Bryophyte-microbe interactions on the remote oceanic island of St. Helena

苔藓植物（苔藓、地钱和金鱼藻）是许多陆地生态系统功能和生物多样性的主要贡献者。与其相关的微生物群落（微生物组）一起，细菌在营养循环中起着关键作用;然而，这些群落的许多方面都知之甚少或完全被忽视。Brabente微生物组的组成被认为在物种之间变化，但也受到栖息地的影响，并且可能在干扰梯度之间变化。苔藓植物微生物组可以包括广泛的生物体，包括固氮蓝藻、甲烷营养菌和真菌，其关联发生在地下和地上，并且范围从紧密的内共生体到更松散的附生关联。植物和微生物之间的相互作用可以对宿主表型产生显著影响，介导诸如病原体抗性、胁迫耐受性、营养获取、生长和繁殖等过程。到目前为止，大多数关于植物-微生物相互作用的研究几乎完全集中在“高等”维管植物上，而对微生物群以及微生物群如何受到其相关微生物群落的影响以及反之亦然知之甚少。圣赫勒拿岛是一个小的（121.7平方公里）和孤立的火山岛在南大西洋与温和的热带气候缓和的海洋是英国海外领土的一部分圣赫勒拿，Ascension和特里斯坦-库尼亚。它有独特的植物群和动物群，具有极高的地方性。然而，生物多样性受到诸如生境破坏和入侵物种等人为压力的严重威胁。苔藓、地钱和金鱼藻是植物群的重要组成部分，它们的大部分多样性都在圣赫勒拿本土和高度威胁的山峰国家公园云雾林的残余碎片中发现。博士项目的目的是首次研究圣赫勒拿岛的微生物群落组成，测试微生物和真菌之间的相互作用，并确定微生物组和相互作用如何在物种、宿主基因型、栖息地类型和沿着干扰梯度上变化。该项目将采取综合方法，将圣赫勒拿岛的广泛实地工作与基于实验室的方法结合起来，包括最先进的测序和成像技术以及体外研究。博士生将使用DNA测序，生物信息学，统计学和微生物群落结构分析技术来分析微生物组（细菌和真菌）。植物-微生物的相互作用将使用基于实验室的体内培养实验和扫描电子显微镜和光学显微镜进行研究和记录。博士生将与自然历史博物馆和帝国学院伦敦的多学科团队合作，并直接与圣赫勒拿政府合作，该项目的CASE合作伙伴。

Bryophytes (mosses, liverworts and hornworts) are major contributors to the functioning and biodiversity of many terrestrial ecosystems. Together with their associated microbial communities (microbiomes), bryophytes play key roles in nutrient cycling; however, many aspects of these communities are poorly understood or completely ignored. The composition of bryophyte microbiomes is thought to vary across species but is also influenced by habitat and may vary across disturbance gradients. Bryophyte microbiomes may comprise a wide range of organisms including nitrogen-fixing cyanobacteria, methanotrophic bacteria and fungi, with associations occurring both below and above ground and ranging from intimate endosymbioses through to more loose epiphytic associations. Interactions between plants and microbes can have a significant effect on the host phenotype, mediating processes such as pathogen resistance, stress tolerance, nutrient acquisition, growth and reproduction. To date, most research on plant-microbe interactions has focused almost exclusively on 'higher' vascular plants and comparatively little is known about the microbiomes of bryophytes and how bryophytes are influenced by their associated microbial communities and vice versa. St Helena is a tiny (121.7 km2) and isolated volcanic island in the South Atlantic Ocean with a mild tropical climate tempered by the ocean that is part of the UK Overseas Territory of St. Helena, Ascension and Tristan da Cunha. It has a unique flora and fauna with an exceptionally high level of endemism. However, biodiversity is severely threatened by anthropogenic pressures such as habitat destruction and invasive species. Mosses, liverworts and hornworts are an important component of the flora, with most of their diversity found in the remnant fragments of St. Helena native and highly threatened cloud forest in the Peaks National Park.The aims of the PhD project are to characterise for the first time the microbiome community composition of bryophytes on St. Helena, test for interactions between microbes and fungi, and determine how microbiomes and interactions vary across species, host genotype, habitat type and along disturbance gradients. This project will take an integrative approach, combining extensive field work on St. Helena with laboratory-based methodologies including state-of-the-art sequencing and imaging techniques and in vitro studies. The PhD student will characterise the microbiomes (bacteria and fungi) using DNA sequencing, bioinformatics, statistical and microbial community structure analysis techniques. The plant-microbe interactions will be studied and documented using in vivo laboratory-based cultivation experiments and scanning electron and light microscopy. The PhD student will collaborate with a multi-disciplinary team at the Natural History Museum and Imperial Collage London as well as work directly with the St. Helena's Government, CASE partner on the project.