2017 ASHS Annual Conference

Cypripedium Linn., a most important genus in Orchidaceae, is becoming endangered due to excessive deforestation and poor reproductive capability. Mycorrhizal fungi play a crucial role in the growth and development of Cypripedium plants. The interactions between mycorrhizal fungi and Cypripedium plants indigenous to Changbai mountain in northeastern China are still unclear. The root anatomy of C. calceolus, C. guttatum, C. macranthum, C. macranthum f. white, C. shanxiense, and C. ventricosum was compared, and dynamic changes in the mycorrhizal development of Cypripedium roots were characterized. Cypripedium plants were collected from wild populations in Changbai mountain and transplanted to a field at Jilin Agricultural University on May 2010. Root tips were collected on 15 May, 15 June, and 15 July, 2012, and fixed in FAA solution. Thin sections were made with paraffin protocol and observed using compound microscope. The results showed that six varieties had similar root anatomical characteristics. The outer cortex cells of all species were rectangle except C. guttatum that was semi-round. The xylem and phloem of C. guttatum were in a ring arrangement, whereas those of the remaining Cypripedium varieties were in a radial pattern. The fungal hyphae penetrated individual cells of the cortex of all Cypripedium varieties and were surrounded by plasma membrane to form structures known as arbuscular. The hyphae development of arbuscular mycorrhizal fungi in Cypripedium root was growth-stage dependent. Fewer and smaller hyphae were observed in vegetative stage than in reproductive stage of Cypripedium plant. Fungal hyphae invasion and development repeated over the course of growing season. When Cypripedium plants were in blooming in June, a great number of newly developed hyphae were observed in cortex cells. Transplanting Cypripedium plants from wild population at this stage may fail due to the disturbance of active hyphae development and should be avoided for off-site conservation.