Mysterious moss

Published 3:09 pm Wednesday, June 24, 2020

JOHNSON CITY—How are mosses and humans alike and how can moss, plants often trampled underfoot, help humans survive and thrive? Dr. Aruna Kilaru of the East Tennessee State University Department of Biological Sciences can tell you, although some of the terms might require an encyclopedia.

 Kilaru, who has five students in her group, leads two research projects at ETSU, one of which has been studying bryophyte mosses that she says date back about 500 million years and are highly resilient to environmental stressors. A doctoral student of Kilaru’s, Imdadul Haq, led the research, and his findings titled “An endocannabinoid catabolic enzyme FAAH and its paralogs in an early land plant reveal evolutionary and functional relationship with eukaryotic orthologs” were published earlier this year in the “Scientific Reports” journal from the publishers of “Nature.”

 This study of Physcomitrella patens reveals that moss plants produce a lipid, anandamide, and its enzyme Fatty Acid Amide Hydrolase, or FAAH, both of which are also present in humans.

 This lipid is expected to make the moss better able to withstand changes in temperature and hydration, just as in humans, where anandamide and FAAH can have an effect on the brain when released “on demand,” to enable recovery from challenging situations, including pain, Kilaru says.

 “I must say, that with this publication and other work he has done, Imdadul has made some enormous contributions to the field,” says Kilaru, who has been in the field of plant lipid biochemistry for 15 years and studying mosses for at least a decade. “In terms of the research itself, we are perhaps the only lab in the world that is working on this particular lipid anandamide and its functions in mosses.”

 Haq’s five years of research under Kilaru’s tutelage was supported by ETSU Research Development Committee grants and a National Science Foundation award of more than $679,000 to study the functional implications of mammalian lipids in mosses. Haq also successfully defended his dissertation and was accepted to the University of Pennsylvania for post-doctoral work.

 Anandamide is a compound that binds to cannabinoid receptors in the human brain leading to neural stimulation. These are the same receptors that psychoactive compounds in marijuana interact with to give a “blissful feeling” when used.

 “Until recently, the effects of marijuana and anandamide were thought to be limited to mammals,” says Kilaru, who joined ETSU’s faculty in 2011. “So basically, the compound that is released in our brain to mitigate pain is also present in mosses.”

 While enabling people to feel “high” is not a goal of Kilaru and her research team, relieving pain or stress could be if they find that the inhibitors of FAAH in mosses are more effective than the current ones used in humans. “Some level of medicinal therapeutic value definitely could evolve based on understanding the structure and specificity of FAAH from various organisms, including mosses,” the associate professor of biology says.

 Additionally, there’s a lot to learn from these particularly hardy mosses—which long ago survived the adaptation from a watery environment to land— that can benefit agriculture and food supplies.

 “We know from other studies that the climate conditions and the land composition were very harsh 500 million years ago, and for these plants to survive and be successful all these years, they must have had some magical qualities,” Kilaru says with a smile. “Having this anandamide is probably one of those properties that is unique to those plants and enabled their transition.”

 Mosses can survive being 90% dehydrated, she says, and with a sprinkle of water, come back to life. “So if we can understand the process by which they survive, we can manipulate the crop lines to have similar ability to tolerate drought, and that would be a huge contribution to the global food demand, to have agronomic crops that are drought tolerant.

 “In fact, mosses can also tolerate freezing cold, as well as high temperatures,” she continued. “So if there is one system that is capable of doing all this, and you could put that system into crop plants so that they can tolerate a temperature drop or an increase beyond optimum, that would be a huge savior, especially in our current global climate conditions where everything is being quite erratic.”

 While Kilaru’s labs have broken new ground in moss research, those strides are just the first steps toward actually making these medicinal and agricultural possibilities come to fruition.

 “We don’t know how anandamide is made in mosses,” she says. “So far we have identified only FAAH in its biochemical pathway. We don’t know if it is only FAAH that breaks it down. There could be other FAAH or other enzymes that are capable of breaking it down.

 “Our immediate goal is to understand the metabolic pathway of anandamide, which means: How is it made? How is it broken down? A second aspect of that is: How does it work? Then, of course, we want to answer: What is its role in plants? What kind of functions is it taking part in?”

 Because of COVID-19, Kilaru’s labs are paused, but “the work is going on,” she says. Moss plants that make more FAAH, less FAAH or no FAAH— mutants generated by her team— await reopening of the labs and analysis.

 The mosses have waited millions of years. They surely can wait a few weeks more.

 For more information, see the article on Haq and Kilaru written by Hannah Warren in the fall 2019 “Illuminated” Magazine, published by the ETSU School of Graduate Studies, at https://www.etsu.edu/gradschool/documents/illuminated/illuminated_fall_2019.pdf.