Nav: Home

Scientists trace plant hormone pathway back 450 million years

October 24, 2016

WEST LAFAYETTE, Ind. - Purdue scientists got a glimpse into more than 450 million years of evolution by tracing the function of a hormone pathway that has been passed along and co-opted by new species since the first plants came onto land.

Flowering plants today, known as angiosperms, use the phytohormone abscisic acid (ABA) to keep seeds dormant until ready for germination and to open and close stomates, tiny openings on leaves used to control gas exchange.

"This hormone is important for drought tolerance," said Jody Banks, Purdue professor of botany and plant pathology. "When plants are water-stressed, ABA levels shoot up and close the stomates so the plants won't wilt as quickly."

It was unclear, however, what kind of role ABA played in ferns and other lycophytes, which Banks studies. Like many of her peers, Banks assumed that ABA would also play a role in stomate function.

But when she developed a line of mutant ferns that could not process ABA, she found that there was no difference between her mutants and wild type ferns that were water-stressed.

Banks shelved the research for nearly two decades before teaming with scientists at Australia's University of Tasmania and Germany's University of Würzburg. Together, they determined that ABA plays a key role in determining the sex of ferns, using a mechanism that was co-opted by flowering plants to tolerate desiccation.

Matching the genes of Arabidopsis, a model flowering plant, and the fern Ceratopteris richardii, scientists at the University of Tasmania found the homologous fern gene responsible for ABA signaling. Scientists at the University of Würzburg then found that the proteins produced when the ABA signaling pathway is turned on do not interact with proteins that would open and close stomates. They realized that regulating stomate closing by ABA was novel to angiosperms, which evolved from ferns about 150 million years ago.

ABA, they found, promotes femaleness in ferns. When a wild type plant is exposed to ABA, the plant becomes female. When ABA pathways are disrupted, as with the mutants Banks studied, the plants become male, even in the presence of ABA. They also discovered that ABA is linked to spore dormancy in ferns, just as ABA is linked to seed dormancy in angiosperms.

"Promoting a dormant state was likely the original function of ABA as plants came up out of the water onto the land," Banks said. "You wouldn't need that dormancy if you were living in water. But on land, you need to have dormancy to survive desiccation." Banks and her colleagues will continue studying other ABA pathways in lycophytes and ferns, as well as hormones that control of sex of plants.
-end-


Purdue University

Related Evolution Articles:

An evolution in the understanding of evolution
In an open-source research paper, a UVA Engineering professor and her former Ph.D. student share a new, more accurate method for modeling evolutionary change.
Chemical evolution -- One-pot wonder
Before life, there was RNA: Scientists at Ludwig-Maximilians-Universitaet (LMU) in Munich show how the four different letters of this genetic alphabet could be created from simple precursor molecules on early Earth -- under the same environmental conditions.
Catching evolution in the act
Researchers have produced some of the first evidence that shows that artificial selection and natural selection act on the same genes, a hypothesis predicted by Charles Darwin in 1859.
Guppies teach us why evolution happens
New study on guppies shows that animals evolve in response the the environment they create in the absence of predators, rather than in response to the risk of being eaten.
Undercover evolution
Our individuality is encrypted in our DNA, but it is deeper than expected.
Evolution designed by parasites
In 'Invisible Designers: Brain Evolution Through the Lens of Parasite Manipulation,' published in the September 2019 issue of The Quarterly Review of Biology, Marco Del Giudice explores an overlooked aspect of the relationship between parasites and their hosts by systematically discussing the ways in which parasitic behavior manipulation may encourage the evolution of mechanisms in the host's nervous and endocrine systems.
Tracing the evolution of vision
The function of the visual photopigment rhodopsin and its action in the retina to facilitate vision is well understood.
Directed evolution comes to plants
Accelerating plant evolution with CRISPR paves the way for breeders to engineer new crop varieties.
Pain free, thanks to evolution
African mole-rats are insensitive to many different kinds of pain.
Evolution in the gut
Evolution and dietary habits interact and determine the composition of bacteria in the digestive tract.
More Evolution News and Evolution Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Rethinking Anger
Anger is universal and complex: it can be quiet, festering, justified, vengeful, and destructive. This hour, TED speakers explore the many sides of anger, why we need it, and who's allowed to feel it. Guests include psychologists Ryan Martin and Russell Kolts, writer Soraya Chemaly, former talk radio host Lisa Fritsch, and business professor Dan Moshavi.
Now Playing: Science for the People

#538 Nobels and Astrophysics
This week we start with this year's physics Nobel Prize awarded to Jim Peebles, Michel Mayor, and Didier Queloz and finish with a discussion of the Nobel Prizes as a way to award and highlight important science. Are they still relevant? When science breakthroughs are built on the backs of hundreds -- and sometimes thousands -- of people's hard work, how do you pick just three to highlight? Join host Rachelle Saunders and astrophysicist, author, and science communicator Ethan Siegel for their chat about astrophysics and Nobel Prizes.