Evaluation of transgenic cotton lines expressing an insecticidal fern protein against whitefly, Bemisia tabaci (Gennadius)

Abstract Background Transgenic research in crops involves using genetic engineering techniques to introduce specific genes of interest from other organisms, or even entirely new genes into plant genomes to create crops with desirable traits that wouldn't be possible through conventional breeding methods. Transgenic crops have been developed for various traits globally. Whitefly, Bemisia tabaci (Gennadius) is one of the major sucking pests of cotton that cause significant damage to the cotton production. To combat whitefly infestations, researchers have developed four transgenic cotton lines expressing the fern protein. And those transgenic lines need to be evaluated for their performance against the target pest—whitefly. The evaluation was designed as controlled trials in polyhouse or muslin cloth cages under open-choice and no-choice conditions by comparing four transgenic cotton lines (A, B, C, and D) with three control groups, including untransformed cotton plants with a same genetic background of the transgenic line, conventionally bred whitefly-resistant cotton, and whitefly-susceptible cotton. In order to study the generational effect, the evaluation also involved studies on whitefly development in laboratory, muslin cloth cage, and polyhouse conditions. Results Both open-choice and no-choice experiments had shown that all the four transgenic cotton lines (A, B, C, and D) expressing the fern protein reduced adult whitefly numbers significantly compared with the control lines, except for the no-choice conditions in 2021, where the transgenic line C was non-significant different from the resistant control line. Notably, the nymphal population on the resistant control line was relatively low and non-significant different from the transgenic line C in 2021; and the transgenic lines A and C in 2022 under open-choice conditions. Under no-choice condition, the nymphal counts in the resistant control line was non-significant different from transgenic lines C and D in 2021; and transgenic line D in 2022. All transgenic lines showed significant decrease in egg hatching in 2021 and nymphal development in 2022, except for the transgenic line C which had no significant different in the nymphal development comparing with non-transgenic control lines in 2022. Adult emergence rates in both years of evaluation showed significant decrease in transgenic lines A and B comparing with the control lines. Additionally, the results showed a significant reduction in cotton leaf curl disease and sooty mold development in all the four transgenic lines compared with susceptible control under open-choice conditions, indicating potential benefits of transgenic lines beyond direct effect on whitefly control. Furthermore, the research explored the generational effects of the fern protein on whitefly which revealed the lowest fecundity in the transgenic line C across F 0 , F 1 and F 3 generations, lower egg hatching in F 1 and F 2 generations in transgenic lines A and B, shorter nymphal duration in F 1 and F 2 generations in transgenic line B, and the least total adult emergence in the transgenic line C in F 0 and F 3 generations. Conclusions These findings suggest that the transgenic cotton lines expressing fern protein disrupts whitefly populations and the life cycle to a certain extent. However, results are not consistent over generations and years of study, indicating these transgenic lines were not superior over control lines and need to be improved in future breeding.