Nav: Home

Lab-made hormone may reveal secret lives of plants

January 22, 2018

A lab-designed hormone may unlock mysteries harbored by plants.

By developing a synthetic version of the plant hormone auxin and an engineered receptor to recognize it, Howard Hughes Medical Institute (HHMI) Investigator Keiko Torii and colleagues are poised to uncover plants' inner workings.

The new work, described January 22, 2018, in the journal Nature Chemical Biology, is "a transformative tool to understand plant growth and development," says Torii, a plant biologist at the University of Washington. That understanding may have big agricultural implications, raising the possibility, for instance, of a new way to ripen strawberries and tomatoes.

To plants, the hormone auxin is king. Among many other jobs, auxin helps sunflowers track sunlight, roots grow downward, and fruits ripen. This wide range of jobs, as well as the fact that every cell in a plant can both produce and detect auxin, makes it tricky to tease apart the hormone's various roles. "It's been a huge mystery as to how such a simple molecule can do so many different things," Torii says.

She and her colleagues set out to create a new way to study plants' responses to auxin by designing a lab-made version of the hormone that can be precisely controlled. Working with synthetic chemists in Japan, the researchers added a little bump to auxin's structure -- hydrocarbon rings that auxin doesn't normally contain. The researchers then tweaked plants' auxin receptor, a protein that sits on the outside of plant cells and detects auxin. This time, the researchers removed a bulky amino acid from the receptor, creating a perfect-sized hole that cradles the lab-made auxin. That simple switch, called a "bump and hole" strategy, "is really elegant, actually," Torii says.

Next, the researchers tested whether this matched set -- the synthetic auxin and the synthetic receptor -- could do the same jobs as the cells' natural auxin/receptor pair. The intricately designed system worked beautifully, experiments on roots showed.

Normally, roots exposed to auxin stop growing down, and instead grow sideways by activating stem cells that break out of the main root. Torii compares the process, called lateral root development, to aliens bursting through stomachs. After detecting synthetic auxin, Arabidopsis plants genetically engineered to produce the synthetic auxin receptor behaved just like normal - growing the same sideways baubles of root branches.

What's more, roots that didn't have the synthetic auxin receptor were essentially "blind" to synthetic auxin, proof that the artificial hormone is detected by only the artificial receptor. Torii and her colleagues call this switch to synthetic auxin "chemical hijacking" -- a well-controlled takeover that will now allow researchers to tease apart the tangled web of auxin's jobs in plants.

With their system up and running, the researchers tested a long-standing question in plant biology. Scientists knew that germinating seedlings use auxin to grow quickly. But the identity of the exact receptor that allows this process to happen wasn't settled.

The scientific community had a suspect in mind. Torii's team produced a plant that lacked an auxin receptor called TIR1, and instead possessed a synthetic version. When exposed to artificial auxin, these seedlings began to grow rapidly, behaving exactly as if they had the normal receptor. The results suggest that seed elongation does indeed happen through the TIR1 receptor.

Other fundamental scientific questions can be addressed with this system, Torii says, such as auxin's role in corn ripening and in opening the stomata, the structures that let plants breathe.

One day, synthetic auxin might even find a place in agriculture. Auxin is currently sprayed on fruits to hasten ripening. But in high concentrations, the hormone can act as a plant-killing herbicide. Fruits engineered to carry the synthetic receptor could be ripened with the synthetic auxin hormone, Torii says, eliminating the need to spray auxin indiscriminately. But, she cautions, much more testing needs to be done before a synthetic hormone system can be used for growing food.
-end-
Naoyuki Uchida et al. "Chemical hijacking of auxin signaling with an engineered auxin-TIR1 pair." Nature Chemical Biology. Published online January 22, 2018. doi: 10.1038/nchembio.2555.

Howard Hughes Medical Institute

Related Plants Articles:

Transgenic plants against malaria
Scientists have discovered a gene that allows to double the production of artemisinin in the Artemisia annua plant.
How plants can tell friend from foe
The plant's immune system can recognize whether a piece of RNA is an invader or not based on whether the RNA has a threaded bead-like structure at the end, say University of Tokyo researchers.
Plants at the pump
Regular, unleaded or algae? That's a choice drivers could make at the pump one day.
How do people choose what plants to use?
There are about 400,000 species of plants in the world.
Defend or grow? These plants do both
From natural ecosystems to farmers' fields, plants face a dilemma of energy use: outgrow and outcompete their neighbors for light, or defend themselves against insects and disease.
How do plants protect themselves against sunburn?
To protect themselves against UV-B, which are highly harmful, plants have developed cellular tools to detect them and build biochemical defenses.
Pea plants demonstrate ability to 'gamble' -- a first in plants
An international team of scientists from Oxford University, UK, and Tel-Hai College, Israel, has shown that pea plants can demonstrate sensitivity to risk -- namely, that they can make adaptive choices that take into account environmental variance, an ability previously unknown outside the animal kingdom.
A 'Fitbit' for plants?
Knowing what physical traits a plant has is called phenotyping.
How plants conquered the land
Research at the University of Leeds has identified a key gene that assisted the transition of plants from water to the land around 500 million years ago.
Plants are 'biting' back
Calcium phosphate is a widespread biomineral in the animal kingdom: Bones and teeth largely consist of this very tough mineral substance.

Related Plants Reading:

Plant: Exploring the Botanical World
by Phaidon Editors (Author)

The Plant Paradox: The Hidden Dangers in "Healthy" Foods That Cause Disease and Weight Gain
by Dr. Steven R Gundry M.D. (Author)

The Plant Paradox Cookbook: 100 Delicious Recipes to Help You Lose Weight, Heal Your Gut, and Live Lectin-Free
by Dr. Steven R Gundry M.D. (Author)

Urban Jungle: Living and Styling with Plants
by Igor Josifovic (Author), Judith de Graaff (Author)

The Secret Life of Plants: a Fascinating Account of the Physical, Emotional, and Spiritual Relations Between Plants and Man
by Peter Tompkins (Author), Christopher Bird (Author)

From Seed to Plant
by Gail Gibbons (Author)

Peterson Field Guide to Medicinal Plants and Herbs of Eastern and Central North America, Third Edition (Peterson Field Guides)
by Steven Foster (Author), James A. Duke (Author)

Plant-Based Nutrition, 2E (Idiot's Guides)
by Julieanna Hever M.S. R.D. (Author), Raymond J. Cronise (Author), Penn Jillette (Foreword)

Your Brain on Plants: Improve the Way You Think and Feel with Safe―and Proven―Medicinal Plants and Herbs
by Nicolette Perry (Author), Elaine Perry (Author)

Raven Biology of Plants
by Ray F. Evert (Author), Susan E. Eichhorn (Author)

Best Science Podcasts 2018

We have hand picked the best science podcasts for 2018. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

The Right To Speak
Should all speech, even the most offensive, be allowed on college campuses? And is hearing from those we deeply disagree with ... worth it? This hour, TED speakers explore the debate over free speech. Guests include recent college graduate Zachary Wood, political scientist Jeffrey Howard, novelist Elif Shafak, and journalist and author James Kirchick.
Now Playing: Science for the People

#486 Volcanoes
This week we're talking volcanoes. Because there are few things that fascinate us more than the amazing, unstoppable power of an erupting volcano. First, Jessica Johnson takes us through the latest activity from the Kilauea volcano in Hawaii to help us understand what's happening with this headline-grabbing volcano. And Janine Krippner joins us to highlight some of the lesser-known volcanoes that can be found in the USA, the different kinds of eruptions we might one day see at them, and how damaging they have the potential to be. Related links: Kilauea status report at USGS A beginner's guide to Hawaii's otherworldly...