Scientists for the first time used a gene editing tool known as CRISPR/Cas to modify the genome of a tree species. Researchers at the University of Georgia have completes this inovative experiment, which opens the door to more rapid and reliable gene editing of plants, by editing genes of species of Populus. This new gene editing tool can help scientists to improve producing of food crops, animal feeds and biofuel feedstocks.
Populus is a genus of deciduous trees that includes poplar, aspen and cottonwood. Now researchers, using genetic engineering, managed to reduce the concentrations of two naturally occurring plant polymers. One such polyer, called lignin, traps sugars and starches used for biofuel production inside the tree’s sturdy cell walls. Another, known as condensed tannin, which is concentrated in leaves and barks of the tree. It deters feeding by ruminants, such as deer, cattle, goats and sheep.
CRISPR gene editing tool is developed using defense mechanism evolved in bacteria and other single-celled organisms. Under attack of invader, for example, a virus, bacteria captures some of the virus’s DNA and incorporates pieces of it into its own genome. During number of such attacks bacteria accumulates a bank of past infections in a special part of its genetic code called CRISPRs (short for clustered regularly interspaced short palindromic repeats) and it later act as immune system to protect bacteria against future invasions.
Poplar plants produced by scientists using CRISPR gene editing tool had red wood, which is a sign that a lignin-gene-targeting experiment was successful. Image courtesy of news.uga.edu.
CRISPR, as a gene editing tool, is fairly new and it has been tested for the first time. However, it is a great improvement over past gene editing techniques. Chung-Jui Tsai, lead researcher of the study, said that “compared to some other gene editing techniques, this is incredibly simple, cost-effective and highly efficient, and it could serve as the foundation for a new era of discovery in plant genetics.” It is also a great example of how scientists seek for inspiration in nature.
This defence mechanism in bacteria evolved naturally and now scientists can borrow the bacteria’s gene-cutting abilities and use it to edit very specific genes in all kinds of organisms, including plants and animals. It can be used in a very precise way – CRISPR gene editing technique can nullify undesired gene, while leaving everything else unchanged. It is very useful for variety of gene engineering projects, from improving food crops to creating better biofuel plants.
Every single poplar that scientists produced using this method had red-colored wood. Red colour of the stem is a known side effect of lignin modification found in natural mutants of maize, sorghum and pine. Fact that every single sample had red colour signifies how efficient new method is. In fact, it surprised scientists themselves, as experiments demonstrated far greater efficiency than animal models where the technology has been more extensively tested.
Populus plants with modified genes using CRISPR gene editing technique contained about 20 percent less lignin and 50 percent less condensed tannins than wild trees, which are extremely good results. However, scinetists found out something new as well. They were expecting even greater efficiency as they thought that they know what genes control lignin and condensed tannin production and targeted these genes. But now they found out there are other genes with overlapping roles. New CRISPR technique borrowed from the nature can help scientists to explore new possibilities of genetic engineering and provide better understanding of roles of specific genes.