Changing a flower's color with the CRISPR gene-editing tool
It often takes years of careful cross-breeding for horticulturalists to turn flowers certain colors, but scientists can dig right in and change them at a genetic level much faster. Using the CRISPR-Cas9 gene-editing tool, scientists have changed the flowers of the Japanese morning glory from its usual violet color to a pure white, by disrupting a single gene.
CRISPR-Cas9 is a genetic tool that allows scientists to make precisely targeted edits to an organism's DNA, and over the years it's been used to tackle cancer and other illnesses, fight superbugs and improve crops. Now a Japanese team, made up of scientists from the University of Tsukuba, Yokohama City University and the National Agriculture and Food Research Organization (NARO), has turned the technique towards ornamental plants.
The flowers of Ipomoea nil, or the Japanese morning glory, normally come in shades of purple, pink and rose, with some varieties outlined or splotched with white. The plant's genome has been fully sequenced, and it's available for scientific study in the Japanese National BioResource Project (NBRP), making it the perfect candidate for the research.
The team focused their work on a single gene called DFR-B, which encodes for an enzyme that gives the flowers and stem of the plant its color. By snipping that gene out of the morning glory's DNA, the researchers hypothesized that the flower should become colorless. But the real test of CRISPR's accuracy would be to deactivate DFR-B without disrupting other closely-related genes, DFR-A and DFR-C.
Hitching a ride on a bacterium called Rhizobium, which can transfer DNA, CRISPR was injected into cultured embryos of the plants. Sure enough, about 75 percent of the plants that grew out of the process sprouted pure white flowers and green stems, as opposed to a control group with the usual violet flowers and stems.
It may seem like a fairly cosmetic change to make, but the experiment has several wider implications. Since neither DFR-A or DFR-C was affected by the procedure, it shows how precise the CRISPR technique can be, and the function of specific genes can be confirmed by observing the effects of tweaking them. This particular case confirms that DFR-B is responsible for the plant's color.
The experiment raised an interesting dilemma as debate rages about the ethics and regulation of genetic modification. The next generation of the modified flowers were also white like their parents, but some of them showed no signs of the DNA introduced by the CRISPR-Cas9 system. That seems to blur the line between whether or not these plants should be considered transgenic: a process-based definition would conclude that they are, since they were "made" through gene-editing techniques. But according to a product-based definition, which is judged by foreign DNA in the organism's genome, they're non-transgenic.
The research was published in the journal Scientific Reports.
Source: University of Tsukuba