Story originally published December 17, 2012.
While mistletoe is a happy symbol of this festive holiday season, few people likely know that the plant itself lives a life of underworld drama and espionage. Researchers associated with Thompson Rivers University have started to unravel some of the mysteries connected to North American dwarf mistletoe’s fascinating life story.
Dr. Cynthia Ross Friedman, a TRU biologist, has built her career around understanding how mistletoe lives off of trees in Canada’s pine forests to become a successful parasite.
Through recent work with an undergraduate student (Lyssa Martin) and TRU Alumna, Dr. Lori Phillips, Dr. Ross Friedman has now shown that mistletoe has become adapted to defend itself against other kinds of parasites that would steal its hard-won riches.
No Christmas Story here, the modus operandi of mistletoe is straight from a mobster novel. Mistletoe ‘hires’ protection—it harbours a fungus that lives among its cells. This ‘hired gun’ guards its boss against invasion from free-living moulds (and other fungi) that would rob it of the fruits of its labours.
In tests, they found that the good-guy “protective” fungus, one akin to our own gut flora, could actually halt the growth of nasty mould fungi that would otherwise attack the mistletoe. This has serious implications: knock out the good-guy fungus, and the bad one might take over, acting as a possible way to control mistletoe parasitism.
Although “good” fungi have been discovered in other plants, this is a first for dwarf mistletoe, and only the second time there has been any report of any fungus like this in any mistletoe.
Their findings are published in the December 2012 issue of The American Journal of Botany
Dr. Ross Friedman and her team’s findings could lead to further research identifying natural defences through which humans could protect themselves from fungal diseases.
Dr. Cynthia Ross Friedman,
TRU Professor Biological Sciences
What am I looking at?
The following is provided by Dr. Cynthia Ross Friedman…
“It is Arceuthobium americanum (Lodgepole Pine Dwarf Mistletoe or American Dwarf Mistletoe), and we have collected it from lodgepole pine (Pinus contorta var. contorta) near Stake Lake, Kamloops, BC.
Most dwarf mistletoes are ‘dioecious’, meaning they have separate male and female plants. The one being held is a female, and I would guess it was sampled mid-August (Editor’s note: Photo was taken Aug. 23, 2010. Impressive).
It is a particularly neat shot, as it shows three generations of female flowers: young unfertilized flowers (the smallest scale-like nubs), fruits that are in their first summer of development (look like bishop’s hats or “miters”), and fruits that are in their second summer of development (the larger, curved fruit).
Young female flowers develop in late August, overwinter, and will be fertilized the following spring to form immature fruit that then enter their first summer of development. These immature fruit will go into another overwintering period, and then complete development over the second summer. At the end of that second summer, the seed is explosively-discharged from the mature fruit to find a new host pine. New flowers appear every year, hence the presence of all three generations in August.
What is being held is the part that is visible and would be sticking out of the bark; the mistletoe itself also has a root-like system growing throughout the bark of the pine tree.”
UPDATE: Published research in February 2013 told of some interesting discoveries. This from the researcher, Dr. Cynthia (Cindy) Ross Friedman.
“We have seen molecular evidence—namely, the visible accumulation of a specific protein—indicating that the dwarf mistletoe might raise its temperate (i.e., “get a fever”) in order to explosively-discharge its seeds. We are currently working towards obtaining direct evidence of this purported temperature increase. So far, the data support our ideas.”
Here’s how to find the research…
Ross Friedman, C.M., Ross, B. N., and Martens, G.D. (2013). An antibody against a conserved C-terminal consensus motif from plant alternative oxidase (AOX) isoforms 1 and 2 labels plastids in the explosive dwarf mistletoe (Arceuthobium americanum, Santalaceae) fruit exocarp. Protoplasma. 250(1): 317-323. DOI: 10.1007/s00709-012-0414-6
Photos by TRU undergraduate students Ivan Hartling and Jeffrey Jackson.