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

亚洲柑橘溃疡病（ACC）是一种严重的、无法治愈的柑橘树感染，威胁着圣保罗州的甜橙生产，这是一个重要的经济产业。ACC是由柑橘黄单胞菌亚种引起的。citri。感染这种生物需要清除和摧毁受感染的树木，预防措施通常依赖于使用对环境有害的铜杀菌剂喷洒。在本项目中，我们将利用全基因组测序技术研究圣保罗受感染植株中柑橘X. citri的遗传多样性和分子流行病学。这将使我们能够研究病原体是如何在目前的地方病情况下传播的——在立法改变后，控制工作停止了，现在允许细菌在果园中存在。这些信息将为我们提供有关物种种群生物学的重要新知识。在这个项目中，我们还将分离和表征柑橘X.特异性病毒（称为噬菌体）。噬菌体被认为是人类健康中抗生素的替代品，目前它们被用于食品工业，例如控制奶酪生产中的李斯特菌污染。在美国，它们也被用于控制番茄和辣椒作物的细菌感染。我们将从受感染的植物材料中分离和鉴定大量噬菌体，以评估它们在ACC生物防治中的适用性。这个最初的泵启动建议将在第二年和第三年发展，包括在温室中使用噬菌体作为治疗或保护剂的体外感染研究。我们还将研究噬菌体宿主结合结构作为递送抗菌化合物的可能的物种特异性配体。

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.