Cry1Ba1-mediated toxicity of transgenic and to the Asian citrus psyllid .

The Asian citrus psyllid, , vectors the bacterial causative agent of citrus greening disease, which has severely impacted citrus production on a global scale. As the current repeated application of chemical insecticides is unsustainable for management of this insect and subsequent protection of groves, we investigated the potential use of the bacteria-derived pesticidal protein, Cry1Ba1, when delivered transgenic citrus plants. Having demonstrated transformation of the Indian curry leaf tree, , for Cry1Ba1 expression for use as a trap plant, we produced transgenic plants of Duncan grapefruit, , Valencia sweet orange, , and Carrizo citrange, , for expression of Cry1Ba1. The presence of the gene, and transcription were confirmed. Western blot detection of Cry1Ba1 was confirmed in most cases. When compared to those from wild-type plants, leaf discs from transgenic Duncan and Valencia expressing Cry1Ba1 exhibited a "delayed senescence" phenotype, similar to observations made for transgenic . In bioassays, significant reductions in the survival of adult psyllids were noted on transgenic and Valencia sweet orange plants expressing Cry1Ba1, but not on transgenic Duncan grapefruit or Carrizo citrange. In contrast to psyllids fed on wild type plants, the gut epithelium of psyllids fed on transgenic plants was damaged, consistent with the mode of action of Cry1Ba1. These results indicate that the transgenic expression of a bacterial pesticidal protein in and Valencia sweet orange offers a viable option for management of , that may contribute to solutions that counter citrus greening disease.