Collaborative Research: Investigating the development and treatment of plant diseases caused by the bacterium Xylella fastidiosa using theoretical and experimental methods

苛养木杆菌（Xylella fastidiosa，Xf）是一种能在葡萄、柑橘、桃和蓝莓等作物中引起毁灭性植物病害的细菌。 本项目的目标是了解的进展和处理木质部污染的细菌生物膜形成的植物病原体Xf使用紧密耦合的理论和实验技术。 为该项目开发的核心数学模型使用多阶段方法，这是一个灵活的框架，可以解释疾病进展过程中发生的复杂相互作用。 多相建模是一个自然的框架，以解释规模的巨大变化（从细菌规模到通道长度规模）。 材料从自由游动的细菌转移到生物膜结合的细菌以及生物质（细菌和细胞外聚合物“胶”）的产生需要区分系统内的材料类型。 最后，多相模型本质上是守恒定律的陈述，为结合物理和化学过程提供了一种相对简单的方法。 在实验上，使用微流体技术研究细菌细胞的特定行为被认为是新发现的有用工具。 在受控条件下对单个细菌细胞的研究导致了对细菌生长及其与微生物之间关系的新认识。 De La Fuente的实验室开发了微流控室，作为研究维管植物细菌病原体感染过程的一种新技术方法，其特定目标是确定植物感染的主要症状（如叶片烧焦）是否是由于生物膜堵塞水运输网络导致的水通量减少，或者是否也涉及植物的主动反应。 此外，调查将侧重于治疗这种疾病的非破坏性方法。 这两个目标提供了对疾病过程和治疗的基本见解。 理论（数学）和实验（生物）方法之间的合作用于验证数学理论，并提出疾病治疗的新途径。 该项目最初使用实验数据来验证理论建模。 反过来，建模和分析用于测试在实验室中难以测试的关于疾病发展的各种假设（例如，闭塞与植物反应）。 此外，理论预测指向特定的实验设计（例如治疗方案），可以提供有价值的洞察到非破坏性疾病治疗。

Xylella fastidiosa (Xf) is a bacterium that causes devastating plant diseases in crops such as grapes, citrus, peaches and blueberries. The goal of this project is to understand the progression and treatment of xylem fouling by bacterial biofilms formed by the plant pathogen Xf using tightly coupled theoretical and experimental techniques. The core mathematical model developed for the project uses a multiphase approach that is a flexible framework accounting for the complex interactions occurring during the disease progression. Multiphase modeling is a natural framework to account for the dramatic variation in scales (from the bacterial scale to the channel length scale). The transfer of material from free-swimming bacteria to biofilm-bound bacteria and the production of biomass (bacteria and extra-cellular polymeric 'glue') requires a distinction between the types of material within the system. Finally, multiphase models are essentially statements of conservation laws providing a relatively simple method for incorporating physical and chemical processes. Experimentally, the use of microfluidics for studies of specific behaviors of bacterial cells is recognized as a useful tool for new discoveries. Studies on single bacterial cells under controlled conditions are leading to new understandings of bacterial growth and relationship with the. Microfluidic chambers have been developed by De La Fuente's lab as a new technological approach to study the infection process of vascular plant bacterial pathogens.The particular objectives are to determine whether the dominant symptoms of the plant infection, such as leaf scorch, are due to reduced water flux caused by occlusion of the water transport network by the biofilm or whether active plant responses are also implicated. Further, the investigation will focus on non-destructive methods of treatment of the disease. These two objectives provide fundamental insight into the disease process and treatment. The collaboration between the theoretical (mathematics) and experimental (biological) methods are used to validate the mathematical theory and suggest new avenues of disease treatment. The project initially uses experimental data to validate the theoretical modeling. In turn, the modeling and analysis is used to test various hypotheses on the disease development (e.g. occlusion versus plant responses) that are difficult to test in the laboratory. In addition, the theoretical predictions point to particular experimental designs (e.g. treatment regimes) that may provide valuable insight into non-destructive disease treatment.