Molecular mechanisms involved in pathogen adaptation and virulence, host resistance and symptom development in citrus-bacteria interactions

• Grant number: 11/20468-1
• Support type: Research Projects - Thematic Grants
• Duration: July 01, 2012 - June 30, 2018
• Field of knowledge: Biological Sciences - Biochemistry
• Principal Investigator: Celso Eduardo Benedetti
• Grantee: Celso Eduardo Benedetti
• Home Institution: Centro Nacional de Pesquisa em Energia e Materiais (CNPEM). Associação Brasileira de Tecnologia de Luz Síncrotron (ABTLuS). Ministério da Ciência, Tecnologia, Inovações e Comunicações (Brasil). Campinas, SP, Brazil
• Co-Principal Investigators: Andrea Balan
• Assoc. researchers: Adriana Franco Paes Leme ; Ana Carolina de Mattos Zeri ; Andre Luis Berteli Ambrosio ; Juliana Helena Costa Smetana ; Marcelo Falsarella Carazzolle ; Maria Luiza Peixoto de Oliveira ; Mário Tyago Murakami ; Maurício Luís Sforça ; Paulo Sergio Lopes de Oliveira
• Associated scholarship(s): 17/18570-9 - Functional analysis of CsMAF1, an RNA polymerase iii repressor involved in cell growth control and pathogen response in plants, BP.PD; 17/07641-2 - Synthesis and characterization of inhibitors for human and citrus deadenylase CAF1 (CNOT7), BP.IC; 16/03151-8 - Aminoacil-tRNA synthetases as targets for development of Agrobactericides intented for control of plant diseases caused by Xanthomonas species, BP.PD; + associated scholarships 15/18712-2 - Functional and structural studies of the repressor protein phoU in the phosphate transport signalling in Xanthomonas axonopodis pv. citri, BP.MS; 14/19623-0 - Functional analysis of the cyclophilin CsCyp on citrus genes transcription activated by tal effectors from Xanthomonas citri, BP.PD; 13/22399-2 - Biochemical and functional analysis of a citrus sinensis protein, CsEIE, involved in the defense against Xanthomonas citri, BP.DD; 13/24043-0 - Functional analysis of the bigR operon from Xylella fastidiosa: identification of inhibitor molecules for the sulfur dioxygenase Blh and possible redox mechanism involved in BigR oxidation and operon activatio, BP.DR; 13/22507-0 - Functional characterization of CsWRKY, a sweet orange (citrus sinensis) transcription factor involved in citrus canker resistance, BP.PD - associated scholarships

Abstract

The citrus industry is one of the most important agribusiness sectors in Brazil benefiting not only the citrus growers, exporters and consumers, but the society in general with incomes and jobs. However, despite its economic strength, the sector is facing several challenges and production costs have risen annually due mostly to the need of controlling numerous citrus diseases with agrochemicals and pesticides. We have been studying the interaction of citrus plants with the bacterial pathogens Xanthomonas citri and Xylella fastidiosa, the causal agents of "citrus canker" and "citrus variegated chlorosis", respectively. Previously, we identified several sweet orange proteins involved in the recognition of the so called transcriptional-activator like (TAL) effectors from X. citri, and X. fastidiosa proteins required for bacterial growth under low oxygen tension. In addition, we found that the plant hormones auxin and gibberellin are required for initial canker development and that TAL effectors from Xanthomonas aurantifolii pathotype C, a pathogen of the Mexican lime only, appears to function as "Avr" proteins in sweet oranges. In this proposal, we plan to elucidate the function of various X. citri and X. aurantifolii TAL effectors as pathogenicity and/or avirulence factors, and characterize the function of particular ABC transporter systems expected to play a role in pathogen adaptation. Moreover, we plan to elucidate the structure and function of sweet orange proteins implicated in canker development and resistance responses against X. aurantifolii and to generate transgenic citrus plants with increased resistance against bacterial pathogens, particularly X. citri. The proposal will also include an approach to obtain citrus plants resistant to Candidatus liberibacter, the causal agent of "Huanglongbing". (AU)