ARC Centre of Excellence in Synthetic Biology


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21, Nov 2021

Rewinding evolution to secure our future foods

A radical bid to reverse evolution could see crop plants become disease-resistant and more productive – and it all relies on a clever change of gene address.

In a Nature C0mmunications paper just released, lead author Dr Briardo Llorente and colleagues describe an approach to move genes for critical functions from the nucleus of plant cells to their chloroplasts – the site of photosynthesis whereby sunlight is converted into energy for growth.

Dr Llorente, from the ARC Centre of Excellence in Synthetic Biology at Macquarie University, says the proposed change of genome address is not expected to alter critical functions of the plant. But it could have a powerful two-fold effect – crop resistance to diseases and improved photosynthesis leading to increased crop yields.

“Achieving sustainable food security is one of the most significant challenges of our time,” says Dr Llorente. “This has to be accomplished in the face of global climate change causing increasingly severe environmental stresses and more frequent plant disease outbreaks affecting crop yields.”

By reverting an evolutionary process that shaped the chloroplast genome, it’s hoped that future plant foods can be more productive and sustainable.

The chloroplast evolved from a photosynthetic bacterium that assimilated with a host cell more than a billion years ago. Over time, the photosynthetic bacterium transferred many of its genes to the nuclear genome of the host cell.

A two-way communication system

This resulted in the chloroplast becoming reliant on the nucleus and the emergence of two-way communication systems.

This has a couple of implications that can limit crop yield.

Many plant pathogens cause disease by disrupting the communication system.

Chloroplasts meanwhile communicate their needs to the nucleus. But instead of a tailored response back to the individual chloroplasts, the nucleus takes a more democratic approach, balancing out calls to the cellular help desk and sending back a somewhat equalised response.

“Our approach, which we think could have quite a drastic impact, opens new ways to develop plants that are more resistant to pathogens and capable of improved photosynthesis,” Dr Llorente says.

A simple change of address but with agricultural potential.

The catch with modern-day agriculture

“At the moment, we are up against several problems with modern-day agriculture,” says Dr Llorente. One of them is that pathogens pose a constant threat to food security. Breeding crops with protective qualities is a time-consuming and expensive process.  Achieving long-lasting protection against pathogens is also challenging because pathogens often adapt rapidly to overcome resistance.

By relocating key genes to the chloroplast genome, the researchers think the pathogens’ infection strategies will become ineffective as their targets will be moved to a safer new address inside the chloroplast.

“And in conferring chloroplasts more autonomy, we could allow each chloroplast to adapt its photosynthetic processes according to its individual functional and physiological needs, something that could lead to overall improved plant photosynthesis,” Dr Llorente says.

“We need to design our future crops to have significant gains in yields while simultaneously reducing agriculture’s environmental impact in the general context of climate change,” Dr Llorente says.