By Brandon Keim

Future generations of drought-resistant food and biofuel crops may have
their roots in the genome sequence of sorghum, a tropical grass that's able
to thrive in hot, dry conditions.

Having transcribed its DNA, scientists can now set about connecting genes to
hardiness, then applying their insights to the development of crop strains
suited to a 21st century climate.

"It can grow on marginal land. A lot of our own crops can't," said Joachim
Messing, a Rutgers University plant geneticist and co-author of the study
published Wednesday in Nature. "A year ago I was in Mozambique, and the corn
looked terrible, but the sorghum was strong and tall. It doesn't need all
these things that other plants need."

Drought resistance is one of a battery of traits that agronomists hope to
refine in the next several decades, during which Earth's population will
swell by two billion people ? all clamoring for food that modern agriculture
cannot presently deliver.

Developed world farms are already running at maximum capacity, with arable
land already planted and the Green Revolution's fertilizer- and
pesticide-based limits reached. Remaining land is often dry and salty, and
farms around the world are threatened by weather extremes predicted as
consequences of global warming.

New, hardier crop strains are needed ? and perhaps they could be engineered
by applying sorghum's lessons to other plants.

The rigorously deciphered genetic heritage of sorghum and other plants could
help "meet the demands of a world faced by an ever-increasing population and
by an erratic climate," wrote biologists Tajuki Sasaki and Baltazar
Antonioni of Japan's National Institute of Agrobiological Sciences in a
commentary accompanying the study.

"It constitutes the most powerful tool we have for revealing ways to
increase the amounts of food and energy provided by plants," they wrote.

Messing and his colleagues didn't analyze the function of the genes
assembled by sorghum's 750 million base DNA pairs, but they did notice that
sorghum possesses extra copies of a previously-identified family of drought
resistance-related genes.

These genes, he said, could prove central to regulating sorghum's
metabolism.

"The regulation of drought tolerance is very complex, involving many genes,"
said Messing. "Harsh conditions trigger a lot of other metabolic functions
in the plant."

Though sorghum is used primarily for animal feed in the developed world,
these genes could be put into other grass species, from wheat to rice. If
some cultures find genetic engineering to be unpalatable, other plants could
be selectively bred to over-express the genes.

Insights from sorghum could also translate to biofuel development, which has
been hindered by the difficulty of breaking down plant cellulose. One
sorghum strain is high in cellulose, while another is low: by crossing them,
said Messing, scientists could learn how to produce less-woody crops.

Citations: "The Sorghum bicolor genome and the diversification of grasses."
By Andrew H. Paterson, John E. Bowers, Remy Bruggmann, Inna Dubchak, Jane
Grimwood, Heidrun Gundlach, Georg Haberer, Uffe Hellsten, Therese Mitros,
Alexander Poliakov, Jeremy Schmutz, Manuel Spannagl, Haibao Tang, Xiyin
Wang, Thomas Wicker, Arvind K. Bharti, Jarrod Chapman, F. Alex Feltus, Udo
Gowik,
Igor V. Grigoriev, Eric Lyons, Christopher A. Maher, Mihaela Martis, Apurva
Narechania, Robert P. Otillar, Bryan W. Penning, Asaf A. Salamov, Yu Wang,
Lifang Zhang, Nicholas C. Carpita, Michael Freeling, Alan R. Gingle, C.
Thomas Hash, Beat Keller, Patricia Klein, Stephen Kresovich, Maureen C.
McCann, Ray Ming, Daniel G. Peterson, Mehboob-ur-Rahman, Doreen Ware, Peter
Westhoff,
Klaus F. X. Mayer, Joachim Messing and Daniel S. Rokhsar. Nature, Vol. 457
No. 7229, Jan. 28, 2009

"Sorghum in sequence." By Takuji Sasaki and Baltazar A. Antonio. Nature,
Vol. 457 No. 7229, Jan. 28, 2009
www.checkbiotech.org