Fungal endophytes utilize the seeds of their hosts to colonize new areas

Background/Question/Methods

In the study of microbial ecology, some researchers appear unable to let go of the “everything is everywhere” paradigm. This viewpoint requires dispersal limitation of microbes to be negligible. One assumption of this viewpoint is that microbes are primarily passively dispersed by wind or water. This assumption is premature, as very few microbial ecologists have examined dispersal. To address this issue, I cultured fungal endophytes from plant and seed tissue of fourteen different species of plants from Mount St. Helens, Washington. Mount St. Helens is a primary successional habitat, in which dispersal limitation has been demonstrated for several larger forms of life. Host species include both class 1 and class 2 fungal endophyte hosts. Tissues were surface sterilized and cultured on potato dextrose agar. Fungal monocultures were developed and identified using DNA extraction and PCR as well as microscopically.

Results/Conclusions

Fungal endophytes were present in the surface-sterilized seeds of every plant tested, and several species showed vertical transmission of endophytes. These results suggest that microbes may disperse into new areas by co-opting the dispersal vectors of their hosts, rather than passively. They also suggest that vertical transmission of class 2 fungal endophytes may be more prevalent that previously believed.