Researchers Found That We Can Utilize Virus and E. coli for Plants

It’s not just humans and animals that can get some shots after this. Agricultural industry might soon use “plant vaccines” to improve crop health and enhance crop yield.

Researchers begin with rapeseed plants. They’ve discovered that a fungal virus called mycovirus can convert deadly fungal pathogens into beneficial fungus. It boosts those plants’ immune system, making them healthier and more resistant to diseases.

Rapeseed fields are pretty to look at, one can say they’re instagrammable, in fact. Aside of being nice-looking, they’re important ingredients for canola oil, which many people use for cooking. And not just that, they’re also a crucial crop for animal feed and biodiesel worldwide.

Unfortunately, rapeseed farms experience significant losses from the fungal pathogen called Sclerotinia sclerotiorum. It causes lesions and stem rot in the plants and it kills them within a few days after infection.

Senior author Daohong Jiang said, “The virus we identified can convert the fungus from a deadly pathogen in different plants to an endophytic fungus like a gentle sheep and protect these plants.”

Now, endophytic organisms can live within a plant without causing diseases and maintain a symbiotic relationship. “The research is important because we know plants have endophytic fungus, but where did it come from? The fungal virus might have played a role in the evolution of these fungi and that’s something we can look into in the future,” said Jiang.

When a rapeseed fungus got infected by the mycovirus, it loses the malevolence. Not killing the plant, the virus-infected fungus instead lives peacefully within it and even giving some benefits as well.

Jiang and his colleagues infected the rapeseeds by inoculating seeds with virus-infected fungus fragments and observed a boost in the plants’ immune system. They saw an 18% increase in weight and more root growth. With mycovirus, these plants can grow bigger, stronger, and resistant of other diseases.

“The fungal virus might be a good thing for the fungus because the fungus now recognizes the plant as ‘home’ instead of killing it. The virus turned a foe to a friend,” said Jiang.

sclerotinia sclerotiorum by Rasbak Wikimedia Commons

Efficient plant vaccines

In the fields, fungus-infected plants also suppressed stem rot, stimulated plant growth, and improved seed yield by 6.9% to 14.9%. This way, tackling crop diseases can be done by “vaccinating” the plants.

And not just that, researchers found that the fungal virus can be transmitted to other fungal pathogens quickly and efficiently throughout the field. Therefore, farmers won’t need to introduce the mycovirus one by one.

“If you treat the seed with virus-infected fungus, the fungus will grow with the plant throughout its life. Just like how we vaccinated our kids when they were born, the protection is life-long,” Jiang said.

The senior author noted that fungal pathogens are a topic that scientists haven’t been able to control in agricultural settings. To date, there are no plants with fungal-pathogen-resistance for these pathogens who attack a wide variety of plants.

Fungi cause more than 80% of crop disease and destroy one-third of all food crops annually, causing not just economic loss but also global poverty exacerbation.

“This fungal disease is also prevalent in the United States. Besides rapeseeds, the fungus also attacks sunflowers, beans and other crops. Our prevention method and research idea may benefit many others who are engaged in similar work and benefit agricultural production. It has a lot of potentials,” said Jiang.

Improving photosynthesis using E. coli

Us humans will try to stay the as far as we can from E. coli, but apparently plants can thrive with it. When Cornell University scientists introduced these bacteria to a key plant enzyme, they found out that it may speed up photosynthesis and eventually improve crop yields.

In the paper, published in the journal Nature Plants, the method is described, “Small subunits can determine enzyme kinetics of tobacco Rubisco expressed in Escherichia coli.”

Scientists know that crop yields would increase if they could accelerate the photosynthesis process. To refresh our memories, this process is where plants convert carbon dioxide (CO2), water and light into oxygen and eventually into sucrose, a sugar used for energy and for building new plant tissue.

Rubisco, as mentioned above, is a slow enzyme that pulls carbon from CO2 to create sucrose. Not just carbon dioxide, this enzyme sometimes catalyzes a areaction with oxygen from the air. When it does, it creates a toxic byproduct and wastes energy, making photosynthesis inefficient.

Professor of plant molecular biology at Cornell Maureen Hanson said, “You would like Rubisco to not interact with oxygen and to also work faster.”

In this research, scientists took the slow enzyme from tobacco plants and engineered it into E. coli. You may ask, “Why tobacco, though?” it turns out that this plant serves as a common model plant in research.

Hanson said, “We can now make mutations to try to improve the enzyme and then test it in E. coli.”

E. coli growing on Eosin methylene blue media. The bacteria looks pretty here. Photo by Gene Drendel Wikimedia Commons

And since E. coli is a type of bacteria that reproduce so rapidly, it proved to be advantageous to the researchers. They may test an altered Rubisco in these bacteria and get results the next day.

Before, another group of researchers attempted to engineer tobacco Rubisco into E. coli. That led to very weak expression of the enzyme.

In plants, Rubisco is composed of eight large and eight small subunits. A single gene encodes each large subunit, but many genes encode each small subunit. The complex process of enzyme assembly and the presence of multiple versions of the enzyme in plants has made it very hard to experiment with Rubisco.

But in the new paper, the researchers were able to break down the process and express a single type of large subunit and a single type of small subunit together in E. coli. They were also able to understand the enzyme’s properties. By doing this, they attained expression of the enzyme in E. coli that matched what was found in plants.

Another discovery is that a Rubisco subunit found in tiny hairs on plant leaves also worked faster than any of the subunits found in leaf cells.

“We now have the ability to engineer new versions of plant Rubisco in E. coli and find out whether the properties of an enzyme are better. Then, we can take the enzyme that’s improved and put that into a crop plant.”

At least there’s a good thing about E. coli. I mean, I know all bacteria has their own pros and cons, but what I know so far is that they’re no fun. Hopefully scientists can develop them further and make plants thrive more than ever.

 

Sources

https://www.sciencedaily.com/releases/2020/09/200929123555.htmhttps://www.sciencedaily.com/releases/2020/09/200921170505.htm

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