Agrobacterium is commonly used in plant engineering to insert DNA into plant chromosomes. In this study, a unique insertion of DNA was found at the BRI1 gene in Arabidopsis thaliana. This insertion, named juicebox, involved not only T-DNA but also a transposon from bacteria. The insertion caused a deletion of a region on the plant chromosome, including important genes like BRI1 and WRKY13. This discovery shows that T-DNA insertions can have unexpected effects on plant genomes, leading to mutations.