Introduction of Bacillus thuringiensis (Bt) gene does not reduce potassium use efficiency of Bt transgenic cotton (Gossypium hirsutum L.)

Abstract Background Potassium (K) deficiency has become a common field production problem following the widespread adoption of Bacillus thuringiensis (Bt) transgenic cotton (Gossypium hirsutum L.) worldwide. The purpose of this study was to clarify whether the introduction of Bt gene directly reduces the K-use efficiency of cotton to induce K deficiency. Results The cotton variety, Jihe 321 (wild type, WT) and its two Bt (Cry1Ac)-transgenic overexpression lines (OE-29317, OE-29312) were studied in field with low soil-test K+ (47.8 mg·kg−1). In the field with low soil-test K+, only OE-29317 had less biomass and K+ accumulation than the WT at some growth stages. Both Bt lines produced similar or even greater seed cotton yield than WT in the field. When the Bt gene (~ 70%) in OE-29317 and OE-29312 plants was silenced by virus-induced gene silencing (VIGS), the VIGS-Bt plants did not produce more biomass than VIGS-green fluorescent protein (control) plants. Conclusions The introduction of Bt gene did not necessarily hinder the K use efficiency of the cotton lines under this study.