Streptomyces endophytes promote the growth of Arabidopsis thaliana-猫眼课题宝

DOI：

10.1101/532309

发表时间：

2019-01

期刊：

bioRxiv

影响因子：

通讯作者：

中科院分区：

其他

文献类型：

作者：

Sarah F. Worsley;J. Newitt;Johannes Rassbach;S. Batey;Neil A. Holmes;J. Murrell;B. Wilkinson;M. Hu

链霉菌在土壤中普遍存在，并以产生包括抗菌剂在内的次生代谢物而闻名。它们越来越多地从植物根中分离出来，几项研究表明，它们被特异性地招募到模式植物拟南芥的根际和内层。在这里，我们测试了这样一个假设，即链霉菌对拟南芥的生长有有益的影响，并可能被用作植物益生菌。为了做到这一点，我们选择性地从表面清洗的海参根中分离出链霉菌，并为五个菌株生成了高质量的基因组序列，我们将它们命名为L2，M2，M3，N1和N2。L2、M2和M3的再侵染显著增加了植株的生物量，而N1和N2对植株的生长有负面影响，这可能是因为它们产生了可以与植物甾醇结合的多烯天然产物，从而抑制了植物的生长。氮气表现出广谱的抗菌活性，并产生类似于菲律宾磷脂的多烯，其中包括14-羟基异链蛋白，它抑制了小麦全蚀菌Gaeumannmyces graminis var。小黑麦。吲哚-3-乙酸(IAA)使氮素的抗真菌活性整体上提高了~2倍，表明氮素可能在根际竞争中起作用。此外，用氮气孢子包衣小麦种子可以保护小麦幼苗免受全蚀病的侵染。我们得出的结论是，至少有一些土壤中的链霉菌对拟南星具有促进生长的好处，而另一些可能被利用来保护作物免受疾病侵染。重要的是，我们必须减少对农用化学品的依赖，人们对使用细菌菌株促进植物生长和预防疾病的兴趣日益浓厚。我们的研究跟进了有关拟南芥专门招募链霉菌到其根部的报道。特别是，我们测试了这样的假设，即这些细菌可以为它们的A.thaliana宿主提供好处，并且从这些植物中分离的菌株可能被用作益生菌。我们从表面洗涤的海参根中分离出链霉菌菌株，并对5株系统发育不同的菌株进行了基因组测序。基因组挖掘和生物测定表明，所有5株菌株都具有促进植物生长的特性，包括产生IAA、铁载体和ACC脱氨酶活性。三个菌株在体外和在土壤中联合应用均能显着促进拟南芥的生长。另一种能产生有效的类似菲林的抗真菌代谢物，我们用它作为种衣剂来保护萌发的小麦种子免受真菌病原菌的侵染。小麦全食真菌(Tritici)我们的结论是，将链霉菌的最佳组合引入根部微生物群可以为植物提供显著的好处。

Streptomyces bacteria are ubiquitous in soils and are well-known for producing secondary metabolites, including antimicrobials. Increasingly, they are being isolated from plant roots and several studies have shown they are specifically recruited to the rhizosphere and the endosphere of the model plant Arabidopsis thaliana. Here we test the hypothesis that Streptomyces bacteria have a beneficial effect on A. thaliana growth and could potentially be used as plant probiotics. To do this, we selectively isolated streptomycetes from surface washed A. thaliana roots and generated high quality genome sequences for five strains which we named L2, M2, M3, N1 and N2. Re-infection of A. thaliana plants with L2, M2 and M3 significantly increased plant biomass individually and in combination whereas N1 and N2 had a negative effect on plant growth, likely due to their production of polyene natural products which can bind to phytosterols and reduce plant growth. N2 exhibits broad spectrum antimicrobial activity and makes filipin-like polyenes, including 14-hydroxyisochainin which inhibits the Take-all fungus, Gaeumannomyces graminis var. tritici. N2 antifungal activity as a whole was upregulated ~2-fold in response to indole-3-acetic acid (IAA) suggesting a possible role during competition in the rhizosphere. Furthermore, coating wheat seeds with N2 spores protected wheat seedlings against Take-all disease. We conclude that at least some soil dwelling streptomycetes confer growth promoting benefits on A. thaliana while others might be exploited to protect crops against disease. Importance It is vital that we reduce our reliance on agrochemicals and there is increasing interest in using bacterial strains to promote plant growth and protect against disease. Our study follows up reports that Arabidopsis thaliana specifically recruits Streptomyces bacteria to its roots. In particular, we test the hypothesis that these bacteria can offer benefits to their A. thaliana hosts and that strains isolated from these plants might be used as probiotics. We isolated Streptomyces strains from surface washed A. thaliana roots and genome sequenced five phylogenetically distinct strains. Genome mining and bioassays indicated that all five strains have plant growth promoting properties, including production of IAA, siderophores and ACC deaminase activity. Three strains significantly increased A. thaliana growth in vitro and when applied in combination in soil. Another produces potent filipin-like antifungal metabolites and we used it as a seed coating to protect germinating wheat seeds against the fungal pathogen Gaeumannomyces graminis var. tritici (wheat Take-all fungus). We conclude that introducing an optimal combination of Streptomyces strains into the root microbiome can provide significant benefits to plants.

Streptomyces endophytes promote the growth of Arabidopsis thaliana

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