Tuesday , July 27 2021

Newly discovered cold-resistant plants from Siberia could promote clean bioenergy

Climate change is an urgent threat to societies around the world caused by carbon dioxide emissions from fossil fuels such as oil. One of the most effective ways to limit emissions is to replace these energy sources with others that are carbon neutral or even carbon-negative – that is, technologies that remove more carbon dioxide from the atmosphere than they bring.

Bioenergy or energy obtained from organic matter, usually plants, is an attractive option. The United States is already recovering 5% of the transport fuel from bioenergy, mostly maize. Even jet fuel can be produced from specially designed crops, potentially able to balance 3% of human production.

As the world population and its demand for food continue to grow, there may not be enough conventional farmland for growing crops for both food and bioenergy. One solution is to grow bioenergy crops that are not good enough for food production. Logical conundrum: If this soil is not good, how can we grow up everything that is reasonably productive?

Eric Sachs in front of the 11.5-foot stand Miscanthus x giganteus at the University of Illinois Energy Farm. This stand is latent in winter, but in spring it will again release green leaves.
Claire Benjamin / University of Illinois, CC BY-SA

Miscanthus, candidate bioenergy culture

This is the place Miscanthus x -Global This species, also known as ivory, is incredibly productive – 59% more productive than midwestern corn. It grows well on peripheral soils with minimal fertilization. M. x -Global is perennial, which means that it stores nutrients in the underground stems called rhizomes and uses them for recovery from one year to the next. These rhizomes, together with the roots of the plant, store the atmospheric carbon dioxide underground and keep the soil in place, preventing the loss of carbon dioxide from erosion. M. x -Global may be able to maintain a significant amount of bioenergy production to replace fossil fuels, while being grown on land that does not compete with food crops.

M. x -Global is a natural hybrid: although it performs well in experimental studies, it has never been designed to be a bioenergy culture. It is produced by crossing the Asian grasses Miscanthus sacchariflorus and Miscanthus sinensispopular ornamental plants whose flowers form beautiful feathers. M. x -Global is sterile and can only be distributed cloned – that is, instead of seeds, a rhizome of a M. x -Global the plant may grow into a new, genetically identical plant. One clone of this hybrid, now called "Illinois", is the focus of most trials Miscanthus as a bioenergy culture in Europe and the United States

The incredible productivity and sustainability of the Illinois clone, especially after the first US agronomic testing at the University of Illinois in 2000, M. x -Global as the leading bioenergy candidate. But the Illinois clone was produced by accident. What if the parent species M. sacchariflorus and M. sinensis, growing in the wild in Asia, had even more endurance that could be used by scientists in breeding plants M. x -Global hybrids that perform even better than Illinois?

Miscanthus, mosquitoes and colder tolerance

I'm a physiologist at the University of Illinois at Urbana-Champaign. My work includes understanding how plants work to develop improved crops that can mitigate climate change, in this case by developing improved hybrids of M. x -Global for the production of bioenergy. I got together with Professor Eric Sachs to explore some of the plants he had recently collected during a trip to eastern Siberia.

In the summer of 2016, Sacks's team of fearless plant scientists, led by two adventurous ecotourist leaders, transformed amateur botanists to overcome flooding and mosquitoes from East Siberia to collect one of the world's largest collections of M. sacchariflorus plants. The team is interested in harvesting plants that can withstand the cold better than M. x -Global Illinois, which fights for photosynthesis, a process where plants use sunlight to capture carbon dioxide from the air and turn it into biomass when the temperature drops below 50 degrees Fahrenheit.

Eastern Siberia is the coldest part of the world where Miscanthus grows. A kind of, M. sacchariflorus, was found to grow in areas with a minimum temperature of October to 26 ° F, compared with 41 ° F in central Illinois. Most of the plant harvesting area has a continental climate with heavy winters and high temperature fluctuations in spring and autumn, suggesting that these plants can thrive over a wide temperature range.

With this diverse Siberian collection containing 181 connections or groups of genetically related plants, Idan Spitz and myself, physiologists from Professor Stephen Long's laboratory, we decided to look for M. sacchariflorus with extreme tolerance to photosynthesis to cold conditions. These cold-tolerant samples can then be returned to the US and used to grow a more cold-resistant and therefore more productive, M. x -Global,

Among them is Eric Sachs Miscanthus sacchariflorus in eastern Siberia.
Eric Sachs, CC BY-SA

Of many, three

We filtered out 181 genetically different Siberian connections to a handful showing the greatest photosynthetic tolerance to cold. To identify the best cold-adapted plants, the entire collection was grown outdoors at the University of Aarhus, Denmark. M. x -Global "Illinois" was being grown as a control. During cold weather when temperatures drop below 54 ° F, we measured the fluorescence of leaves of individual plants to identify those that were least marked by these low temperatures. Fluorescence is the minimum amount of light emitted by the key components of the leaf and can be measured to detect when the leaf has been damaged.

Sheet of Miscanthus is placed in the camera of a tool that measures photosynthesis.
Don Hammerman, CC BY-SA

We brought the most promising M. sacchariflorus plants to the University of Illinois to grow together with M. x -Global Illinois in a closed environment with precisely controlled light, temperature and humidity. In two successive experiments we regularly observed photosynthesis, as the plants were subjected to strong cooling at 50 ° F for two weeks. Then we increased the temperature to see how well they can recover. Our team measures photosynthesis by tracking the absorption of carbon dioxide in the leaves of the surrounding air.

Although photosynthesis slowed down Miscanthus plants during cooling, we were excited to find three genetically unique ones M. sacchariflorus specimens that have maintained much better activity during the cold than M. x -Global – Illinois. The first kept the rate of photosynthesis doubled by that of M. x -Global "Illinois"; the latter quickly restores photosynthesis when temperature increases, a useful feature that can maximize photosynthesis during periodic warm periods in early spring. Third stabilized photosynthesis during cooling; in contrast, photosynthesis in the Illinois clone has steadily decreased over the two weeks.

IN Miscanthus the plants studied here, improved photosynthesis during cooling is supported by the ability to maintain the activity of photosynthetic enzymes that are essential for the absorption of carbon dioxide by the atmosphere but slow down at lowering temperatures. M. x -Global Illinois adapts to the cold by producing more of these enzymes to counteract cooling. The new one M. sacchariflorus The plants we found in Siberia may be even better at producing these enzymes at low temperature.

What next?

Identifying these useful features is only the first step. Then, scientists at the University of Illinois will use these three genetically unique approaches to growing new hybrids M. x -Global who perform better in the cold. Through propagation Miscanthus with improved photosynthesis during the cool of early spring and late autumn, we can develop new hybrids that give more than M. x -Global "Illinois".

Additional, Miscanthus is a close relative of sugar cane, so Saxy is bred to Siberians M. sacchariflorus specimens with sugar cane to develop cultivated energy plants that can grow further north of current US sugar; Currently, sugar cane production is limited to the southern parts of Florida, Louisiana and Texas. The goal is to create new bioenergy crops that can withstand low temperatures to produce more biomass and, ultimately, more bioenergy.

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