Weed gave up sex long ago

August 7, 2007

The ability of plants to self-pollinate – a big factor in the spread of weeds – is much older than previously thought in one widely studied species, leading biologists say. The findings show that at least in plant evolution, sex with others may be more trouble than it’s worth.

The mustard-like plant Arabidopsis thaliana lost interest in sex and started self-pollinating at least a million years ago, said plant geneticists led by Magnus Nordborg, associate professor of molecular and computational biology at the University of Southern California.

The results contradict a 2004 estimate from North Carolina State University that A. thaliana began self-pollinating in the last 400,000 years.

“We can rule out a very recent change to self-fertilization,” said Chris Toomajian, USC research associate in molecular and computational biology and co-author of two new papers on A. thaliana in Science Express and Nature Genetics.

Self-pollination, or selfing, confers a major advantage to weedy species. A selfing plant can invade new territory by itself and colonize it alone.

The potential downside -- a nasty case of inbreeding depression -- is averted by rare sexual breeding. According to an older study, 1 percent of all A. thaliana have received pollen from other plants of the species.

“A little sex goes a long way,” Nordborg said.

The researchers arrived at their findings by studying common combinations of genetic variants.

Certain variants at different points on the genome tend to go together, like blond hair and blue eyes in humans.

This phenomenon, called linkage disequilibrium, is important because it helps predict what an individual’s genome looks like based on information from selected locations.

In their Science Express study, published online July 26, the researchers used the genome-wide pattern of LD to estimate the time at which selfing evolved.

Since cross pollination mixes two plants’ genomes and disrupts some combinations of variants, a recent transition to selfing should have left a footprint in the LD pattern for A. thaliana.

Specifically, the researchers expected to find a relatively high level of LD, because after the transition to selfing the disruption of variant combinations would have slowed dramatically.

But the LD pattern instead suggested that selfing evolved “on the order of a million years ago or more,” and perhaps soon after the evolution of the species itself.

In their Nature Genetics study, published online August 5, the researchers used the LD pattern to design a method for mapping the associations between genetic variants and corresponding physical traits in A. thaliana.

“This is of broad interest, as Arabidopsis is likely to become an important model for identifying the genetic basis of evolutionary change,” Nordborg said.

Source: University of Southern California

Explore further: Plant immunity comes at a price

Related Stories

Plant immunity comes at a price

November 21, 2014

Plants are under permanent attack by a multitude of pathogens. To win the battle against fungi, bacteria, viruses and other pathogens, they have developed a complex and effective immune system. And just as in humans, this ...

Integrated bioinformatics gateways portal and interface

September 22, 2011

An easy-to-use bioinformatics interface has been developed by a research group led by Tetsuro Toyoda called the RIKEN Bioinformatics And Systems Engineering division (BASE), Yokohama. The web-service-based tool, called Semantic-JSON, ...

Evolution can cause a rapid reduction in genome size

April 21, 2011

(PhysOrg.com) -- It would appear reasonable to assume that two closely related plant species would have similar genetic blueprints. However, scientists from the Max Planck Institute for Developmental Biology in Tübingen, ...

Is this the beginning of the end of plant breeding?

June 9, 2009

No human is a clone of their parents but the same cannot be said for other living things. While your DNA is a combination of half your mother and half your father, other species do things differently. The advantage of clonal ...

Recommended for you

Researchers design first artificial ribosome

July 29, 2015

Researchers at the University of Illinois at Chicago and Northwestern University have engineered a tethered ribosome that works nearly as well as the authentic cellular component, or organelle, that produces all the proteins ...

Meet the high-performance single-molecule diode

July 29, 2015

A team of researchers from Berkeley Lab and Columbia University has passed a major milestone in molecular electronics with the creation of the world's highest-performance single-molecule diode. Working at Berkeley Lab's Molecular ...

Researchers build bacteria's photosynthetic engine

July 29, 2015

Nearly all life on Earth depends on photosynthesis, the conversion of light energy into chemical energy. Oxygen-producing plants and cyanobacteria perfected this process 2.7 billion years ago. But the first photosynthetic ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.