ABSTRACT

Corybas carsei is one of New Zealand’s most endangered orchids, with a single remaining population in the Whangamarino Wetland (North Island). Although orchid mycorrhizae have proved a critical aspect of orchid conservation globally, until now mycorrhizal fungi of C. carsei have not been identified or utilised for conservation. This study investigated fungal associates of C. carsei using three culture-based approaches: fungi grown directly from fragments of root tissue, from pelotons isolated from root-collars, and directly from macerated protocorm tissue. Fungi were cultured and identified as a diverse array of fungi through Sanger sequencing of the internal transcribed spacer region. This included the fungus Pleurotus purpureo-olivaceus (Basidiomycota; Agaricales), which belongs to a genus containing putative orchid mycorrhizal fungi, and the ericoid mycorrhizal fungus Oidiodendron eucalypti (Ascomycota; Leotiomycetes incertae sedis). No Rhizoctonia-like fungi, typical of orchid mycorrhizae, were found through any approach and fungi cultured in the present study likely represent endophytes, rather than mycorrhizal fungi. The potential of C. carsei having unculturable mycorrhizal associations, and the challenge this presents to conservation efforts, is discussed.

摘要

紫堇是新西兰最濒危的兰花之一，在旺阿马里诺湿地（北岛）仅存一株。尽管兰花菌根已被证明是全球兰花保护的一个重要方面，但迄今为止，卡氏兰花的菌根真菌尚未被鉴定或用于保护。本研究使用三种基于培养的方法研究了C. carsei的真菌伴生：直接从根组织碎片中生长的真菌、从根颈分离的大群中生长的真菌以及直接从浸软的原球茎组织中生长的真菌。培养真菌并通过内部转录间隔区的桑格测序鉴定为多种真菌。其中包括真菌Pleurotus purpureo-olivaceus（担子菌门；伞菌目），属于包含假定的兰花菌根真菌和杜鹃花菌根真菌（子囊菌门；Leotiomycetes incertae sedis）的属。通过任何方法都没有发现兰花菌根典型的丝核菌样真菌，并且本研究中培养的真菌可能代表内生菌，而不是菌根真菌。讨论了C. carsei具有不可培养的菌根群落的潜力，以及这给保护工作带来的挑战。