This is a secondary blog, inspired by Bengoldacre.posterous.com, where Ben Goldacre "witters on and on and on about things that are too long to post on twitter and not clever enough to post on [his] main blog at www.badscience.net". TALKING PLANTS TOO is a scrapbook of ideas for TALKING PLANTS proper and for other stuff … including direct reproduction of posts I just can't bear to not find again (with URL up front, hopefully sufficient attribution given the low readership of this blog...)
Farting plants have a built-in stink bomb that deters
“OH MY goodness! It smells like someone has broken wind.” So
Musah of the University at Albany in New York, who has discovered a
previously unknown defence mechanism in plants: roots that actively release a
nasty smell when they sense the touch of a potential threat.
Many plants are famed for their putrid smells, and it has
been known for decades that unpleasant sulphurous odours are released when soil
is disturbed around the roots of some plants – including members of the Mimosa genus.
Until now, it has been assumed that these odours are released passively as a
result of tissue damage, like when a bay leaf is crushed or onions are cut with
But Musah has found that the roots of some species actively
release their foul smell. Her team made this discovery while growing seedlings
of Mimosa pudica, known for its sensitive leaves that fold up when
touched. They found that this plant’s roots are also touch-sensitive,
releasing the odour when accosted (Plant Physiology, DOI: 10.1104/pp.15.01705).
The smell – a cocktail of sulphur compounds – seems to be
released from tiny hair-like sacs less than half a millimetre long and dotted
along the roots of the plants, which collapse after the odours are released.
Even a seedling just a few centimetres high can fill a room
with a disgusting smell, says Musah. Seedlings grown in sterile conditions
still produce the sulphuric scent, indicating that it is a product of the roots
themselves rather than coming from associated bacteria.
“Even a seedling just a few centimetres high can fill a
room with a disgusting smell”
Perhaps more astonishing is that the roots seem to
distinguish between different kinds of touch.
“The odour response is
selective,” Musah says. A single touch with a finger is always enough to
trigger the stench, her team found, but the roots never respond to a glass or
metal object. Nor do they usually react to a single touch from soil, while
dragging the roots across soil does trigger the smell.
Just how the plant senses these distinctions is unknown.
This selectiveness presumably helps the plants differentiate between the touch
of predators and harmless objects.
But the smell might not be aimed at predators, suggests
Anthony Trewavas of the University of Edinburgh, UK. Instead, it may act to
fend off roots from other plants that encroach upon its territory. “The fact
that they are smelly to us is irrelevant.”
The phenomenon is not limited to one species. Musah has
found that at least six other Mimosa species produce the smell
and now plans to study plants in the closely related Acacia genus.
The phenomenon could turn out to be widespread, says Baluska.
(Image: Nigel Cattlin/Alamy Stock Photo)
This article appeared in print under the headline
“Farting plants kick up a stink if irked”