Mitochondrial genes move to the nucleus -- but it's not for the sex

Mar 22, 2007

Why mitochondrial genes ditch their cushy haploid environs to take up residence in a large and chaotic nucleus has long stumped evolutionary biologists, but Indiana University Bloomington scientists report in this week's Science that they've uncovered an important clue in flowering plants.

"Plants that reproduce clonally or are capable of self-pollinating have transferred more genes from the mitochondrion to the nucleus," said graduate student Yaniv Brandvain, lead author of the paper.

That discovery, Brandvain explained, is unexpected. The most obvious benefit of being part of the nuclear genome is recombination, after all, but little recombination takes place in self-pollinating species. So what, exactly, might be luring mitochondrial genes to the nucleus?

"We're not quite sure why yet, but we've hypothesized that successful mitochondrial genes are pairing up with related nuclear genes," Brandvain said. "When you have two successful genes that depend on each other, it's best for them not to be in an environment in which they will recombine. It would be like breaking up a good musical duo."

Mitochondrial and nuclear genomes replicate separately, and a new and beneficial mutation in the mitochondrion could be separated from partner genes in the nucleus -- in the production of eggs or pollen, via meiosis. But the mating system determines whether or not this separation is permanent. With self-pollination, the components separated by meiosis are brought back together. In contrast, the components are further separated if they mix and match haphazardly during out-crossing.

Brandvain said the finding contradicts the expectation that mitochondrial genes migrate to the nucleus because of the evolutionary benefits conferred by sexual recombination. "The benefits of sex could have driven the transfer," he said. "There are powerful arguments out there for that. But that's just not what we saw."

Brandvain, fellow graduate student Michael Barker, and their advisor, IUB evolutionary biologist Michael J. Wade, examined papers that identified the sexual properties of plants that show evidence of mitochondrial-nuclear transfer. In all, the scientists collected data from plant species representing 170 genera.

Funding for this research was provided by the National Science Foundation.

Citation: "Gene Co-Inheritance and Gene Transfer," Science, vol. 315, iss. 5819

Source: Indiana University

Explore further: Thousands worldwide march against Monsanto and GM crops

Related Stories

The vital question: Why is life the way it is?

Apr 01, 2015

The Vital Question: Why is life the way it is? is a new book by Nick Lane that is due out on April 23rd. His question is not one for a static answer but rather one for a series of ever sharper explanations—explanations that a ...

STAT3 protein found to play a key role in cancer

Jun 25, 2009

A protein called STAT3 has been found to play a fundamental role in converting normal cells to cancerous cells, according to a new study led by David E. Levy, Ph.D., professor of pathology and microbiology at NYU Langone ...

Toward mitochondrial plant cell factories

Jan 15, 2015

In work published in Scientific Reports, a group of researchers led by Jo-Ann Chuah and Keiji Numata of the RIKEN Center for Sustainable Resource Science have devised a new strategy for selectively delive ...

DNA sheds light on why largest lemurs disappeared

Dec 16, 2014

Ancient DNA extracted from the bones and teeth of giant lemurs that lived thousands of years ago in Madagascar may help explain why the giant lemurs went extinct. It also explains what factors make some surviving ...

Recommended for you

Birds 'weigh' peanuts and choose heavier ones

May 23, 2015

Many animals feed on seeds, acorns or nuts. The common feature of these are that they have shells and there is no direct way to know what's inside. How do the animals know how much and what quality of food ...

Q&A: Why are antibiotics used in livestock?

May 22, 2015

Wal-Mart, the world's biggest retailer, is the latest company to ask its suppliers to curb the use of antibiotics in farm animals. Here's a rundown of what's driving the decision: ...

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.