Xanthomonas citri subsp citri citrus tree cankers in Sao Paulo : molecular epidemiology and assessment of lytic bacteriophage as biocontrol agents

点击翻译按钮获取中文摘要

Asiatic Citrus Canker (ACC) is a serious, untreatable infection of citrus trees that threatens sweet orange production in the state of Sao Paulo - a key industry economically. ACC is caused by the bacterium Xanthomonas citri subsp. citri. Infection with this organism necessitates removal and destruction of infected trees and prevention measures typically rely on the use of spraying with environmentally harmful copper bactericides. In this project we will examine the current genetic diversity and molecular epidemiology of X. citri from infected plants in Sao Paulo using whole genome sequencing. This will allow us to study how the pathogen is spreading in the current endemic situation - following legislative changes that ceased control efforts and now allow the presence of the bacterium in the orchards. This information will give us important new knowledge regarding the species population biology. In this project we will also isolate and characterize X. citri specific viruses (known as bacteriophage). Bacteriophages are proposed as an alternative to antibiotics in human health and they are currently used in the food industry eg for controlling Listeria contamination in cheese production. They are also used in the control of bacterial infections in tomato and pepper crops in the United States. We will isolate and characterize a large collection of bacteriophage from infected plant material to assess their suitability for use in biocontrol of ACC. This initial pump-priming proposal will be developed in years two and three to include in vitro infection studies in greenhouse using bacteriophages as treatments or protective agents. We will also investigate bacteriophage host-binding structures as possible species-specific ligands for delivery of antimicrobial compounds.