Trail of 13 million year old gene transfer uncovered

Scientists from Agriculture Victoria have made a world-first scientific discovery that could have various applications in pasture and crop agriculture and positive implications for Australia’s multi-billion dollar livestock industries.

The breakthrough event is the first documented example of a gene being ‘horizontally’ transferred from a fungal endophyte to a flowering plant.

Fungal endophytes are organisms that live between living plant cells and can help plants to develop better resistance to pests and environmental stresses.

This work looked at the interaction between a particular fungal endophyte and perennial ryegrass – a flowering plant which is the low-cost home-grown feed stock that drives Australia’s clean and green $13.7 billion dairy industry and is a major contributor to the industry’s competitive advantage.

Agriculture Victoria’s Research Leader of Molecular Genetics, Professor John Forster, who is a co-author of the paper describing the work, explained that the discovery points to an “evolutionary puzzle,” which has now been decoded through the hard work and genetic sleuthing of a team of scientists at AgriBio, the Centre for AgriBioscience in Melbourne.

“Horizontal gene transfer is not in itself uncommon – for example, between bacterial and land plants – but this is the first ever documented event of horizontal gene transfer from a fungus to a flowering plant,” he said.

“The scientific significance is in the rarity of the event, since flowering plants have been interacting with fungi for millions of years.”

It was important to establish that this was a true occurrence of horizontal gene transfer.

Using genetic mapping techniques, the team determined that the complete gene of the endophyte was present in the perennial ryegrass plant’s genome. Its presence, therefore, could not be explained by contamination of the sample.

The team also examined the genomes of groups of grasses that are closely related to perennial ryegrass to see which of them contained the gene. Using this approach, they were able to show that the gene appears to have been horizontally transferred into a single common ancestor between nine and 13 million years ago.

“This is a narrow window in evolutionary terms, and really quite recent,” Prof. Forster said.

Further work will be undertaken to establish if this is a positive adaptation by certain grass species that has been retained over many generations.

The knowledge will be used to breed better forage grasses to strengthen Australian agriculture.

Source: Agriculture Victoria

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