Learning about biofuels in Brazil
The American Society for Biochemistry and Molecular Biology is playing a vital role in creating the next generation of biofuels. Last fall, the society co-sponsored a week-long advanced course aimed at inspiring interested graduate students and postdoctoral fellows to join the biofuels revolution. At a small resort in the lush coastal city of Ubatuba, Brazil, 40-odd international participants gathered to attend lectures and participate in intense roundtable discussions.
The aim wasn’t to have attendees listen to endless talks, says Bettie Sue Masters, past president of ASBMB and principle organizer of the school. “It was really interactive,” she says. In the daily roundtable sessions, participants had the chance to discuss their own work or research aspirations or to solicit lecturers’ career advice.
Besides being a terrific chance for young researchers to learn about this burgeoning field, it also proved to be a great way to forge a strong partnership between ASBMB and colleagues in the Brazilian Society for Biochemistry and Molecular Biology and the International Union of Biochemistry and Molecular Biology. These groups are planning to cosponsor future meetings, including one in the fall of 2012 on protein folding and protein-protein interactions.
“It was much better than we ever thought it would be – a valuable experience for everyone involved,” Masters says.
However, ethanol also has a number of drawbacks. Crops
used most often to produce it can be finicky about where
they’ll grow. For example, sugarcane, another common
source for ethanol, thrives in Florida but not in Michigan,
and corn needs rich, pampered soil and not rocky, arid land.
Additionally, since the most common sources of ethanol also
are food for people, it sets up a competition over the best
land between food and fuel.
“It could lead to an unstable market,” says Dominique Loque, a research scientist at the Joint BioEnergy Institute in Emeryville, Calif. “Only rich people will be able to drive and eat.”
Consequently, many researchers have suggested gathering
energy from the vegetative tissues of plants instead of the
parts we use for food. Stems, branches, and leaves contain
cellulose, a polymer of glucose in the cell wall that holds
ample energy for conversion to biofuels. Indeed, potential
energy in cellulose is often more than 10 times that available
in starch from a given plant. Moreover, these plant organs are
frequently a throw-away byproduct of the food industry, so
conversion to biofuels could prevent waste.
However, notes Bush, switching from corn kernels to foliage
isn’t so simple. Though researchers have actively worked
on improving corn and other food plants for hundreds of
years, the focus has been on the seed, not the greenery. As
a result, about half of corn’s above-ground biomass is in its
ears. If the new biofuel focus is the rest of the plant, Bush
says, researchers better get cracking on making new energy
crops, such as grasses— significantly bigger.
That’s one of his lab’s projects. With colleagues
at Colorado State University and the
International Rice Research Institute in the
Philippines, Bush is working on identifying
genes that are responsible for making the most
of rice’s green biomass. Rice is a good model for
improving other grasses’ biomass, he says, since
the genomes of all 20 rice varieties have been
sequenced. Bush notes that in this work, rice is
an experimental model and not a target as a biofuel crop.
“A long time ago, many breeders learned that if you see
a very large plant, 50 percent larger than the others, to just
ignore it— they put most of their carbon into vegetative
growth and have lower seed production,” he says. But those
big plants are just what he and his colleagues are looking
for. The researchers have spent many days walking through
rice fields searching for the largest plants produced either
through hybrid crosses or mutagenesis. Using modern deep sequencing
approaches, Bush and his colleagues can then
locate the gene responsible for the plants’ extraordinary size.
The team is now close to identifying the first promising gene
from that approach.
Bush’s lab also is working on another way to make more
greenery through bypassing the feedback system that controls
a plant’s photosynthesis rate. Leaves are the hotbed for
photosynthesis, and as plants spin sunlight into sucrose,
that product is transported to non-photosynthetic tissues
in the plant’s vascular system. If production exceeds export,
Bush explains, plants shut off photosynthesis until the sweet
stuff can distribute to other parts of the plant through its
vascular system. Using sugarbeet as a model system, he and
his colleagues have engineered plants whose cells have a
sucrose transport gene placed behind a constitutively active
promoter. Consequently, the leaves are constantly pumping
out sucrose— and thus, keeping low sucrose in the leaves
and preventing negative feedback on photosynthesis. Over a
season, he hypothesizes, this furious activity translates into
significantly more biomass per plant.