Genetics are thought to play a significant role in why some pinyon pines survive drought, and some don't. But a biologist at Northern Arizona University believes a newly discovered fungus is making the real difference between life and death.
Catherine Gehring studies pinyon pines that live in the dry, nutrient-poor cinders around Sunset Crater Volcano. For years she suspected a beneficial fungus was at work within the root system of the trees, but it wasn't until a banner crop of wild summer mushrooms popped up in 2013 that she was able to collect a sample. "Somebody actually brought it to me and said, 'Hey! I found this in the pinyon-juniper. Are you interested?' Gehring says. "I'd been hunting for it for years, so it was nice to actually see it and actually find that it matched with the DNA sequencing to the thing that we had been looking for for so many years."
Gehring says the fungus has tiny filaments that reach beyond the roots to find water and even break up rocks to release nitrogen and phosphorous for the tree. In turn, the fungus receives sugars that the pinyon pines produce through photosynthesis...kind of a buddy system of survival. Gehring says, "We can look across the landscape and find trees that survived drought, then those that did not. And we see that they have different communities of these microryzol, or beneficial fungi, and if we grow the plants without their beneficial fungi, we see that the drought-tolerant and intolerant basically behave the same. But, if we give them their unique community of fungi that they tend to recruit, we see a big difference in how well they survive and grow."
Climate change models have projected that pinyon pines could vanish from Arizona by 2090. But, Gehring's research suggests those with drought-resistant DNA, along with their microbe pals, could thrive despite warmer, drier conditions.