The giant mycoheterotrophic orchid Erythrorchis altissima is associated mainly with a divergent set of wood-decaying fungi
The giant mycoheterotrophic orchid Erythrorchis altissima is associated mainly with a divergent set of wood-decaying fungi
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DOI：
10.1111/mec.14524
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发表时间：
2018-03-01
影响因子：
4.9
通讯作者：
Yukawa, Tomohisa
中科院分区：
文献类型：
--
作者：
Ogura-Tsujita, Yuki;Gebauer, Gerhard;Yukawa, Tomohisa
攀缘兰花 Erythrorchis altissima 是世界上最大的真菌异养菌。尽管之前的体外研究表明，臭椿与木材腐烂真菌具有独特的共生关系，但人们对这种巨型兰花如何仅通过菌根真菌满足其碳和营养需求知之甚少。在这项研究中，使用 26 个个体的根样本对臭椿的菌根真菌进行了分子鉴定。此外，还对某一地点的五种臭椿中与五种真菌的体外共生萌发和稳定同位素组成进行了检查。总共从兰花根中鉴定出属于担子菌门九目的 37 个真菌操作分类单位 (OTU)。大多数真菌OTU是木材腐烂真菌，但地下根部有外生菌根红菇。从菌根根分离的两种真菌在体外诱导种子发芽和随后的幼苗发育。碳和氮稳定同位素丰度的测量表明，臭椿是一种完全的真菌异养生物，其碳主要来自木材腐烂真菌。所有结果都表明，E. altissima 与多种木材和土壤栖息真菌有关，其中大多数是木材腐烂类群。这种多面性的联系使臭椿能够进入木质残骸中的大量碳库，并且是如此大的霉菌异养生物进化的关键。
The climbing orchid Erythrorchis altissima is the largest mycoheterotroph in the world. Although previous in vitro work suggests that E. altissima has a unique symbiosis with wood-decaying fungi, little is known about how this giant orchid meets its carbon and nutrient demands exclusively via mycorrhizal fungi. In this study, the mycorrhizal fungi of E. altissima were molecularly identified using root samples from 26 individuals. Furthermore, in vitro symbiotic germination with five fungi and stable isotope compositions in five E. altissima at one site were examined. In total, 37 fungal operational taxonomic units (OTUs) belonging to nine orders in Basidiomycota were identified from the orchid roots. Most of the fungal OTUs were wood-decaying fungi, but underground roots had ectomycorrhizal Russula. Two fungal isolates from mycorrhizal roots induced seed germination and subsequent seedling development in vitro. Measurement of carbon and nitrogen stable isotope abundances revealed that E. altissima is a full mycoheterotroph whose carbon originates mainly from wood-decaying fungi. All of the results show that E. altissima is associated with a wide range of wood- and soil-inhabiting fungi, the majority of which are wood-decaying taxa. This generalist association enables E. altissima to access a large carbon pool in woody debris and has been key to the evolution of such a large mycoheterotroph.