Weed gave up sex long ago

Aug 07, 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: Dairy farms asked to consider breeding no-horn cows

Related Stories

Plant immunity comes at a price

Nov 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 ...

Integrated bioinformatics gateways portal and interface

Sep 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 ...

Evolution can cause a rapid reduction in genome size

Apr 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 ...

Is this the beginning of the end of plant breeding?

Jun 09, 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

Dairy farms asked to consider breeding no-horn cows

Mar 28, 2015

Food manufacturers and restaurants are taking the dairy industry by the horns on an animal welfare issue that's long bothered activists but is little known to consumers: the painful removal of budding horn ...

Italian olive tree disease stumps EU

Mar 27, 2015

EU member states are divided on how to stop the spread of a disease affecting olive trees in Italy that could result in around a million being cut down, officials said Friday.

China starts relocating endangered porpoises: Xinhua

Mar 27, 2015

Chinese authorities on Friday began relocating the country's rare finless porpoise population in a bid to revive a species threatened by pollution, overfishing and heavy traffic in their Yangtze River habitat, ...

A long-standing mystery in membrane traffic solved

Mar 27, 2015

In 2013, James E. Rothman, Randy W. Schekman, and Thomas C. Südhof won the Nobel Prize in Physiology or Medicine for their discoveries of molecular machineries for vesicle trafficking, a major transport ...

User comments : 0

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.