Shimura Hanako, Masuta Chikara, Koda Yasunori
Laboratory of Horticultural Science, Research Faculty of Agriculture, Hokkaido University, Sapporo, Hokkaido, Japan.
Research Faculty of Agriculture, Hokkaido University, Sapporo, Hokkaido, Japan.
Methods Mol Biol. 2018;1746:161-172. doi: 10.1007/978-1-4939-7683-6_12.
In nature, mycorrhizal association with soilborne fungi is indispensable for orchid families. Fungal structures from compatible endo-mycorrhizal fungi in orchid cells are digested in cells to be supplied to orchids as nutrition. Because orchid seeds lack the reserves for germination, they keep receiving nutrition through mycorrhizal formation from seed germination until shoots develop (leaves) and become photoautotrophic. Seeds of all orchid species surely geminate with the help of their own fungal partners, and this specific partnership has been acquired for a long evolutional history between orchids and fungi.We have studied the interactions between orchids and mycorrhizal fungi and recently conducted transcriptome analyses (RNAseq) by a next-generation sequencing (NGS) approach. It is possible that orchid RNA isolated form naturally grown plants is contaminated with RNAs derived from mycorrhizal fungi in the orchid cells. To avoid such contamination, we here prepared aseptically germinated orchid plants (i.e., fungus-free plants) together with a pure-cultured fungal isolate and field-growing orchid samples. In the cDNA library prepared from orchid and fungal tissues, we found that partitivirus-like sequences were common in an orchid and its mycorrhizal fungus. These partitivirus-like sequences were closely related by a phylogenetic analysis, suggesting that transmission of an ancestor virus between the two organisms occurred through the specific relation of the orchid and its associated fungus.
在自然界中，与土传真菌形成菌根共生关系对兰科植物来说是必不可少的。兰花细胞中来自兼容内生菌根真菌的真菌结构在细胞内被消化，从而作为营养物质提供给兰花。由于兰花种子缺乏萌发所需的储备物质，它们从种子萌发开始，直到幼苗发育出（叶子）并成为光合自养植物，一直通过菌根形成来获取营养。所有兰花物种的种子都必定在其自身真菌伙伴的帮助下萌发，这种特定的共生关系是兰花和真菌在漫长的进化历史中形成的。我们研究了兰花与菌根真菌之间的相互作用，最近通过下一代测序（NGS）方法进行了转录组分析（RNAseq）。从自然生长的植物中分离出的兰花RNA可能会被兰花细胞中菌根真菌来源的RNA污染。为避免这种污染，我们在此制备了无菌萌发的兰花植株（即无菌植株）以及纯培养的真菌分离物和田间生长的兰花样本。在从兰花和真菌组织制备的cDNA文库中，我们发现类多分体病毒序列在一种兰花及其菌根真菌中很常见。通过系统发育分析发现这些类多分体病毒序列密切相关，这表明一种祖先病毒在这两种生物之间的传播是通过兰花及其相关真菌的特定关系发生的。
