The human body is awash in microbes. They live a top our skin, within our guts, between our teeth, below our fingernails. Unnerving as it may seem, many play a key role in maintaining human health by producing vitamins, helping digestion, and edging out nasty pathogens.
It should come as no surprise, then, that plants too have communities of bacteria and fungi that help them thrive. To uncover these microscopic plant partners, Emily Wilson, a graduate student at UC Merced, is studying the bacteria associated with lodgepole and limber pines in Yosemite National Park. Many of these organisms aid their host tree by accelerating growth, providing protection from insect pests, and offering resistance to drought.
To conduct her study, Wilson backpacks her way across the park, stopping at meadows many miles apart to snip samples of tree needles and buds.
Once back at campus, Wilson uses these tissue samples to grow colonies of symbiotic tree microbes. She then scans each colony with the laser beam of a device called BARDOT. BARDOT can analyze the three-dimensional growth patterns unique to each microbe species, and learn over time to identify new colonies with scans stored in its memory. BARDOT was originally developed to help food scientists identify bacteria contaminating food. Wilson was the first to use the device in environmental research.
Trees could come by their helper microbes in one of two ways, Wilson says. "Bacteria could be packaged within seeds found within the pine cone by the parent tree. Or the tree could pick up endophytes from its environment, through the roots or needles or openings in the bark."
By sampling adult trees and saplings, Wilson says, "I can see whether the parents and the little seedlings have the same bacteria. Comparing trees in different meadows gives me an idea of whether there is variation due to location."
Wilson's findings will not only expand our understanding of conifer biology, but also improve agricultural practices. "If we could engineer or apply endophytes to plants, we could have more successful and sustainable crops for bioenergy and food," Wilson says.