Scientists unlock secrets of hybrid species

23:14, Mar 10 2014

A universal law that explains how hybrid species such as the broccoflower survive and thrive has been discovered by Massey University scientists.

It is a discovery that, among other things, could help inform the natural breeding of different types of hybrid brassicas.

Computational biologist professor Murray Cox and molecular biologist Austen Ganley led the research that analysed what happens when a new species is formed.

Their findings were published last week in the Public Library of Science online journal, Genetics.

Prof Cox said hybrids were surprisingly common and could be seen in the cotton used to make bed-sheets, the wheat in bread, and in New Zealand alpine plants.

"When two very different species suddenly merge together, a new species is created instantaneously that contains two different sets of machinery, or RNA (ribonucleic acid) as it's known," Prof Cox said.


"Some parts of this machinery won't work together, so we asked the question, how does this hybrid survive?"

His team used advanced computational biology methods to sequence and analyse hundreds of millions of RNA copies of a fungus found in grass.

"This particular fungus [epichloe endophyte] is one of the good guys," he said. "The plant gives the fungus a place to live, and the fungus produces chemicals that kill insects that try to eat the grass. This hidden relationship is a key reason for the success of New Zealand's multibillion-dollar dairy industry."

Prof Cox was amazed to find that the RNA levels in the grass fungus were almost identical to the patterns found in cotton - the only other hybrid species that has undergone similar analysis.

"These species are radically different, for starters, one is a plant, the other is a fungus," he said.

"Therefore, we realised we had identified universal rules that dictate how gene expression has to behave . . . regardless of what exact species those hybrids are."

The hybrid's genes mimic one parent or the other.

"The RNA levels showed one copy effectively gets turned off. It's not simply an average of what its parents have.

This pattern occurs in both fungi and plants - in other words, there are universal rules that control gene expression levels in hybrids across the tree of life."

Prof Cox said what was not yet fully understood was what was causing the rules. If discovered it could be used to inform areas of agriculture.

Manawatu Standard