Loblolly pine pollen is everywhere

Loblolly pine pollen is everywhere

The loblolly pine pollen coating your home, car and pets this week is the trees’ attempt to spread their genes far and wide. Really far and really wide. The yellow dust has been found to travel up to 1,800 miles from its source. Despite its exposure to moisture, cold and UV radiation from sunlight during its long travels, more than half of the pollen can still do its job making pine tree seeds, says forest biologist Claire Williams, who studies airborne pollen at the National Evolutionary Synthesis Center in Durham.  [What the work does not have, Williams emphasizes, is implications for people with pollen allergies. Fewer than 5 percent of people react to pollen from pines, and she is doing her best to stamp out what she calls urban myths about allergenic pine] [Weather.Com reports all pine species contribute to airborne pollen counts, but they are seldom a cause of acute allergic reaction.

Williams and her colleagues used a hand-held device called a spore sampler to capture and analyze pollen found miles out to sea off the Outer Banks of North Carolina during the spring from 2006 to 2009. Sampling by helicopter and by ferry, they found viable pine pollen as far as 2,000 feet in the air and 25 miles offshore.. More than 50 percent of loblolly pine pollen still germinates after drifting those distances, they discovered. “The odd thing is that pollen germination did not decline as distance increased,” she says. “You would expect germination to gradually drop off as pollen floats further away, but that’s not the case.”

This could be more than just an annoyance, Williams says. Loblolly pollen’s incredible staying power could have profound implications if and when the USDA approves genetically engineered trees. “Long-distance dispersal of transgenic pine pollen is a potential problem if that pollen is viable,” says Williams, who also works with the Forest History Society. Her research was funded by the USDA.

The loblolly pine, Pinus taeda, grows on nearly 60 million acres in the Southern U.S. and provides more than 15 percent of the world’s timber. “Roughly one billion loblolly pines are planted in the American South each year,” Williams says. “But right now none are genetically modified.” On the other hand, potency of far-flung pollen could be good news for forests facing climate change, Williams adds. “Under human-induced climate change we expect higher wind speeds and more frequent storms will move pollen and seeds even farther from the source,” she says. That means that genes needed to adapt to warmer temperatures will have a better chance of mixing with populations that don’t have them, she explained.

The findings were published online March 26 in the American Journal of Botany.

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