Streptomyces bacteria: Antibiotic production in the wheat endosphere

链霉菌：小麦内圈的抗生素生产

• 批准号: BB/T015446/1
• 负责人: Matthew Hutchings
• 金额: $ 64.04万
• 依托单位: John Innes Centre
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2020
• 资助国家: 英国
• 起止时间: 2020 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FT015446%2F1
• 关键词: Streptomyces; bacteria; Antibiotic; production; wheat

Plants use photosynthesis to fix carbon dioxide from the air into glucose which they use as food. However, up to 40% of the carbon they fix is released into the soil from their roots and this appears to be a mechanism to attract beneficial bacteria from the surrounding soil. The bacteria use the root exudates as food and this helps the plants assemble a healthy microbiome. Some of these microbes protect the plants against disease and others help them get important nutrients from the soil. The root microbiome is therefore essential for plant health, but crop breeding over hundreds of years has selected traits such as bigger plants with more grain while perhaps neglecting the (unknown) effects on the microbiome. There is now growing interest in manipulating the microbiomes of crop plants such as wheat to make them more resistant to disease and to abiotic stresses like drought and salinity. Wheat is a staple crop for about 4 billion people and one of the most important crops in the world so increasing yields is essential if we are to support a growing world population. Our project focuses on a genus of soil bacteria called Streptomyces. The ~600 known species of Streptomyces make numerous secondary metabolites, and these account for half of all the known antibiotics. They are easy to isolate from soil but also form stable interactions with plant roots and can colonise the rhizosphere and endosphere of a wide range of different plants. We have found they are abundant inside wheat roots and that some strains can protect wheat against fungal diseases such as Take-all which can cause devastating crop losses. For one of these strains we have identified the molecules and genes responsible for this antifungal activity and shown it is increased two-fold when we add indole 3 acetic acid, a plant hormone present in wheat root exudates, to the growth medium. In this proposal we aim to look in more detail at the colonisation of wheat roots by soil dwelling, antibiotic-producing Streptomyces bacteria. We will sequence the genomes of 10 strains we have isolated from wheat plants which inhibit the take-all fungus on agar plates, identify the antifungals made by these strains and determine if they can protect wheat plants against take-all disease. We will also try to discover which molecules in wheat root exudates can feed these bacteria and switch on their production of secondary metabolites. Since Streptomyces bacteria form spores which can be dried and stored for long periods, we are interested in developing wheat seed coatings containing these spores so the bacteria grow into the roots of germinating wheat plants and protect them against disease. We will also test the role of the type VII secretion system in root colonisation by these strains since we have preliminary evidence that this system helps them outcompete other bacteria for wheat root colonisation. Our ultimate aim is to develop streptomycetes as seed coatings to protect wheat plants against fungal disease and to discover molecules from wheat root exudates that we can use to switch on secondary metabolite production in vitro because we know that 90% of the secondary metabolites they encode are not made under laboratory conditions. This could help us discover new and useful molecules from these bacteria.

植物利用光合作用将空气中的二氧化碳固定成葡萄糖作为食物。然而，它们固定的高达 40% 的碳从根部释放到土壤中，这似乎是吸引周围土壤中有益细菌的机制。细菌利用根部分泌物作为食物，这有助于植物组装健康的微生物组。其中一些微生物可以保护植物免受疾病侵害，另一些则帮助它们从土壤中获取重要的养分。因此，根部微生物组对于植物健康至关重要，但数百年来的作物育种选择了诸如具有更多谷物的更大植物等性状，同时可能忽略了对微生物组的（未知）影响。现在，人们越来越关注操纵小麦等作物的微生物组，使它们对疾病以及干旱和盐度等非生物胁迫具有更强的抵抗力。小麦是约 40 亿人的主要作物，也是世界上最重要的作物之一，因此如果我们要养活不断增长的世界人口，提高产量至关重要。我们的项目重点关注一种称为链霉菌的土壤细菌。约 600 种已知的链霉菌种类可产生大量次生代谢产物，这些代谢产物占所有已知抗生素的一半。它们很容易从土壤中分离出来，但也与植物根部形成稳定的相互作用，并且可以在多种不同植物的根际和内圈定殖。我们发现它们在小麦根部含量丰富，并且某些菌株可以保护小麦免受真菌病害的侵害，例如全食病害，这种病害可能导致毁灭性的作物损失。对于其中一个菌株，我们已经鉴定了负责这种抗真菌活性的分子和基因，并表明当我们向生长培养基中添加吲哚 3 乙酸（一种存在于小麦根分泌物中的植物激素）时，抗真菌活性会增加两倍。在本提案中，我们的目标是更详细地研究土壤中产生抗生素的链霉菌在小麦根部的定殖。我们将对从小麦植株中分离出的 10 株抑制琼脂平板上全食真菌的菌株进行基因组测序，鉴定这些菌株产生的抗真菌药物，并确定它们是否可以保护小麦植株免受全食病害的侵害。我们还将尝试发现小麦根部分泌物中的哪些分子可以喂养这些细菌并启动其次级代谢产物的产生。由于链霉菌形成的孢子可以干燥并长期保存，因此我们有兴趣开发含有这些孢子的小麦种子包衣，以便细菌生长到发芽小麦植物的根部并保护它们免受疾病侵害。我们还将测试 VII 型分泌系统在这些菌株根部定植中的作用，因为我们有初步证据表明该系统有助于它们在小麦根部定植方面胜过其他细菌。我们的最终目标是开发链霉菌作为种子包衣，以保护小麦植物免受真菌病害，并从小麦根部分泌物中发现分子，我们可以用它们来启动体外次级代谢产物的产生，因为我们知道它们编码的次级代谢产物中 90%不是在实验室条件下制造的。这可以帮助我们从这些细菌中发现新的有用的分子。

项目成果

Soil, senescence and exudate utilisation: characterisation of the Paragon var. spring bread wheat root microbiome

土壤、衰老和分泌物利用：Paragon 变种的特征。

• DOI: 10.1101/2021.02.09.430461
• 发表时间: 2021-02-09
• 期刊: Environmental Microbiome
• 影响因子: 7.9
• 作者: Sam Prudence;J. Newitt;Sarah F. Worsley;M. Macey;J. Murrell;L. Lehtovirta;M. Hutchings
• 通讯作者: M. Hutchings

ActinoBase: tools and protocols for researchers working on Streptomyces and other filamentous actinobacteria.

ActinoBase：为研究链霉菌和其他丝状放线菌的研究人员提供的工具和协议。

• DOI: http://dx.10.1099/mgen.0.000824
• 发表时间: 2022
• 期刊: Microbial genomics
• 影响因子: 3.9
• 作者: Feeney MA

Streptomyces Endophytes Promote Host Health and Enhance Growth across Plant Species.

链霉菌内生菌促进宿主健康并促进植物物种的生长。

• DOI: http://dx.10.1128/aem.01053-20
• 发表时间: 2020
• 期刊: Applied and environmental microbiology
• 影响因子: 4.4
• 作者: Worsley SF