Harnessing a Plant's Food and Energy Potential

Summary

Plants are a major source of renewable, sustainable energy. They capture sunlight and then store it as the sugars, carbohydrates and cell structures from which biofuels are produced. In the process, they also “clean” CO2 out of the atmosphere. BTI scientists are working to explain the genetic workings that underlie the ability of plants to convert light energy into chemical energy and to absorb CO2. Still others are investigating how to make plants grow faster. This kind of research has important implications for helping to solve major environmental issues.

Peace, prosperity and security are directly related to the ability of all countries to be self-sufficient in food and energy and to slow global warming. Modern plant research carried out at institutions like BTI is critical to achieving these goals. BTI scientists are using the tools of modern molecular biology to study plant processes at the genetic level and uncover new ways to use plants for human advantage – as higher yielding food sources, as natural CO2 absorbers, and as biofeedstocks for the production of alternative fuels.

The Issue:

Prices at the gas pump are at historic highs. The ice caps are melting at an alarming rate. Food has increased in price worldwide by 83 percent in the last three years. It’s obvious that alternative energy sources must be found that are renewable and sustainable, burn cleaner than fossil fuels, and don’t depend on commodity foods, like corn, for their manufacture. It’s also obvious that to slow global warming we must find innovative ways to reduce the amount of carbon dioxide (CO2) already in the atmosphere.

It’s true that bioenergy derived from plants is not a “magic bullet,” and that plants alone cannot remove enough CO2 from the atmosphere to counteract the amount human activity adds everyday. Nonetheless, basic research in the areas of renewable energy and carbon fixation will play a key role in coming decades and will be a major focus of R&D investment. As a world leader in plant research, BTI is well-positioned to contribute knowledge that will make bioenergy affordable and sustainable, and may help lower CO2 levels. Following are summaries of three BTI research efforts in these areas.

Potential Impacts

Harnessing the sun

When the sun’s rays touch the surfaces of a plant, an amazing, highly efficient chemical reaction begins within the plant’s cells. This light-capturing reaction, called photosynthesis, uses the sun’s energy to convert carbon dioxide (CO2) and water into the sugars and carbohydrates the plant needs to grow and reproduce. Photosynthesis lies at the heart of a plant’s ability to “clean” CO2 out of the air. It’s also central to the growth of biomass – leaves, stems and seeds – required for the production of alternative fuels, like ethanol.

In two BTI research projects, our scientists are explaining the genetic factors that limit the amount of CO2 plants can absorb and discovering the genetic basis of photosynthesis in different kinds of plants. Both will lead to important new information with interesting practical applications.

• BTI’s President David Stern, Ph.D., is studying the molecular basis of CO2 absorption and what regulates it. It’s known that a certain enzyme produced in the plant’s chloroplasts (the cells that carry out photosynthesis) is key. When the chloroplasts are producing the enzyme, the plant absorbs CO2; when production of the enzyme stops, so does CO2 absorption. But, until recent discoveries in the Stern laboratory, no one knew how the production of this critical enzyme was regulated by the plant. Stern and his team have discovered how the plant turns the production of this enzyme on and off at the genetic level – a discovery that could one day enable scientists to override the enzyme shutdown process and produce plants that could clean even more CO2 out of the air than they do now. These plants should also yield more, so Stern’s research could result in a win-win for both the environment and for people – less CO2 in the atmosphere and more food on the table.
• Other research being done by Tom Brutnell, Ph.D., and his group is focused on understanding the molecular genetics of C4 carbon fixation. In this more efficient form of photosynthesis, plants use less nitrogen and water than are required for the more common C3 type of photosynthesis. C4 is the prevalent process among many prairie grasses and tropical crops, including corn, sugarcane, sorghum, millet, switchgrass and Miscanthus. His work to explain the molecular basis of C4 photosynthesis in corn and bioenergy grasses could lead to higher yielding crops for use as food and as ethanol biofeedstocks. Brutnell is also interested in switchgrass and Miscanthus as biofeedstocks because they grow quickly, they produce enormous amounts of plant material, and, most important, they are not food plants. His work on C4 photosynthesis could enhance the amount of biomass these grasses produce, making them a more efficient source of ethanol than corn and one that doesn’t compete with the food supply.

Life in the fast lane

If plants and trees could grow faster than they do now, they would more quickly and efficiently produce the biomass needed for the manufacture of alternative fuels. Faster growing trees would also speed reforestation and make tree farming for the production of paper products and lumber more lucrative.

To make trees grow more quickly, however, scientists need a better understanding of the genetic processes that promote growth. These processes depend on the ability of stem cells (cells that can become any kind of cell) to divide and differentiate into specialized cells, and form leaf, seed or other plant organs.

Solving this mystery is a goal of BTI scientist Ji-Young Lee, Ph.D. She is studying how stem cells in plant and tree roots produce the specialized cells, called xylem and phloem, that transport fluids throughout the plant and constitute a major part of plant biomass. Hundreds of candidate genes were identified, which might work in concert to coordinate the transformation of stem cells into xylem and phloem cells. Using this information and the latest biological and genetic techniques Lee is trying to understand the function of each of these genes and their regulatory network.

Currently, her work is concentrated on the Arabidopsis plant and the Populus tree, both commonly used for research purposes. What she learns about the genetic mechanisms that cause stem cells to divide and differentiate in these model systems will shed light on stem cell regulation in other, commercially important, plants and trees. With that knowledge, scientists may one day be able to influence the growth rate of trees and grasses, which could, in turn, increase the amount of biomass they produce for use as biofuel, feed or other purposes.