Bioscience Evidence 2025, Vol.15, No.6, 303-312 http://bioscipublisher.com/index.php/be 306 defense. To address such issues, researchers began to superimpose multiple R genes that recognize effectors of different pathogenic bacteria onto the same potato variety. Multi-gene superposition can make resistance broader and more persistent because pathogenic bacteria must simultaneously break through multiple recognition systems to cause disease, which greatly increases the difficulty of breaking through resistance. Genetic engineering is faster and more effective, that is, directly introducing multiple R genes from wild potato varieties into superior varieties. The researchers introduced Rpi-vnt1.1 fromSolanum venturii, Rpi-blb3 fromS. bulbocastanum, and Rpi-chc1 fromS. chacoense into the highly susceptible variety Desiree together. Obtain a transgenic line capable of expressing three genes. Researchers will use specific molecular markers and effector detection methods to confirm whether each gene is functioning properly. These materials superimposed with multiple R genes will enter field trials to detect their performance in real disease environments. 4.2 Resistance evaluation under different pathogenic bacterial populations The key to evaluating the effectiveness of multi-R gene superposition lies in whether they can maintain resistance in different regions and different types of P. infestans populations. Relevant field trials were carried out in multiple regions, including areas with high genetic diversity and the presence of dominant pathogenic clones. In these experiments, transgenic potato materials carrying two or three R genes showed stable resistance to a variety of P. infestans isolates, including those highly virulent strains capable of breaking through the defense of a single R gene (Ghislain et al., 2018; Byarugaba et al., 2021) (Figure 1). In field trials conducted in the Netherlands, Belgium and sub-Saharan Africa, the materials superimposed with Rpi-vnt1.1, Rpi-blb3 and Rpi-sto1 demonstrated strong resistance in multiple seasons and at various locations. These materials not only have a wide range of resistance but also are more durable. Even when facing local pathogenic bacteria with the ability to break through single-gene, no "resistance failure" has occurred. Figure 1 Confined field trial 60 days after planting during the second season (Oct 14, 2015-Jan 20, 2016) with a close-up on nontransgenic ‘Victoria’ plant heavily infected byPhytophthora infestans (Adopted from Ghislain et al., 2018) 4.3 ‘Complete resistance’ was observed under field conditions The transgenic material carrying three R genes did not show any lesions or symptoms throughout the entire growth period. In multi-seasonal field trials in Uganda, transgenic materials (containing RB, Rpi-blb2, and
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