BACKGROUND AND AIMS In orchid conservation, quantifying the specificity of mycorrhizal associations, and establishing which orchid species use the same fungal taxa, is important for sourcing suitable fungi for symbiotic propagation and selecting sites for conservation translocation. For Caladenia subgenus Calonema (Orchidaceae), which contains 58 threatened species, we ask: (1) How many taxa of Serendipita mycorrhizal fungi do threatened species of Caladenia associate with? (2) Do threatened Caladenia share orchid mycorrhizal fungi with common Caladenia? (3) How geographically widespread are mycorrhizal fungi associated with Caladenia? METHODS Fungi were isolated from 127 Caladenia species followed by DNA sequencing of the ITS sequence locus. We used a 4.1- 6 % sequence divergence cut-off range to delimit Serendipita Operational Taxonomic Units (OTUs). We conducted trials testing the ability of fungal isolates to support germination and plant growth. A total of 597 Serendipita isolates from Caladenia, collected from across the Australian continent, were used to estimate the geographic range of OTUs. RESULTS Across the genus, Caladenia associated with 10 OTUs of Serendipita (Serendipitaceae) mycorrhizal fungi. Specificity was high, with 19 of the 23 threatened Caladenia species sampled in detail associating solely with OTU A, which supported plants from germination to adulthood. The majority of populations of Caladenia associated with one OTU per site. Fungal sharing was extensive, with 62 of the 79 Caladenia sampled in subgenus Calonema associating with OTU A. Most Serendipita OTUs were geographically widespread. CONCLUSIONS Mycorrhizal fungi can be isolated from related common species to propagate threatened Caladenia. Because of high specificity of most Caladenia species, only small numbers of OTUs typically need to be considered for conservation translocation. When selecting translocation sites, the geographic range of the fungi is not a limiting factor, and using related Caladenia species to infer the presence of suitable fungal OTUs may be feasible.

中文翻译：

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涉及常见和受威胁卡拉德尼亚（兰科）相同真菌类群的特定菌根关联：对保护的影响


背景和目的在兰花保护中，量化菌根关联的特异性，并确定哪些兰花物种使用相同的真菌类群，对于寻找适合共生繁殖的真菌和选择保护易位的地点非常重要。对于包含58种受威胁物种的Calonema亚属Calonema（兰科），我们问：（1）Caladenia的受威胁物种与多少种Serendipita菌根真菌相关？ （2）受威胁的卡拉德尼亚与普通卡拉德尼亚共享兰花菌根真菌吗？ (3) 与 Caladenia 相关的菌根真菌在地理上分布有多广？方法 从 127 个 Caladenia 物种中分离真菌，然后对 ITS 序列位点进行 DNA 测序。我们使用 4.1-6% 的序列分歧截止范围来界定 Serendipita 操作分类单位 (OTU)。我们进行了试验，测试真菌分离株支持发芽和植物生长的能力。从整个澳大利亚大陆收集到的来自 Caladenia 的总共 597 个 Serendipita 分离株被用来估计 OTU 的地理范围。结果 在整个属中，Caladenia 与 Serendipita（Serendipitaceae）菌根真菌的 10 个 OTU 相关。特异性很高，详细采样的 23 种受威胁 Caladenia 物种中，有 19 种仅与 OTU A 相关，OTU A 支持植物从发芽到成年。 Caladenia 的大多数种群每个地点都有一个 OTU。真菌共享广泛，在 Calonema 亚属中采样的 79 个 Caladenia 中，有 62 个与 OTU A 相关。大多数 Serendipita OTU 地理分布广泛。结论 可以从相关的常见物种中分离出菌根真菌来繁殖受威胁的卡拉德尼亚。 由于大多数 Caladenia 物种的高度特异性，通常只需要考虑少量 OTU 进行保护易位。在选择易位位点时，真菌的地理范围不是限制因素，使用相关的 Caladenia 物种来推断合适真菌 OTU 的存在可能是可行的。