plant biology
Controlling root growth could help crops, combat climate change
R
oot systems are central to plant
survival and productivity, determining the plant’s access to nutrients and water and, therefore, the
iStock.com/ThomasVogel
A highly conserved ethylene signalling pathway can be targeted to control the direction of root growth, in turn creating deeper root systems that hold on to carbon and remove carbon dioxide from the atmosphere, according to scientists.
Environmental factors — like average
The team observed that genes throughout
rainfall or abundance of certain nutrients — can
the ethylene signalling pathway were activated
influence the shape of a plant’s root system. The
in response to mebendazole, and, in turn, the
angle at which roots grow produces different
pathway was carrying out the resulting changes
results in overall root architecture, with
in root growth. Biochemical investigation of this
horizontal root angles creating a shallower root
plant’s ability to withstand nutrient depletion and
system and vertical root angles creating a deeper
extreme weather like drought. Now, a research
root system. But scientists did not previously
team led by the Salk Institute for Biological Studies
understand clearly how these root angles were
has determined how a well-known plant hormone
being determined on a molecular level.
is crucial in controlling the angle at which roots
Plant hormones like auxin and cytokinin
grow. Their study, published in the journal Cell
have been connected to the angle of root
Reports, is understood to be the first time the
growth in the past, but the mechanisms of that
hormone, called ethylene, has been shown to be
connection have remained poorly understood.
involved in regulating lateral root angles that shape
In searching for molecules and pathways that
root systems — making the findings a revelation
were involved in setting the angle of root
for plant scientists optimising root systems.
growth, the research team genetically screened
“Deep roots lead to more durable carbon
Arabidopsis thaliana — a small flowering weed
storage in the soil and can make plants more
in the mustard family — for root system changes
resistant to drought, so the ability to control how
in response to thousands of molecules.
deep roots grow is really exciting for scientists
“We noticed this molecule called mebendazole
looking to engineer better root systems,” said
was causing the roots to grow more horizontally,”
senior author Professor Wolfgang Busch, Executive
said first author Wenrong He, a former
Director of Salk’s Harnessing Plants Initiative.
postdoctoral researcher in Busch’s lab. “When
relationship revealed that mebendazole inhibits the activity of a protein kinase called CTR1. This enzyme negatively regulates ethylene signalling, in turn promoting a shallow root system. The researchers now plan to target the ethylene signalling pathway in their efforts to engineer plants and crops that can withstand the environmental stresses of climate change and drought, as well as remove carbon dioxide from the atmosphere and store it deep underground. The presence of ethylene in root system architecture also inspires new questions, including whether another molecule exists that makes root systems deeper, or if there are specific genes in the already well-catalogued ethylene signalling pathway that can be targeted most effectively to promote deeper roots. “Since ethylene signalling is a widely
“We’re especially excited that the pathway we
we looked for what target proteins or pathways
conserved process in land plants, targeting the
found is conserved across many types of plants,
mebendazole was interacting with to have this
ethylene pathway is a very promising technique
meaning our findings can be widely applied to
effect, we discovered it was ethylene signalling
for root system engineering,” Busch said.
optimise root architecture in all land plants,
— and ethylene playing such an essential role in
“Hopefully, now we’ll be able to use this tool
including food, feed and fuel crops.”
root system architecture was really intriguing.”
to make crop species more resilient.”
www.LabOnline.com.au | www.LifeScientist.com.au
LAB+LIFE SCIENTIST - Apr/May 2024 | 27