Interaction between an isolate of dark-septate fungi and its host plant Saussurea involucrata.

A dark-septate endophytic (DSE) fungus EF-M was isolated from the roots of an alpine plant Saussurea involucrata Kar. et Kir. ex Maxim. The fungus was identified by sequencing the PCR-amplified rDNA 5.8S gene and ITS regions. The sequence was compared with similar sequences in the GenBank, and results showed that EF-M was congeneric to Leptodontidium. Resynthesis study was conducted to clarify the relationship between the root endophyte EF-M and the host plant S. involucrata using the material grown in sterile culture bottle. In roots recovered 6 weeks after inoculation, epidermal cells were colonized by intercellular and intracellular hyphae and "microsclerotia" formed within individual cells in the epidermis layers. However, hyphae did not invade the cortex and the stele. There were no profound effects of endophyte EF-M on plant root development, but significant differences were detected in plant height and shoot dry weight between the treatments. The present study is the first report hitherto on DSE fungi in S. involucrata.