juan Luis Jurat-Fuentes,Weihua Ma,Chaoliang Lei,Xiaoping Wang,Hongxia Hua,Amani Mannakkara,Lin Qiu

doi:10.1038/s41598-017-02207-z

Lin Niu, Juan Luis Jurat-Fuentes + Show 6 more

Open Access

https://doi.org/10.1038/s41598-017-02207-z

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Abstract

Transgenic rice expressing cry genes from the bacterium Bacillus thuringiensis (Bt rice) is highly resistant to lepidopteran pests. The brown planthopper (BPH, Nilaparvata lugens) is the main non-target sap-sucking insect pest of Bt transgenic rice. The pond wolf spider (PWS, Pardosa pseudoannulata) is one of the most dominant predators of BPH in rice fields. Consequently, the safety evaluation of Bt rice on BPH and PWS should be conducted before commercialization. In the current study, two experiments were performed to assess the potential ecological effects of Bt rice on BPH and PWS: (1) a tritrophic experiment to evaluate the transmission of Cry1Ac, Cry2Aa and Cry1Ca protein in the food chain; and (2) binding assays of Cry1Ac, Cry2Aa and Cry1Ca to midgut brush border membrane proteins from BPH and PWS. Trace amounts of the three Cry proteins were detected in BPH feeding on Bt rice cultivars, but only Cry1Ac and Cry2Aa proteins could be transferred to PWS through feeding on BPH. In vitro binding of biotinylated Cry proteins and competition assays in midgut protein vesicles showed weak binding, and ligand blot analysis confirmed the binding specificity. Thus, we inferred that the tested Bt rice varieties have negligible effects on BPH and PWS.

Highlights

The brown planthopper (BPH, Nilaparvata lugens Stål) (Hemiptera: Delphacidae) is found in most rice fields worldwide[17, 18]
No Cry proteins were detected in the BPH reared on non-transgenic rice isoline (MH 63)
No Cry proteins were detected in the PWS predating on BPH fed the non-transgenic rice isoline (MH 63)

Summary

Introduction

The brown planthopper (BPH, Nilaparvata lugens Stål) (Hemiptera: Delphacidae) is found in most rice fields worldwide[17, 18]. When supplied with Bt rice-fed BPH, the Cry1Ab protein was detected in Ummeliata insecticeps, but no effects on its survival and development were observed[33]. Despite these previous reports, very few studies have detected the binding of the Cry protein in the predator spider[34], and the Cry binding protein in PWS is still unknown. We used three transgenic Bt rice lines producing Cry1Ab/1Ac fused proteins, Cry2Aa or Cry1Ca proteins to investigate the effects of Bt toxins on the non-target insect BPH and its predator PWS. The work reported here had 2 objectives: (1) to quantify the Cry proteins in both BPH after being fed on Bt rice and in PWS after feeding on BPH that had been reared on Bt rice; (2) to evaluate the binding of the three Cry proteins (Cry1Ac, Cry2Aa and Cry1Ca) produced by the rice lines in midgut brush border membrane vesicles (BBMVs) from BPH and PWS

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Conclusion