Monday, April 5, 2010

Long Range Tree Sperm

My car is yellow. I don't own a yellow car.

As of this weekend the pollen is out in force. Published online in the American Journal of Botany is a new study about the long distance dispersal and germination abilities of pine pollen.

The loblolly pine (Pinus taeda) is a commercially important forest species that grows over 60 million acres of the the southern United States. It is a rapidly growing tree that reaches a height of approximately 35 meters and has needles in bundles of three that measure 12-22 centimeters long. The male cones start shedding their pollen between February and April, the peak being reached in late March and early April.

The author of the article, Claire Williams, traveled between the North Carolina barrier islands and the mainland between 2006-2009. Her objective? Collect loblolly pine pollen that had been blown far offshore to see if it could still germinate. Williams and her colleagues used hand-held spore samplers, and they sampled from helicopters and ferries.

A majority of the pollen shed by the pine trees lands locally, but some catches the wind and can go surprising distances, up to 1800 miles. During that travel the pollen is exposed to the elements - extreme temperature, UV radiation, and moisture. The sampling found pollen 2000 feet up into the air and as far as 25 miles offshore. Of that pollen, 50% was still viable, distance was not a factor.

Viable long-distance pollen dispersal is a useful adaptive tool but can cause problems for agencies (like the USDA) that approve the use of transgenic trees. At present, transgenic trees are not planted but because of the commercially profitable nature of these trees it is a possibility they may be in the future. Studies like this show that tree DNA can become more widely spread than previously thought, potentially spreading transgenic traits such as drought tolerance and disease and pest resistance. A problem that increases with the age of the tree - a long lived species that produces more pollen the older it gets. The good news is that this long-distance pollen could potentially reach areas affected by climate change, increasing the gene pools and possibly the adaptability of some populations.

Here's the paper:
and a write-up:

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