Taking the brakes off plant production: not so good after all

Reposted with kind permission from the MSU-DOE Plant Research Laboratory. Original article.

By: Igor Houwat, Atsuko Kanazawa, David Kramer

The need for speed: increasing plant yield is one way to increase food and fuel resources. But asking plants to simply do more of the usual is a strategy that can backfire. Photo by Romain Peli on Unsplash

When engineers want to speed something up, they look for the “pinch points”, the slowest steps in a system, and make them faster.

Say, you want more water to flow through your plumbing. You’d find the narrowest pipe and replace it with a bigger one.

Many labs are attempting this method with  photosynthesis, the process that plants and algae use to capture solar energy.

All of our food and most of our fuels have come from photosynthesis. As our population increases, we need more food and fuel, requiring that we improve the efficiency of photosynthesis.

But, Dr. Atsuko Kanazawa and the Kramer Lab are finding that, for biological systems, the “pinch point” method can potentially do more harm than good, because the pinch points are there for a reason!  So, how can this be done?

 

ATP synthase: an amazing biological nanomachine

Atsuko and her colleagues at the MSU-DOE Plant Research Laboratory (PRL) have been working on this problem for over 15 years. They have focused on a tiny machine in the  chloroplast called the  ATP synthase, a complex of proteins essential to storing solar energy in “high energy molecules” that power life on Earth.

That same ATP molecule and a very similar ATP synthase are both used by animals, including humans, to grow, maintain health, and move.

In plants, the ATP synthase happens to be one of the slowest process in photosynthesis, often limiting the amount of energy plants can store.

Photosynthetic systems trap sunlight energy that starts the reaction to move electrons forward in an assembly-line fashion to make useful energy compounds. The ATP synthase is one of the “pinch points” that slows the flow as needed, so plants stay healthy. In cfq, the absence of feedback leads to an electron pile up at PSI, and a crashed system. By MSU-DOE Plant Research Laboratory, except tornado graphic/CC0 Creative Commons

 

Kicking up the gears of plant production

Atsuko thought, if the ATP synthase is such an important pinch point, what happens if it were faster? Would it be better at photosynthesis and give us faster growing plants?

Years ago, she got her hands on a mutant plant, called cfq, from a colleague. “It had an ATP synthase that worked non-stop, without slowing down, which was a curious example to investigate. In fact, under controlled laboratory conditions – very mild and steady light, temperature, and water conditions – this mutant plant grew bigger than its wild cousin.”

But when the researchers grew the plant under the more varied conditions it experiences in real life, it suffered serious damage, nearly dying.

“In nature, light and temperature quality change all the time, whether through the passing hours, or the presence of cloud cover or winds that blow through the leaves,” she says.

 

Plants slow photosynthesis for a reason!

Recent innovations from the Kramer lab are enabling Atusko and her colleagues to probe into how real environmental conditions affect plant growth.

Atsuko’s research now shows that the slowness of the ATP synthase is not an accident; it’s an important braking mechanism that prevents photosynthesis from producing harmful chemicals, called reactive oxygen species, which can damage or kill the plant.

“It turns out that sunlight can be damaging to plants,” says Dave Kramer, Hannah Distinguished Professor and lead investigator in the Kramer lab.

“When plants cannot use the light energy they are capturing, photosynthesis backs up and toxic chemicals accumulate, potentially destroying parts of the photosynthetic system. It is especially dangerous when light and other conditions, like temperature, change rapidly.”

“We need to figure out how the plant presses on the brakes and tune it so that it responds faster…”

The ATP synthase senses these changes and slows down light capture to prevent damage. In that light, the cfqmutant’s fast ATP is a bad idea for the plant’s well-being.

“It’s as if I promised to make your car run faster by removing the brakes. In fact, it would work, but only for a short while. Then things go very wrong!” Dave says.

“In order to improve photosynthesis, what we need is not to remove the brakes completely, like in cfq, but to control them better,” Dave says. “Specifically, we need to figure out how the plant presses on the brakes and tune it so that it responds faster and more efficiently,” David says.

Atsuko adds: “Scientists are trying different methods to improve photosynthesis. Ultimately, we all want to tackle some long-term problems. Crucially, we need to continue feeding the Earth’s population, which is exploding in size.”

The study is published in the journal, Frontiers in Plant Science.

 

Potatoes, allies on Earth and on Mars

By
Zoraida Portillo (Perú)

[LIMA] A joint initiative between NASA and the International Potato Centre (CIP), which is based in Peru, offers scientific evidence that it is possible to grow at least four types of potatoes on Mars.

A scenario starring the root crop was portrayed in the movie “The Martian” (2015), in which a lost astronaut, played by Matt Damon, survives on potatoes he cultivates on the red planet while awaiting rescue.

But in addition to this interplanetary possibility, scientists also observed the crop is genetically suited to adapting to the changes creating more adverse environmental conditions on Earth.

So before turning fiction into reality, the tuber has a mission on Earth.

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In the movie “The Martian”, Matt Damon survives eating the potatoes he cultivates on Martian soil. Credit: 20th Century Fox.

The hardy potato quartet
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Scientists have studied 65 types of potatoes and have identified four that could grow successfully on Martian soil. Credit: International Potato Center / Mars Project

The study has identified four types of potatoes, out of 65 examined, which have shown resistance to high salinity conditions and were able to form tubers in a type of soil similar to that on Mars.
One of these is the Tacna variety, developed in Peru in 1993. It was introduced to China shortly afterwards, where it showed high tolerance to droughts and saline soils with hardly any need for irrigation.

This variety became so popular in China that it was ‘adopted’ in 2006 under the name of Jizhangshu 8. The same high tolerance was seen on the saline and arid soils of Uzbekistan, a country with high temperatures and water shortages, where the variety was also introduced and renamed as Pskom.

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In China, the Peruvian Tacna potato variety was renamed Jizhangshu 8. Credit: International Potato Center 

The second variety that passed the salinity test is being cultivated in coastal areas of Bangladesh that have high salinity soils and high temperatures. The other two types are promising clones — potatoes that are being tested for attributes that would make them candidates for becoming new varieties.

These four potato types were created as a result of the CIP’s breeding programme to encourage adaptation to conditions in subtropical lowlands, such as extreme temperatures, which are expected to be strongly affected by climate change.

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Women harvest resistant potatoes in saline soils in Bangladesh. Credit: International Potato Center

Down to Earth

In addition to these four potato ‘finalists’, other clones and varieties have shown promising results when tested in severe environmental conditions. The findings offer researchers new clues about the genetic traits that can help tubers cope with severe weather scenarios on Earth.

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Walter Amorós, CIP’s potato breeder is one of the five researchers involved in the project. Credit: Zoraida Portillo

“It was a pleasant surprise to see that the potatoes that we have improved to tolerate adverse conditions were able to produce tubers on this soil [soil similar to that on Mars],” says Walter Amorós, CIP potato breeder and one of the five researchers involved in the project, who has studied potatoes for more than 30 years.

According to Alberto García, adviser to the UN Food and Agriculture Organization in Peru who is in charge of food security programmes, this experiment “serves to verify that potato, a produce of great nutritional value, is a crop extremely adaptable to the worst conditions”, something that is very relevant for current climate scenarios.

García stresses that global temperatures are now rising at a rate higher than expected, affecting not only potatoes but also other crops. Many now need to be cultivated at higher altitudes — which, he says, is not always a disadvantage and may even be beneficial for crops that were previously cultivated in valleys.

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Credit: Zoraida Portillo

“But it can also have negative consequences that we have to anticipate,” adds García. Therefore, he says this experiment can inspire others to think about future scenarios and look for other crops than can adapt to extreme conditions that will have an impact on agriculture.

Similar to Mars

The project began with a search for soils similar to that found on Mars. Julio Valdivia-Silva, a Peruvian researcher who worked at NASA’s Ames Research Center, eventually concluded that the soil samples collected in the Pampas de la Joya region of southern Peru were the most similar to Martian soil.

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Julio Valdivia-Silva took soil samples at Pampa de La Joya, Peru. Credit: NASA/ International Potato Center

Arid, sterile and formed by volcanic rocks, these soil samples were extremely saline.

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Credit: Pampas de La Joya Official Site

 

Helped by engineers from the University of Engineering and Technology (UTEC) in Lima and based on designs by NASA’s Ames Research Center, the CIP built CubeSat — a miniature satellite that recreates, in a confined environment, a Martian-like atmosphere. This is where the potatoes were cultivated.

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The varieties were cultivated inside CubeSat, built by the CIP to recreate environmental conditions similar to those on Mars. Credit: International Potato Center / Mars Project

“If potatoes could tolerate the extreme conditions to which we exposed them in our CubeSat, they have a good opportunity to develop on Mars,” says Valdivia-Silva.

They then conducted several rounds of experiments to find out which varieties could better withstand the extreme conditions, and what minimum conditions each crop needed to survive.

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La Joya desert, Peru (left); Martian soil (right). Credits: Pampas de La Joya Official Site and NASA, respectively.

CubeSat, hermetically sealed, housed a container with La Joya soil, where each one of the tubers was cultivated. CubeSat itself supplied water and nutrients, controlled the temperature according to that expected at different times on Mars, and also regulated the planet’s pressure, oxygen and carbon dioxide levels.

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Connected to a computer, the CubeSat supplied water and nutrients, and imitated other environmental conditions that would be found on Mars. Credit: International Potato Center / Mars Project

 

Cameras were installed to record the process, broadcasting developments on the soil and making it possible to see the precise moment in which potatoes sprouted.

Based on the results, CIP scientists say that in order to grow potatoes on Mars, space missions will have to prepare the soil so it has a loose structure and contains nutrients that allow the tubers to obtain enough oxygen and water.

In a next phase of the project, the scientists hope to expose successful varieties to more extreme environmental conditions. This requires, among other things, developing a prototype satellite similar to CubeSat that can replicate more extreme conditions with greater precision, at a price tag of US$ 100,000.

This piece was produced by SciDev.Net’s Latin America and Caribbean desk.

This article was originally published on SciDev.Net. Read the original article.