The lack of gravity in space doesn't seem to affect certain aspects of root growth in the botanical equivalent of lab rats, a new study suggests. In 2010, researchers sent petri dishes loaded with seeds of two particular strains of Arabidopsis to the International Space Station, where astronauts tended growth experiments on the plants—the first to monitor root development in great detail, the scientists say. Specifically, the researchers measured how roots "waved" (how the root tip wandered through a small circle over the course of a 24-hour period) and "skewed" (began growing at an angle when it touched a surface) every 6 hours during their first 15 days of growth. Previous studies, all of them earthbound, have suggested that these traits are genetically determined but that gravity also plays a major role in waving and skewing, but the new findings reveal otherwise, the researchers report online today in BMC Plant Biology. In general, the seedlings grown in orbit were smaller but exhibited the same degree of waving seen in those strains grown on Earth. However, the root tips of space-grown plants (top) showed a tendency to skew a bit more than their earthbound counterparts (bottom) when they encountered an object, mostly due to their larger number of cells (edges of cells denoted by blue tick marks), the researchers say.
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