Transgenic Bt (Cry1Ab/Ac) rice lines with different genetic backgrounds exhibit superior field performance under pesticide-free environment

Transgenic rice with Cry Bacillus thuringiensis (Bt) genes have been developed in the last few decades. The performance of transgenic rice, especially the yield and resistance, must be meticulously evaluated prior to commercial production. In this study, yield and resistance performance of newly bred transgenic Bt (Cry1Ab/Ac) rice lines with different genetic backgrounds were first investigated under pesticide-free field environment. Transgenic Bt (Cry1Ab/Ac) rice lines showed high insect resistances and superior agronomic traits, resulting in obvious yield advantages ranging from 9.1% to 38.0% over their respective non-Bt control lines. Bt protein content (BTC) was similar among the Bt (Cry1Ab/Ac) rice lines in different years, while it was much higher in leaves than in stems of the Bt (Cry1Ab/Ac) rice lines. Different genetic backgrounds of Bt (Cry1Ab/Ac) rice lines affected the yield advantage but had no influence on the resistance and BTC. The results suggested that Bt (Cry1Ab/Ac) rice lines have gained obvious yield advantages and high resistances regardless of genetic background under pesticide-free environment.