Mechanisms of Pathogenicity and Host Specificity of the Oomycete Plant Pathogen Phytophthora palmivora

卵菌类植物病原棕榈疫霉的致病机制和寄主特异性

• 批准号: 2303713
• 负责人: Miaoying Tian
• 金额: $ 22.5万
• 依托单位: University of Hawaii
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-08-01 至 2024-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2303713&HistoricalAwards=false
• 关键词: Mechanisms; Pathogenicity; Host; Specificity; Oomycete

Phytophthora palmivora is a fungus-like eukaryotic microorganism that causes devastating diseases of numerous agriculturally and ecologically important plants, including cacao, a tropical perennial tree that produces the major component of the multi-billion-dollar chocolate industry. The annual global loss on cacao due to diseases caused by P. palmivora is at least one billion U.S. dollars. As a very aggressive pathogen, P. palmivora is often capable of infecting almost all plant parts of a host, rendering its control extremely challenging. As a result, it has become an increasing threat to agricultural production and ecosystems. Diseases caused by P. palmivora are managed by frequent application of fungicides with limited success. The long-term goal of this project is to develop novel, effective and environmentally friendly strategies to control P. palmivora based on the fundamental understandings of its infection mechanisms. To this end, the specific objectives of this project are to identify the key pathogenicity factors of P. palmivora, how these factors act on plant cellular components to contribute to disease, and how their presence/absence in a P. palmivora isolate determines which plant species to infect. This project is expected to generate significant foundational knowledge essential for developing desirable disease control measures, thereby significantly contributing to food security, sustainability of natural ecosystems and the bioeconomy. In addition, the project will contribute to STEM workforce sustainability by providing training opportunities to graduate, undergraduate and high school students, and introducing plant pathology and gene-editing technology to middle/high-school teachers to attract a new generation into agriculture and life sciences. Oomycetes form a distinct phylogenetic lineage of eukaryotes, with many causing devastating diseases of plants and animals. Phytophthora palmivora is a destructive broad-host-range oomycete plant pathogen with host specificity. P. palmivora delivers a diverse array of effectors to manipulate the host cellular processes to facilitate infection, including the superfamily of RxLR effectors that are defined by an N-terminal signal peptide followed by a canonical RxLR (or RxLR-EER) translocation motif that mediates entry into host cells. The P. palmivora RxLR effector designated PpalRxLR1 contains a functional nuclear localization signal with potential DNA-binding activities and was identified as a key pathogenicity factor on cacao. It is present in all examined P. palmivora isolates obtained from cacao infections, but exhibits presence/absence polymorphisms across the species, suggesting that it may be a determinant of host range and specificity. This project is to: 1) determine the mechanisms by which PpalRxLR1 confers pathogenicity on cacao by determining its nuclear-localized molecular interaction dynamics and the subverted host cellular processes during infection, 2) determine the role of PpalRxLR1 as a key component in host range evolution of P. palmivora by analyzing its evolution relative to the species and association with host range, 3) identify additional effectors with key roles in pathogenicity of P. palmivora on specific or a broad range of hosts using the natural variation of P. palmivora isolates. Integrating across specific aims is expected to transform understanding of the molecular basis of pathogenicity and host range evolution of P. palmivora, key aspects of plant-microbe interactions.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

棕榈疫霉（Phytophthora palmivora）是一种真菌样真核微生物，可导致许多农业和生态重要植物的毁灭性疾病，包括可可，一种热带多年生树木，生产数十亿美元巧克力工业的主要组成部分。棕榈芽孢杆菌引起的疾病每年给全球可可造成至少10亿美元的损失。作为一种极具侵袭性的病原体，掌叶假单胞菌通常能够感染宿主的几乎所有植物部位，使其控制极具挑战性。因此，它已成为对农业生产和生态系统日益严重的威胁。棕榈芽孢杆菌引起的疾病是通过频繁使用杀菌剂来控制的，但效果有限。本项目的长期目标是基于对棕榈芽孢杆菌感染机制的基本认识，开发新的、有效的、环境友好的防治策略。为此，该项目的具体目标是确定掌叶假单胞菌的关键致病因子，这些因子如何作用于植物细胞成分从而导致疾病，以及它们在掌叶假单胞菌分离物中的存在/不存在如何决定感染哪些植物物种。预计该项目将产生对制定理想的疾病控制措施至关重要的重要基础知识，从而为粮食安全、自然生态系统的可持续性和生物经济作出重大贡献。此外，该项目将为研究生、本科生和高中生提供培训机会，并向中学/高中教师介绍植物病理学和基因编辑技术，以吸引新一代进入农业和生命科学领域，从而促进STEM劳动力的可持续发展。卵菌形成了真核生物的一个独特的系统发育谱系，许多卵菌引起了植物和动物的毁灭性疾病。棕榈疫霉（Phytophthora palmivora）是一种具有寄主特异性的广谱破坏性卵菌植物病原体。palmivora提供多种效应物来操纵宿主细胞过程以促进感染，包括RxLR效应物超家族，该效应物由n端信号肽定义，随后是一个规范的RxLR（或RxLR- eer）易位基序，介导进入宿主细胞。palmmivora RxLR效应物PpalRxLR1含有一个具有潜在dna结合活性的功能性核定位信号，被鉴定为可可的关键致病因子。它存在于所有从可可感染中获得的棕榈芽孢杆菌分离株中，但在整个物种中表现出存在/不存在多态性，这表明它可能是宿主范围和特异性的决定因素。本项目旨在：1)通过测定其核定位分子相互作用动力学和侵染过程中破坏宿主细胞过程，确定PpalRxLR1对可可致病性的作用机制；2)通过分析PpalRxLR1的种间进化及与宿主范围的关联，确定PpalRxLR1在棕榈叶疟原虫宿主范围进化中的关键作用；3)利用棕榈芽孢杆菌分离物的自然变异，确定在棕榈芽孢杆菌对特定或广泛宿主致病性中起关键作用的其他效应物。跨特定目标的整合有望改变对棕榈芽孢杆菌致病性的分子基础和寄主范围进化的理解，以及植物与微生物相互作用的关键方面。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。