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Plant biology blasts off: Shuttle missions explore biofuels

Erin Podolak

Researchers are utilizing NASA’s last space shuttle missions to conduct research on jatropha-based biofuels to potentially improve their usage on Earth.

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During the their most recent missions, The National Aeronatics and Space Association (NASA) space shuttles have carried with them components of an experiment that may give researchers the genetic insights that they need to produce cleaner, cheaper biofuels from the jatropha plant.

Jatropha curcas, found in warm-temperate regions, is of interest to biofuel researchers since the oil from its seeds can be processed for use in a standard diesel engine. Indeed, some airlines have already experimented with jatropha-based biofuels to power their jet planes, but using the plant to support America’s roadways has hit a major roadblock: growers have struggled to cultivate it on a large-enough scale for mass production.

But now, researchers from the University of Florida (UF) believe that they can determine the genes needed to enable the mass production of jatropha—by sending the plant's cells into space.

In a previous study, the group’s UF colleagues Anna-Lisa Paul and Robert Ferl of the Department of Horticultural Sciences found that a microgravity environment can alter gene expression. Paul found that 182 genes in the plant Arabidopsis thaliana were expressed differentially in response to spaceflight, including genes related to heat shock.

Jatropha curcas. Source: Wagner Vendrame for the University of Florida.

The new jatropha group, led by UF associate professor of horticulture Wagner Vendrame, wants to determine which genes are responsible for temperature regulation in jatropha, so that the plant could be genetically modified for large scale cultivation in varying climates. “For the widespread cultivation of jatropha, a tropical plant, adaptation to specific climate and soil conditions is essential,” Vendrame told BioTechniques. “For example, cold tolerance is a major goal for growing jatropha commercially in the US. Other genes of interest, such as those involved in oil production in the seed—and any other stress-related genes that could confer some type of tolerance or resistance—would also be of value.”

NASA was interested in supporting the jatropha experiment because the research will utilize the International Space Station National Laboratory (ISS-NL), for this high-profile research that could affect consumers on Earth. “The premise is the use of basic research towards the development of products of value, which can only be developed or optimized in microgravity,” said Vendrame. “The success of our project opens new windows for similar projects that could be performed in the future at the ISS-NL—not only for biofuels, but for food crops, medicine, pharmaceuticals, and vaccines.”

Although the researchers are particularly interested in genes that are associated with certain functions, they are not sure what genes will be altered in microgravity. Vendrame says the researchers do not know how microgravity affects gene expression; they have only confirmed through the A. thaliana studies that it does.

But there are several differences between the A. thaliana study and the current one. First, the jatropha experiment is longer than the A. thaliana experiment. The jatropha cell cultures will spend several months in microgravity, while the A. thaliana cultures were in space for only five days. The first set of jatropha cultures were launched with Endeavor in February, and returned to Earth on Discover in April. The second set of cultures were just launched onboard Atlantis in May, and will return in September during the next Endeavor mission.

Another difference is that the jatropha experiments are being carried out onboard the international space station, while the A. thaliana experiment was conducted in the shuttle itself. The jatropha experiment is also studying an increased number of samples, with 72 samples in the first launch, and 86 in the second.

“We know that differential gene expression will occur in our jatropha cells, particularly because they will be exposed to microgravity for four months,” said Vendrame. “We just cannot anticipate which genes will be affected as far as their expression, but we hope to hit a few genes of interest.”

The researchers are currently evaluating the 72 cultures that traveled to space and back in the first round of the experiment. “We are currently performing analyses of cell structure using transmission electron microscopy and hope to start soon the genetic analyses for gene expression,” said Vendrame. “We are also regrowing a portion of the cells exposed to microgravity in the lab and aiming at plant regeneration.” Vendrame hopes that his groups will publish their results within a year, but so far do not have sufficient data or observations to draw any conclusions.

Atlantis launched on May 14th and returned to Earth on May 26th. This mission was Atlantis’ 32nd and final mission before the ship retires this fall along with the rest of NASA’s current shuttle fleet. NASA’s last scheduled space mission will be September’s Endeavor mission, which will bring home the 82 jatropha cultures currently in space.