you ever wondered why stems grow upwards and roots downwards? Why
plants always seem to turn towards the light and climbing plants run up
the trellis rather than down?
The answer is simple: auxin. But
maybe not that simple, since plant hormones—and auxin is a plant
hormone—are regulated by complex combinations of various processes. Elke
Barbez, Jürgen Kleine-Vehn and Jirí Friml, connected to VIB and UGent
recently identified an important new link in the transport of auxin
through the plant, resulting in auxin being stored at specific sites.
The results were published by the journal Nature.
Auxin surrenders its secrets
was already interested in auxin in the 19th century. Only in recent
years, however, has the hormone started to relinquish its secrets,
thanks to intensive molecular research. Auxin is produced in the young,
growing parts of plants and then transported throughout the plant – to a
low-lying stem for example. The stem needs to straighten out as soon as
possible to be able to absorb the sun’s rays efficiently; therefore
more auxin will be delivered to the underside of the stem than to the
topside, resulting in the underside growing faster and the stem
straightening out. For the same reason, plants in front of windows will
always turn to the light. This dynamic regulation of auxin transport
allows plants to take optimal advantage of local and changing
A new means of transport for auxin?
transport of auxin through the plant plays a vital role. And, from all
appearances, it is not a simple matter. The VIB researchers identified
an important new link and means of transport for auxin: PILS proteins.
PILS proteins are vital for auxin-dependent plant growth and regulate
the intracellular storage of the hormone. It is exactly this
compartmentalizing of auxin that seems functionally important for the
various developmental processes.
Growing crops more efficiently: the right amount of auxin in the right place
auxin levels at the right moment and in the right place result in
better growth and greater yields. Better regulation of auxin levels
would make plants grow more efficiently. The researchers hope to
contribute to the development of more efficient growing processes by
continuing to unravel auxin transport processes.