Moss Sperm Surviving Desiccation

When I think about moss reproduction, I usually think about the fact that mosses have flagellated sperm that require water to swim to the female archegonium that holds the egg. Researchers at Portland State University have been thinking about sperm survival when desiccated. I think that this is a really interesting question. Imagine that it rains and a moss sperm begins its journey swimming toward and egg. What happens if mid-travel the water dries up and the sperm is stranded? Can the sperm cell survive and resume its journey when it is wet again? 

In this study, the effects of desiccation on sperm cells were examined in three moss species.

Shortlidge, E. E., Rosenstiel, T. N. and Eppley, S. M. 2012. Tolerance to environmental desiccation in moss sperm. New Phytologist 194: 741–750.

They found that a fraction of the sperm were able to survive desiccation (e.g., Ceratodon purpureus, on average 17% survived) and the desiccation tolerance did not vary significantly among species. These results indicate the possibility of a sperm bank existing on the landscape. I have heard about a seed bank and a spore bank, but had not thought about a sperm bank before. I think that this is a pretty cool idea and as the authors mention has significant implications for understanding moss mating systems. That is just one finding from this paper. There is a lot more about desiccation tolerance, the effect of sucrose on sperm survival, and sperm variation. I highly recommend checking out this paper if you are interested in learning more. I think that it is good science and a well-written research article. Kudos to the authors.