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With A Genetic Tweak, Crops That Grow 40 Percent Larger

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tractor spraying crops

(Credit: Fotokostic/Shutterstock)

What if your ability to feed yourself was dependent on a process that made a mistake 20 percent of the time?

We face this situation every day. That’s because the plants that produce the food we eat evolved to solve a chemistry problem that arose billions of years ago. Plants evolved to use carbon dioxide to make our food and the oxygen we breathe – a process called photosynthesis. But they grew so well and produced so much oxygen that this gas began to dominate the atmosphere. To plants, carbon dioxide and oxygen look very similar, and sometimes, plants use an oxygen instead of carbon dioxide. When this happens, toxic compounds are created, which lowers crop yields and costs us 148 trillion calories per year in unrealized wheat and soybean yield – or enough calories to feed an additional 200 million people for a whole year.

Improving crop yields to grow more food on less land is not a new challenge. But as the global population grows and diets change, the issue is becoming more urgent. It seems likely that we will have to increase food production by between 25 and 70 percent by 2050 to have an adequate supply of food.

As a plant biochemist, I have been fascinated by photosynthesis for my whole career, because we owe our entire existence to this single process. My own interest in agricultural research was spurred by this challenge: Plants feed people, and we need to quickly develop solutions to feed more people.

tobacco plants

Amanda Cavanagh tests modified tobacco plants in a specialized greenhouse to select ones with genetic designs that boost the yield of key food crops. (Credit: Claire Benjamin/RIPE Project, CC BY-ND)

Supercharging Photosynthesis to Grow More Food

It can take decades for agricultural innovations such as improved seeds to reach growers’ fields, whether they are created via genetic approaches or traditional breeding. The high-yielding crop varieties that were bred during the first green revolution helped prevent food shortages in the 1960s by increasing the proportion of grain-to-plant biomass. It’s the grain that contains most of the plant’s consumable calories, so having more grain instead of straw means more food. But most crops are now so improved that they are close to their theoretical limit.

I work on an international project called Realizing Increased Photosynthetic Efficiency (RIPE), which takes another approach. We are boosting harvests by increasing the efficiency of photosynthesis – the solar-powered process that plants use to turn carbon dioxide and water into greater crop yields. In our most recent publication, we show one way to increase crop yield by up to 40 percent by rerouting a series of chemical reactions common to most of our staple food crops.

Photorespiration Costs a Lot of Energy

Two-thirds of the calories we consume across the globe come directly or indirectly from just four crops: rice, wheat, soybean and maize. Of these, the first three are hindered by a photosynthetic glitch. Typically the enzyme that captures carbon dioxide from the atmosphere, called Rubisco, converts carbon dioxide into sugar and energy. But in one out of every five chemical reactions, Rubisco makes a mistake. The enzyme grabs an oxygen molecule instead. Rather than producing sugars and energy, the chemical reaction yields glycolate and ammonia, which are toxic to plants. To deal with this problem, plants have evolved an energy-expensive process called photorespiration that recycles these toxic compounds. But toxin recycling requires so much energy that the plant produces less food.

photosynthesis

In the process of photosynthesis, carbon dioxide and water are transformed into sugars and oxygen. Sunlight powers this chemical reaction. (Credit: BlueRingMedia/Shutterstock)

Photorespiration uses so much energy that some plants, like maize, as well as photosynthetic bacteria and algae, have evolved mechanisms to prevent Rubisco’s exposure to oxygen. Other organisms, like bacteria, have evolved more efficient ways to remove these toxins.

These natural solutions have inspired many researchers to try to tweak photorespiration to improve crop yields. Some of the more efficient naturally occurring recycling pathways have been genetically engineered in other plants to improve growth and photosynthesis in greenhouse and laboratory conditions. Another strategy has been to modify natural photorespiration and speed up the recycling.

Chemical detour improves crop yield

photosynthesis pathway

The red car represents unmodified plants who use a circuitous and energy-expensive process called photorespiration that costs yield potential. The blue car represents plants engineered with an alternate route to shortcut photorespiration, enabling these plants to save fuel and reinvest their energy to boost productivity by as much as 40 percent. (Credit: RIPE, CC BY-SA)

These direct manipulations of photorespiration are crucial targets for future crop improvement. Increased atmospheric carbon dioxide from fossil fuel consumption boosts photosynthesis, allowing the plant to use more carbon. You might assume that that this will solve the oxygen-grabbing mistake. But, higher temperatures promote the formation of toxic compounds through photorespiration. Even if carbon dioxide levels more than double, we expect harvest yield losses of 18 percent because of the almost 4 degrees Celsius temperature increase that will accompany them. We cannot rely on increasing levels of carbon dioxide to grow all the food we will need by 2050.

I worked with Paul South, a research molecular biologist with the U.S. Department of Agriculture, Agricultural Research Service and professor Don Ort, who is a biologist specializing in crop science at the University of Illinois, to explore whether modifying the chemical reactions of photorespiration might boost crop yields. One element that makes recycling the toxin glycolate so inefficient is that it moves through three compartments inside the plant cell. That’s like taking an aluminum can into three separate recycling plants. We engineered three new shortcuts that could recycle the compound in one location. We also stopped the natural process from occurring.

modified plants experiment

Four unmodified plants (left) grow beside four plants (right) engineered with alternate routes to shortcut photorespiration. The modified plants are able to reinvest their energy and resources to boost productivity by 40 percent. (Credit: Claire Benjamin/RIPE Project, CC BY-ND)

Designed in Silico; Tested in Soil

Agricultural research innovations can be rapidly tested in a model species. Tobacco is well-suited for this since it is easy to genetically engineer and grow in the field. The other advantage of tobacco is that it has a short life cycle, produces a lot of seed and develops a leafy canopy similar to other field crops so we can measure the impact of our genetic alterations in a short time span. We can then determine whether these modifications in tobacco can be translated into our desired food crops.

We engineered and tested 1,200 tobacco plants with unique sets of genes to find the genetic combination that recycled glycolate most efficiently. Then we starved these modified plants of carbon dioxide. This triggered the formation of the toxin glycolate. Then we identified which plants grew best – these have the combination of genes that recycled the toxin most efficiently. Over the next two years, we further tested these plants in real-world agricultural conditions. Plants with the best combination of genes flowered about a week earlier, grew taller and were about 40 percent larger than unmodified plants.

Field Trials

Over two years of field trials, scientists Donald Ort (right), Paul South (center) and Amanda Cavanagh (left) found tobacco plants engineered to modify photorespiration are more productive in real-world field conditions. Now they are translating this technology hoping to boost the yield of key food crops, including soybeans, rice, cowpeas and cassava. (Credit: Claire Benjamin/RIPE Project, CC BY-ND)

Having shown proof of concept in tobacco, we are beginning to test these designs in food crops: soybean, cowpea, rice, potato, tomato and eggplant. Soon, we will have a better idea of how much we can increase the yield of these crops with our modifications.

Once we demonstrate that our discovery can be translated into food crops, the Food and Drug Administration and the USDA will rigorously test these modified plants to make sure they are safe for human consumption and pose no risk to the environment. Such testing can cost as much as US$150 million and take more than 10 years.

Since the process of photorespiration is common across plant species, we are optimistic that our strategy will increase crop yields by close to 40 percent and help find a way to grow more food on less land to be able to feed a hungry global population by 2050.

 

Amanda Cavanagh, Postdoctoral Research Associate at the Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign

This article is republished from The Conversation under a Creative Commons license. Read the original article.

The Conversation

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Ecology

Yukon and Northern BC First Nations tackle climate change using Indigenous knowledge and science

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YUKON, June 18, 2021 /CNW/ – The Government of Canada is working together in partnership with Indigenous and Northern communities in finding solutions to adapt to the impacts of climate change in the North.

Today, Minister of Northern Affairs, Daniel Vandal, along with Parliamentary Secretary to the Minister of Economic Development and Official Languages (Canadian Northern Economic Development Agency), Larry Bagnell, highlighted progress on three unique, Indigenous-led projects that are helping communities in Yukon and Northern British Columbia adapt to the challenges posed by climate change.

The Minister and Parliamentary Secretary met virtually with Carcross/Tagish First Nation (C/TFN) to learn about their community-led climate change monitoring program. C/TFN has partnered with Tsay Keh Dene Nation (TKDN) and Chu Cho Environmental of Prince George, British Columbia, to build a community-led monitoring project that examines environmental data and Indigenous knowledge to create a holistic picture of how the climate is changing across C/TFN and TKDN traditional territories. The project combines tracking of current and historical climate trends with knowledge shared by Elders while also providing opportunities for youth mentorship and climate change awareness.

The Taku River Tlingit First Nation (TRTFN) is also leading a unique project to assess the impacts of climate change within their traditional territory. Climate change is causing many of the culturally significant ice patches to melt, exposing organic artifacts to oxygen and leading to rapid deterioration. The TRTFN ice patch mapping project will involve performing archaeological assessments to prevent the degradation of artifacts. Research will be guided by traditional knowledge, Elders and oral histories, when available, and heavily involve community, Elders, youth and Knowledge Keepers.

The Pelly Crossing Selkirk Development Corporation is leading the Selkirk Wind Resource Assessment project through the installation of a Sonic Detection and Ranging (SODAR) system. The initiative includes a feasibility study leading up to the construction of a renewable energy facility, including wind, solar and battery energy storage. Expanding clean energy within the region will have direct benefits for communities, including reduced reliance on diesel, job creation and revenue generation for Selkirk First Nation. 

These projects are delivering important environmental, social and economic benefits that lead to healthier, more sustainable and resilient communities across Yukon and Northern British Columbia. They also build community clean energy capacity and help to avoid the impacts of climate change.

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Ecology

Atlantic Provinces Ready For Aquaculture Growth

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Aquaculture is an important economic driver for rural, coastal and Indigenous communities, and Atlantic Canada is well positioned to increase aquaculture production as global demand for sustainably sourced seafood grows.

That is why the ministers responsible for aquaculture in the Atlantic provinces have agreed to the ongoing development and management of their industries based on common principles. A new memorandum of understanding has been signed by the four ministers, which extends the previous agreement signed in 2008.

“In a time when food security is especially important, it is good to see our aquaculture industry has grown steadily and is poised for continued growth in 2021 based on environmentally responsible, science-based policies and practices,” said Keith Colwell, Minister of Fisheries and Aquaculture for Nova Scotia. “Our Atlantic partnership continues to help the industry grow sustainably.”

Cooperation between the provinces and the aquaculture industry has led to improvements in pest management, environmentally sustainable aquaculture methods, aquatic animal health and policies to support the shared use of marine and freshwater resources. It also aims to align regulation and policy between the provinces to make the regulatory requirements easier to understand by industry and the public.

Each province has a comprehensive and robust legislative and regulatory framework to ensure environmental sustainability, economic prosperity and public accountability. The provinces update their legislation and regulations regularly. Nova Scotia revamped its regulatory framework in 2015; New Brunswick received Royal Assent for a new Aquaculture Act in 2019 and is working on the supporting regulations; Newfoundland and Labrador completely revised its aquaculture policy in 2019; and Prince Edward Island has recently drafted a new Aquaculture Act.

The ministers have agreed to continue to use science-based evidence for management decisions, thereby increasing public and investor confidence in the Atlantic Canadian aquaculture industry.

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Ecology

COMING SOON: A Healthy Environment and a Healthy Economy 2.0

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We all want the same thing: a clean and responsible energy future for our children and future generations while continuing to enjoy a high standard of living.

On December 11, 2020, the Prime Minister announced a new climate plan which he claimed will help achieve Canada’s economic and environmental goals.

The proposed plan by Environment and Climate Change Canada (ECCC) entitled “A Healthy Environment and a Healthy Economy” will have an initial investment of $15 billion of taxpayer’s money. It is built on 5 pillars of action:

  1) Making the Places Canadians Live and Gather More Affordable by Cutting Energy Waste

2) Making Clean, Affordable Transportation and Power Available in Every Community

3) Continuing to Ensure Pollution isn’t Free and Households Get More Money Back

4) Building Canada’s Clean Industrial Advantage

5) Embracing the Power of Nature to Support Healthier Families and More Resilient Communities  

In my paper, “A Healthy Environment and a Healthy Economy 2.0” I will objectively critique each pillar in the government’s new climate plan and provide alternative solutions to the same issues.

  This is an alternative plan that supports workers, protects lower income earners and creates economic growth while respecting the environment and focusing on the dignity of work.

  This plan abandons virtue-signaling projects and relies on Canadian ingenuity to build our economy and restore Canada’s role of responsible leadership in the world.

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