Nav: Home

Recognizing others but not yourself: New insights into the evolution of plant mating

July 11, 2018

Self-fertilization is a problem, as it leads to inbreeding. Recognition systems that prevent self-fertilization have evolved to ensure that a plant mates only with a genetically different plant and not with itself. The recognition systems underlying self-incompatibility are found all around us in nature, and can be found in at least 100 plant families and 40% of species. Until now, however, researchers have not known how the astonishing diversity in these systems evolves. A team of researchers at the Institute of Science and Technology Austria (IST Austria) has made steps towards deciphering how new mating types evolve in non-self recognition self-incompatibility systems, leading to the incredible genetic diversity seen in nature. The results are published in this month's edition of Genetics.

In plants such as snapdragons and Petunia, when the pollen lands on the stigma, it germinates and starts growing. The stigma, however, contains a toxin (an SRNase) that stops pollen growth. Pollen in turn has a team of genes (F-box genes) that produce antidotes to all toxins except for the toxin produced by the "self" stigma. Therefore, pollen can fertlize when it lands on stigma that does not belong to the same plant, but not when it lands on the plant's own stigma. It may seem like a harsh system, but plants can use this toxin-antidote system to ensure that they only mate with a genetically different plant. This is important as self-fertilization leads to inbreeding, which is detrimental for the offspring.

In non-self recognition systems, the male (pollen) and female (stigma) genes work together as a team to determine recognition, so that a particular variation of the male- and female-genes forms a mating type. Non-self recognition systems are found all around us in nature and have an astonishing diversity of mating types, so the big question in their evolution is: how do you evolve a new mating type when doing so requires a mutation in both sides? For example, when there is a change in the female side (stigma), it produces a new toxin for which no other pollen has an antidote - so mating can't occur. Does this means that there needs to be a change in the male side (pollen) first, so that the antidote appears and then waits for a corresponding change in the stigma (female side)? But how does this co-evolution work when evolution is a random process? Is there a particular order of mutations that is more likely to create a new mating type?

To decipher how such complex non-self recognition systems evolved, Melinda Pickup, a postdoc in the group of Nick Barton at IST Austria and experimental plant biologist, worked together with theoreticians (and previous postdocs in the Barton group) Katarina Bodova, now Assistant Professor at Comenius University in Bratislava, Tadeas Priklopil, now postdoc at the University of Lausanne, as well as David Field, now Assistant Professor at the University of Vienna. This project is an example of a situation where tackling a biological question requires the skills of scientists from very different research fields, in this case the fields of evolutionary genetics, game theory and applied mathematics. "This project shows how collaboration between scientists with very different backgrounds can combine biological insight with mathematical analysis, to shed some light on a fascinating evolutionary puzzle," explains Nick Barton.

Through theoretical analysis and simulation, the researchers investigated how new mating types can evolve in a non-self recognition system. They found that there are different pathways by which new types can evolve. In some cases this happens through an intermediate stage of being able to self-fertilize; but in other cases it happens by staying self-incompatible. They also found that new mating types only evolved when the cost of self-fertilization (through inbreeding) was high. Being incomplete - i.e., having missing F-box genes that produce antidotes to female toxins - was found to be important for the evolution of new mating types: complete mating types (with a full set of F-Box genes) stayed around for the longest time, as they have the highest number of mating partners. New mating types evolved more readily when there was less mating types in the population. Also, the demographics in a population affect the evolution of non-self recognition systems: population size and mutation rates all influence how this system evolves.

So although it seems like having a full team of F-box pollen genes (and therefore antidotes) is the best way for new mating types to evolve, this system is complex and can change via a number of different pathways. Interestingly, while the researchers found that new mating types could evolve, the diversity of genes in their theoretical simulations were fewer compared to what is seen in nature. For Melinda Pickup, this observation is intriguing: "We have provided some understanding of the system, but there are still many more questions and the mystery of the high diversity in nature still exists."
-end-
IST Austria

The Institute of Science and Technology (IST Austria) is a PhD-granting research institution located in Klosterneuburg, 18 km from the center of Vienna, Austria. Inaugurated in 2009, the Institute is dedicated to basic research in the natural and mathematical sciences. IST Austria employs professors on a tenure-track system, postdoctoral fellows, and doctoral students. While dedicated to the principle of curiosity-driven research, the Institute owns the rights to all scientific discoveries and is committed to promote their use. The first president of IST Austria is Thomas A. Henzinger, a leading computer scientist and former professor at the University of California in Berkeley, USA, and the EPFL in Lausanne, Switzerland. The graduate school of IST Austria offers fully-funded PhD positions to highly qualified candidates with a bachelor's or master's degree in biology, neuroscience, mathematics, computer science, physics, and related areas. http://www.ist.ac.at

Institute of Science and Technology Austria

Related Evolution Articles:

Prebiotic evolution: Hairpins help each other out
The evolution of cells and organisms is thought to have been preceded by a phase in which informational molecules like DNA could be replicated selectively.
How to be a winner in the game of evolution
A new study by University of Arizona biologists helps explain why different groups of animals differ dramatically in their number of species, and how this is related to differences in their body forms and ways of life.
The galloping evolution in seahorses
A genome project, comprising six evolutionary biologists from Professor Axel Meyer's research team from Konstanz and researchers from China and Singapore, sequenced and analyzed the genome of the tiger tail seahorse.
Fast evolution affects everyone, everywhere
Rapid evolution of other species happens all around us all the time -- and many of the most extreme examples are associated with human influences.
Landscape evolution and hazards
Landscapes are formed by a combination of uplift and erosion.
New insight into enzyme evolution
How enzymes -- the biological proteins that act as catalysts and help complex reactions occur -- are 'tuned' to work at a particular temperature is described in new research from groups in New Zealand and the UK, including the University of Bristol.
The evolution of Dark-fly
On Nov. 11, 1954, Syuiti Mori turned out the lights on a small group of fruit flies.
A look into the evolution of the eye
A team of researchers, among them a zoologist from the University of Cologne, has succeeded in reconstructing a 160 million year old compound eye of a fossil crustacean found in southeastern France visible.
Is evolution more intelligent than we thought?
Evolution may be more intelligent than we thought, according to a University of Southampton professor.
The evolution of antievolution policies
Organized opposition to the teaching of evolution in public schoolsin the United States began in the 1920s, leading to the famous Scopes Monkey trial.

Related Evolution Reading:

Why Evolution Is True
by Jerry A. Coyne (Author)

Evolution
by Douglas J. Futuyma (Author), Mark Kirkpatrick (Author)

Evolution: A Visual Record
by Robert Clark (Author)

Evolution: The Human Story, 2nd Edition
by Dr. Alice Roberts (Author)

Evolution (Second Edition)
by Carl T. Bergstrom (Author), Lee Alan Dugatkin (Author)

Evolution: Making Sense of Life
by Carl Zimmer (Author), Douglas J. Emlen (Author)

Evolution: The Cutting-Edge Guide to Breaking Down Mental Walls and Building the Body You've Always Wanted
by Joe Manganiello (Author)

Evolutions: Fifteen Myths That Explain Our World
by Oren Harman (Author)

Improbable Destinies: Fate, Chance, and the Future of Evolution
by Jonathan B. Losos (Author)

Evolution: The Human Story
by DK Publishing (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

Dying Well
Is there a way to talk about death candidly, without fear ... and even with humor? How can we best prepare for it with those we love? This hour, TED speakers explore the beauty of life ... and death. Guests include lawyer Jason Rosenthal, humorist Emily Levine, banker and travel blogger Michelle Knox, mortician Caitlin Doughty, and entrepreneur Lux Narayan.
Now Playing: Science for the People

#491 Frankenstein LIVES
Two hundred years ago, Mary Shelley gave us a legendary monster, shaping science fiction for good. Thanks to her, the name of Frankenstein is now famous world-wide. But who was the real monster here? The creation? Or the scientist that put him together? Tune in to a live show from Dragon Con 2018 in Atlanta, as we breakdown the science of Frankenstein, complete with grave robbing and rivers of maggots. Featuring Tina Saey, Lucas Hernandez, Travor Valle, and Nancy Miorelli. Moderated by our own Bethany Brookshire. Related links: Scientists successfully transplant lab-grown lungs into pigs, by Maria Temming on Science...