Climate change is an urgent threat for companies around the world because of carbon dioxide emissions from fossil fuels such as oil. One of the most effective ways to reduce emissions is to replace these energy sources with other carbon-neutral or even carbon-neutral ones, that is, energy sources. technologies that remove more carbon dioxide from the atmosphere than they produce.
Bioenergy, or energy derived from organic matter, usually plants, is an attractive option. The United States already derives five percent of its transportation fuel from bioenergy, mainly corn. Even jet fuel could be produced from specially designed crops, potentially offsetting three per cent of the world's man-made emissions.
As the world's population and demand for food continues to increase, there is a risk that conventional farmland may be insufficient to grow crops for both food and bioenergy. One solution is to grow bioenergy crops on marginal lands, which is not enough to produce food. The logical conundrum: if this soil is not good, how can we cultivate something that is reasonably productive?
Miscanthus, the candidate bioenergy culture
That's where Miscanthus X giganteus enter. This species, also known as elephant grass, is incredibly productive – 59 percent more productive than corn in the US Midwest. It grows well on marginal soils with minimal fertilization. Mr. X giganteus is a perennial plant, which means that it stores nutrients in underground stems called rhizomes and uses them to regrow from one year to the next. These rhizomes, along with the roots of the plant, store atmospheric carbon dioxide in the soil and hold the soil in place, preventing the loss of carbon dioxide from erosion. Mr. X giganteus may be able to maintain significant bioenergy production to replace fossil fuels, while being grown on marginal lands that do not compete with food crops.
Mr. X giganteus is a natural hybrid: despite good results in experimental trials, it was never designed to be a bioenergetic crop. It is produced by crossing Asian herbs Miscanthus sacchariflorus and Miscanthus sinensis, popular ornamental plants whose flowers form beautiful plumes of feathers. Mr. X giganteus is sterile and can only be propagated by cloning, that is, it is a rhizome derived from a Mr. X giganteus plant can become a new genetically identical plant. A single clone of this hybrid, now called "Illinois", has been the subject of most Miscanthus bioenergy in Europe and the United States
The incredible productivity and resilience of the "Illinois" clone, particularly since the first US agronomic trials conducted at the University of Illinois in 2000, propelled Mr. X giganteus to prominence as a leading candidate bioenergy culture. Yet the "Illinois" clone was accidentally produced. And if the parent species M. sacchariflorus and M. sinensis, growing wild in Asia, had an even greater resilience, which plant scientists could use to Mr. X giganteus Hybrids even better than "Illinois"?
Miscanthus, mosquitoes and more cold tolerance
I am a Plant Physiologist at the University of Illinois at Urbana-Champaign. My job is to understand how plants work to develop improved crops that can mitigate climate change, in this case by developing improved hybrids of Mr. X giganteus for bioenergy production. I teamed up with Professor Erik Sacks to study some of the plants that he had recently collected during a trip to eastern Siberia.
In the summer of 2016, the team of intrepid scientists Sacks, led by two adventurous ecotourism guides who became amateur botanists, braved the floods and mosquitoes of eastern Siberia to gather one of the most important collections of M. sacchariflorus plants. The team was interested in collecting plants that could withstand the cold better than Mr. X giganteus "Illinois", which fights for photosynthesis, a process in which plants use sunlight to capture carbon dioxide from the air and turn it into biomass when temperatures drop below 50 degrees Fahrenheit.
Eastern Siberia is the coldest part of the world where Miscanthus grows. A species, M. sacchariflorus, was found growing in areas where the minimum temperature in October was as low as 26 ° F compared to 41 ° F in central Illinois. Most of the areas where plants were collected had a continental climate, with severe winters and strong temperature changes in spring and autumn, suggesting that these plants can thrive in a wide range of temperatures.
With this diverse collection of Siberia, containing 181 accessions, or groups of genetically related plants, Idan Spitz and I, plant physiologists from Professor Stephen Long's laboratory, have decided to look for M. sacchariflorus with exceptional tolerance of cold photosynthesis. These cold-tolerant specimens could then be brought back to the United States and used to grow more cold-tolerant and therefore more productive. Mr. X giganteus.
From several, three
We filtered 181 genetically distinct accessions from Siberia up to a handful displaying the greatest photosynthetic cold tolerance. To identify the plants best adapted to the cold, the entire collection was grown in an open field at the University of Aarhus, Denmark. Mr. X giganteus "Illinois" was developed next as a control. During a cold snap, when temperatures dropped below 15 ° C (54 ° F), we measured leaf fluorescence on individual plants to identify which ones were the least stressed by these low temperatures. Fluorescence is a tiny amount of light emitted by the key components of the sheet and can be measured to detect when the leaf is damaged.
We brought the most promising M. sacchariflorus plants at the University of Illinois to grow with Mr. X giganteus "Illinois" in an indoor environment with light, temperature and humidity precisely controlled. In two successive experiments, we regularly monitored photosynthesis because the plants were exposed to intense cooling at 50 ° F for two weeks. We then increased the temperature to check how far they could recover. Our team measured photosynthesis by monitoring the uptake of carbon dioxide into the leaf by ambient air.
Although photosynthesis has slowed down in all Miscanthus plants during the cooling, we were delighted to discover three genetically unique M. sacchariflorus specimens that had a much better activity during the cold than Mr. X giganteus "Illinois". The first maintained photosynthesis rates twice that of Mr. X giganteus "Illinois"; the second quickly recovers photosynthesis as temperatures increase, a useful capacity that can maximize photosynthesis during warm, intermittent periods in early spring. The third stabilized photosynthesis during cooling; In contrast, photosynthesis in the "Illinois" clone decreased steadily over the two weeks.
in the Miscanthus plants studied here, the improvement of photosynthesis during cooling is supported by the ability to maintain the activity of photosynthetic enzymes that are essential for the absorption of carbon dioxide from the atmosphere but slow down when temperatures drop. Mr. X giganteus "Illinois" adapts to the cold by producing more of these enzymes to fight the cold. New M. sacchariflorus The plants we found in Siberia could be even better to increase the production of these enzymes at low temperatures.
Identifying these useful traits is only the first step. Scientists from the University of Illinois will then use these three genetically unique accessions to create new hybrids of Mr. X giganteus that work best in the cold. Breeding Miscanthus with improved photosynthesis during the cool temperatures of early spring and late fall, we can develop new hybrids that give even more than Mr. X giganteus "Illinois."
In addition, Miscanthus is a close relative of sugar cane, so Sacks raises Siberia M. sacchariflorus specimens containing sugar cane to develop energy lignite cultivars that can be grown further north than the current commercial sugar cane in the United States – currently, sugarcane production is limited to southern Florida, Louisiana and Texas. The goal is to create new bioenergy crops that can withstand cold temperatures to produce more biomass and, ultimately, more bioenergy.
Charles Pignon, Postdoctoral Research Associate, University of Illinois at Urbana-Champaign
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