Building a better tree
Researchers at UGA have used a gene-editing tool called CRISPR/Cas9 to modify the genome of a tree species for the first time, thereby opening the door to more rapid and reliable gene modifications of plants valued in agriculture and industry.
By mutating specific genes in Populus—a genus of deciduous trees that includes poplar, aspen and cottonwood—the researchers modified the concentrations of two naturally occurring plant polymers: lignin, which traps sugars and starches used for biofuel production inside the tree’s cell walls; and tannin, whose presence in the bark and leaves of the tree deters feeding by ruminants such as deer and cattle.
“CRISPR/Cas9 is a relatively new technology, but it could improve our ability to produce novel varieties of food crops, animal feeds and biofuel feedstocks,” said the study lead researcher C. J. Tsai, a Georgia Research Alliance Eminent Scholar in UGA’s Warnell School of Forestry and Natural Resources and a member of the Department of Genetics. “Compared to some other gene-editing techniques, this one is incredibly simple, cost-effective and efficient. It could serve as the foundation for a new era of discovery in plant genetics.”
CRISPR/Cas9 technology is derived from a defense mechanism of bacteria and other single-celled organisms. When a bacterium is attacked by an invader such as a virus, it captures some of the virus’ DNA, chops it up into pieces and incorporates a segment of the viral DNA into its own genome. As the bacterium experiences more threats, it accumulates a bank of past infections in a special part of its genetic code called CRISPRs, which act as an immune system to protect the bacterium against future invasions.
“Bacteria’s gene-cutting ability is a mechanism that evolved naturally, but we can borrow it to edit very specific genes in all kinds of organisms,” said Tsai. “It’s like using a pair of scissors with GPS tracking to locate and snip out tiny bits of DNA—enough to nullify the gene you don’t want, while leaving everything else unchanged.”
C.J. Tsai is a Georgia Research Alliance Eminent Scholar in UGA’s Warnell School of Forestry and Natural Resources and director of the university’s Plant Center.