Tancos Matthew A, Sechler Aaron J, Davis Edward W, Chang Jeff H, Schroeder Brenda K, Murray Timothy D, Rogers Elizabeth E
Foreign Disease-Weed Science Research Unit, United States Department of Agriculture-Agricultural Research Service, Frederick, MD, United States.
Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, United States.
Front Microbiol. 2020 Jan 10;10:2914. doi: 10.3389/fmicb.2019.02914. eCollection 2019.
Tunicaminyluracil antibiotics are a novel class of toxigenic glycolipids that are synthesized by several soil-associated . The acquisition of a tunicaminyluracil biosynthetic gene cluster (TGC) in has led to the emergence of the only described, naturally occurring tunicaminyluracil-associated mammalian disease, annual ryegrass toxicity of livestock. Endemic to Australia, is obligately vectored by Anguinid seed gall nematodes to the developing seedheads of forage grasses, in which the bacteria synthesize tunicaminyluracils that may subsequently be consumed by livestock and result in high rates of mortality and morbidity. The potential impact of on U.S. agriculture has led the U.S. Department of Agriculture - Animal and Plant Health Inspection Service to list as a Plant Pathogen Select Agent. is the only characterized phytopathogenic bacterium to produce tunicaminyluracils, but numerous -like livestock poisonings outside Australia suggest additional bacterial sources of tunicaminyluracils may exist. To investigate the conservation of the TGC in and whether the TGC is present in other species, we analyzed genome sequences of members of the genus. Putative TGCs were identified in genome sequences of , , and an undescribed South African species. In the latter three species, the putative TGCs have homologs of tunicaminyluracil-related genes essential for toxin production, but the TGCs differ in gene number and order. The TGCs appear at least partially functional because in contrast to atoxigenic species, TGC-containing species were each able to tolerate exogenous applications of tunicamycin from . The North American TGC shows extensive diversity among the sequenced isolates, with presense/absense polymorphisms in multiple genes or even the whole TGC. TGC structure does not appear to correlate with date or location of isolate collection. The conservation and identification of tunicaminyluracil-related gene clusters in three additional species isolated from South Africa, the Middle East, and the United States, suggests a wider global distribution of potentially neurotoxigenic plant-associated bacteria. This potential for additional endemic and exotic toxigenic species could have widespread and severe implications for agriculture.
甘露糖胺基尿嘧啶抗生素是一类新型的产毒糖脂，由几种与土壤相关的细菌合成。[某种细菌名称]中获得的甘露糖胺基尿嘧啶生物合成基因簇（TGC）导致了唯一已知的、自然发生的与甘露糖胺基尿嘧啶相关的哺乳动物疾病——家畜一年生黑麦草中毒的出现。该病在澳大利亚为地方病，通过环腐线虫专性传播到饲草发育中的穗头，细菌在其中合成甘露糖胺基尿嘧啶，随后家畜可能食用这些物质，导致高死亡率和发病率。[某种细菌名称]对美国农业的潜在影响已导致美国农业部动植物卫生检验局将其列为植物病原体选择剂。[某种细菌名称]是唯一已鉴定出的产生甘露糖胺基尿嘧啶的植物致病细菌，但澳大利亚以外众多类似[某种细菌名称]导致家畜中毒的情况表明，可能存在其他产生甘露糖胺基尿嘧啶的细菌来源。为了研究[某种细菌名称]中TGC的保守性以及TGC是否存在于其他[某种细菌名称]物种中，我们分析了[某种细菌名称]属成员的基因组序列。在[某种细菌名称]、[某种细菌名称]和一种未描述的南非[某种细菌名称]物种的基因组序列中鉴定出了推定的TGC。在后三个物种中，推定的TGC具有毒素产生所必需的甘露糖胺基尿嘧啶相关基因的同源物，但TGC在基因数量和顺序上有所不同。这些TGC似乎至少部分具有功能，因为与无毒菌株相比，含有TGC的[某种细菌名称]物种均能够耐受来自[某种物质名称]的衣霉素的外源应用。北美[某种细菌名称]的TGC在测序分离株中表现出广泛的多样性，多个基因甚至整个TGC存在有无多态性。[某种细菌名称]TGC的结构似乎与分离株收集的日期或地点无关。从南非、中东和美国分离出的另外三个[某种细菌名称]物种中甘露糖胺基尿嘧啶相关基因簇的保守性和鉴定表明，潜在的神经产毒植物相关细菌在全球分布更广。这种额外的地方病和外来产毒[某种细菌名称]物种的可能性可能对农业产生广泛而严重的影响。
