Dynamic mini-chromosomes: mechanisms of exchange, stability and causation of fungal pathogen adaptation

动态微型染色体：交换机制、稳定性和真菌病原体适应的因果关系

• 批准号: 2011500
• 负责人: Sanzhen Liu
• 金额: $ 60万
• 依托单位: Kansas State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-07-01 至 2025-06-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2011500&HistoricalAwards=false
• 关键词: Dynamic; mini; chromosomes; mechanisms; exchange

Food crops are constantly threatened by new variants of established pathogens and by newly-emerged pathogens. The rice blast fungus Magnaporthe oryzae has a long history of variation to overcome resistance deployed in rice crops, and a new M. oryzae variant emerged in 1985 to cause devastating disease on wheat in Brazil. Wheat blast disease is proving even harder to control than rice blast because potential resistance genes identified using strains from the 1980s are no longer effective in controlling recent aggressive isolates. Global spread of the disease and lack of control measures enhance fears about global food security. Recent studies indicated that dispensable supernumerary chromosomes from blast field isolates might accelerate adaptive evolution and contribute to virulence of the fungus. Supernumerary chromosomes are hypothesized to play roles in the evolution of pathogen genes that are critical for resistance in host plants, including host specificity at the plant species/genus and the crop cultivar levels. The project will study supernumerary chromosomes to understand their prevalence, movement between strains, DNA exchange with core-chromosomes, stability, and contributions to pathogenicity and virulence. Outcomes will be valuable for understanding genomic dynamics of the blast pathogen and help reveal roles of supernumerary chromosomes in many plants, animals and other fungi. Graduate students and undergraduates will receive broad training in genomics, bioinformatics, molecular plant-microbe interactions, and plant biosecurity. Undergraduates will participate in an 8-week summer research experience in plant disease diagnostics involving collections in the field and identification of disease organisms using cutting edge sequencing technologies. The fungus Magnaporthe oryzae causes blast diseases on more than 50 grass species, which include the ancient rice blast and the newly emerged wheat blast. Global agricultural threats posed by blast diseases and evolving pathogens make it important to understand genome dynamics of blast pathogens. The blast fungal genome includes hundreds of putative effector genes that are specifically expressed during host invasion and that generally encode small secreted proteins involved promoting disease. A subset of these effectors is recognized by host resistance gene products, which triggers resistance and blocks infection of that host. Such effectors play a major role in determining host specificity in blast fungal pathogens, both at the host species/genus level, and at the crop cultivar level. The recent genomic data of dispensable supernumerary chromosomes from the wheat blast field isolates showed that the supernumerary chromosomes contain many effector genes that are often found on indispensable core-chromosomes in other strains, as well as other genes that may play a role in pathogen aggressiveness. This project proposes to further understand supernumerary chromosomes with respect to their prevalence, inter-strain movement, DNA exchange with core-chromosomes, stability, and contributions to pathogenicity and virulence. The hypothesis will be tested that supernumerary chromosomes play roles in effector mobility by serving as a repository for effector genes that are deleted from core-chromosomes, and a role in mediating their relocation on core-chromosomes. The project will combine methodologies in blast disease biology, including adaptive evolution strategies, parasexual transfer between fungal strains, molecular biology, genomics, and cytology.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.

粮食作物不断受到既有病原体新变种和新出现病原体的威胁。稻瘟病菌Magnaporthe Magnaporthe在克服水稻抗性方面有着悠久的变异历史。1985年，巴西出现了一种对小麦造成毁灭性疾病的变种。事实证明，小麦稻瘟病比水稻稻瘟病更难控制，因为使用20世纪80年代的菌株鉴定的潜在抗性基因不再有效控制最近的侵略性菌株。该疾病的全球传播和缺乏控制措施加剧了人们对全球粮食安全的担忧。近年来的研究表明，稻瘟病菌田间分离物中的多馀染色体可能加速了适应性进化，并对致病性有贡献。推测额外染色体在病原体基因的进化中发挥作用，所述病原体基因对宿主植物的抗性至关重要，包括在植物种/属和作物栽培品种水平上的宿主特异性。该项目将研究额外染色体，以了解它们的流行，菌株之间的运动，与核心染色体的DNA交换，稳定性以及对致病性和毒性的贡献。研究结果对于了解稻瘟病病原体的基因组动态和揭示植物、动物和其他真菌中额外染色体的作用具有重要意义。研究生和本科生将接受基因组学，生物信息学，分子植物微生物相互作用和植物生物安全方面的广泛培训。本科生将参加为期8周的植物疾病诊断夏季研究经验，涉及在现场收集和使用尖端测序技术鉴定疾病生物。稻瘟病菌（Magnaporthe）在50多种草上引起稻瘟病，其中包括古老的稻瘟病和新出现的小麦稻瘟病。稻瘟病和不断进化的病原体对全球农业构成威胁，因此了解稻瘟病病原体的基因组动态非常重要。稻瘟病真菌基因组包括数百个推定的效应基因，这些效应基因在宿主入侵期间特异性表达，并且通常编码参与促进疾病的小分泌蛋白。这些效应子的子集被宿主抗性基因产物识别，其触发抗性并阻断该宿主的感染。这些效应子在确定稻瘟病真菌病原体的宿主特异性方面发挥重要作用，无论是在宿主种/属水平，还是在作物栽培品种水平。最近的基因组数据显示，小麦稻瘟病田间分离物的多馀染色体含有许多效应基因，这些基因通常存在于其他菌株的不可缺少的核心染色体上，以及其他可能在病原体侵袭性中发挥作用的基因。该项目旨在进一步了解额外染色体的流行，菌株间运动，与核心染色体的DNA交换，稳定性以及对致病性和毒性的贡献。该假设将被测试，额外染色体作为一个仓库的效应基因被删除的核心染色体，并在调解其搬迁的核心染色体上的作用，在效应器的流动性中发挥作用。该项目将结合联合收割机方法在稻瘟病生物学，包括适应性进化策略，真菌菌株之间的准性转移，分子生物学，基因组学，和cytology.This奖项反映了NSF的法定使命，并已被认为是值得的支持，通过评估使用基金会的智力价值和更广泛的影响审查标准。

项目成果

Dynamic Genomes - Mechanisms and consequences of genomic diversity impacting plant-fungal interactions

• DOI: 10.1016/j.pmpp.2023.102006
• 发表时间: 2023-03
• 期刊: Physiological and Molecular Plant Pathology
• 影响因子: 2.7
• 作者: Jun Huang;Sanzhen Liu;D. Cook