Research teams at the Sainsbury Laboratory Cambridge University (SLCU) and
the University of Bordeaux have discovered Phloem Unloading Modulator (PLM),
a novel gene affecting nutrient trafficking by altering the channels
connecting neighboring plant cells also known as plasmodesmata. These
nanoscale membrane-lined channels link plant cells together and enable the
transfer of essential substances.

The study shows that Arabidopsis plants without the PLM gene released more
substances from the phloem (specialized tissue for long distance transport)
at the tips of their roots. With the help of a fluorescent protein as a
proxy for macromolecules, the scientists saw that the PLM gene had a
controlling effect on the amount of phloem unloading. To find out how the
PLM gene did this, they looked at different cell interfaces in the roots of
seedling plants.

According to lead author Dr. Dawei Yan from SLCU, they found mutating PLM
relieves a trafficking bottleneck that was previously reducing the outward
movement of nutrients from the vascular system to the rapidly growing
tissues in the roots. Further tests revealed that PLM is involved in the
biosynthesis of sphingolipids, a class of lipids associated with plant
development and response to the environment.

[www.slcu.cam.ac.uk]
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