Genetically modified citrus suppressing Diffusible Signaling Factor (DSF): influence on the acquisition and transmission of Xylella fastidiosa by the vector insect and translocation of the rootstock to the scion

• Grant number: 20/08287-0
• Support Opportunities: Scholarships in Brazil - Post-Doctorate
• Effective date (Start): June 01, 2022
• Effective date (End): May 31, 2024
• Field of knowledge: Agronomical Sciences - Agronomy - Plant Health
• Principal Investigator: Alessandra Alves de Souza
• Grantee: Mariana Bossi Esteves
• Host Institution: Instituto Agronômico (IAC). Agência Paulista de Tecnologia dos Agronegócios (APTA). Secretaria de Agricultura e Abastecimento (São Paulo - Estado). Campinas , SP, Brazil
• Associated research grant: 13/10957-0 - Xylella fastidiosa-vector-host plant interaction and approaches for citrus variegated chlorosis and citrus canker control, AP.TEM

Abstract

The bacterium Xylella fastidiosa, which causes several diseases in crops of economic interest, has a complex lifestyle. To be successfully transmitted, in addition to colonizing the host plant xylem it must also colonize the foregut of the insect vectors, which are sharpshooters of the subfamily Cicadellinae (Hemiptera: Cicadellidae) and superfamily Cercopoidea. Colonization in both is regulated by a Quorum Sensing (QS) system, which allows bacterial cells to regulate the activation and repression of genes linked to the pathogenic mechanism. The best-known QS molecules in X. fastidiosa are the diffusible signaling factor (DSF). Previous studies by our research group have developed Genetically Modified (GM) plants of two commercial sweet orange varieties that synthesize DSF. These plants when inoculated with X. fastidiosa and X. citri showed a significant reduction in the symptoms of the disease, due to a more adherent phenotype of the bacterium and its difficulty in moving and in the host plant. GM sweet orange plants are being tested in the field with the proper authorization from LPMA by CTNBio. However, it is not yet known about the influence of DSF overproduction in relation to the interaction with the insect vector in these plants. The knowledge of this interaction will be the object of study of this postdoctoral project. Another aspect that will be addressed in this project is the use of GM rootstocks with non-GM varieties of canopy, as an alternative to the non-acceptance of GM fruits by the consumer. In this context, the present postdoctoral work aims to: I) to evaluate the influence of the overproduction of DSF by the GM plant on the feeding behavior of the insect vector, as well as on the acquisition and transmission of X. fastidiosa; II) rooting rootstocks of the swingle variety already transformed with the rpfF gene, which encodes the protein responsible for the production of DSF, grafting scions of commercial variety of sweet orange and assess resistance to X. fastidiosa and X. citri and; III) build biosensors to detect DSF molecules being translocated from the rootstock to the non-transgenic scion. (AU)