Why The Tobacco Plant Gave Up Its Immune System

A mutation in the Rdr1 gene has left Nicotiana benthamiana plants with a weakened immune system but also helped to ensure their survival in harsh climates.

AsianScientist (Nov. 4, 2015) – Researchers from the Queensland University of Technology (QUT) have found that the ancient Australian native tobacco plant Nicotiana benthamiana traded its immune system for an early growth spurt that allowed it to survive dry environments. Their results have been published in Nature Plants.

Known as Pitjuri to indigenous Aboriginal tribes, N. benthamiana seeds were first sent by an Australian scientist to an American scientist in 1939 and have been passed from lab to lab all over the world.

“This plant is the ‘laboratory rat’ of the molecular plant world,” said study corresponding author Peter Waterhouse, a professor at QUT.

“We know, through a molecular clock and fossil records, that this particular plant has survived in its current form in the wild for around 750,000 years.”

Lead researcher Dr. Julia Bally said determining the exact species had led researchers on a quest to find out how the plant managed to survive in the wild for such a long period of time.

“We have discovered that it is the plant equivalent of the nude mouse used in medical research,” Bally said.

“The plant has lost its ‘immune system’ and has done that to focus its energies on being able to germinate and grow quickly, rapidly flower, and set seed even with a small amount of rainfall.”

By comparing DNA sequences of different Pitjuri plants, the researchers found a mutation in the Rdr1 gene, which allowed the plant to survive the harsh weather conditions of central Australia.

“The plant has worked out how to fight drought—its number one predator—in order to survive through generations,” commented Bally.

Waterhouse added that scientists could use this discovery to investigate other niche or sterile growing environments where plants were protected from disease—and space was an intriguing option.

“So the recent film The Martian, which involved an astronaut stranded on Mars growing potatoes while living in an artificial habitat, had a bit more science fact than fiction than people might think,” Waterhouse said.

He said the team’s findings also have implications for future genetic research back here on Earth.

“Scientists can now know how to turn other species into ‘nude mice’ for research purposes. So just as nude mice can be really good models for cancer research, ‘nude’ versions of crop plants could also speed up agricultural research,” he said.

The fact that the N. benthamiana variety from central Australia had doubled its seed size also opened the door for investigations into how N. benthamiana could be used commercially as a biofactory, as seeds were an excellent place in which to make antibodies for pharmaceutical use, Waterhouse added.

Researchers around the world can access Professor Waterhouse’s open source website, to study the genomes of seven family members: http://www.benthgenome.qut.edu.au/

The article can be found at: Bally et al. (2015) The Extremophile Nicotiana bethamiana Has Traded Viral Defence for Early Vigour.


Source: Queensland University of Technology.
Disclaimer: This article does not necessarily reflect the views of AsianScientist or its staff.

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