French wheat combine
Powdery mildew is a fungal infection that affects the wheat crop. REUTERS

Chinese scientists have used advanced genome-editing techniques to create a strain of wheat resistant to a destructive fungal pathogen called powdery mildew.

To stop the mildew, researchers at the Chinese Academy of Sciences deleted genes that encode proteins that repress defences against the mildew.

At present, wheat is made resistant using heavy fungicides. The new technique allows plant scientists to engineer food crops without inserting foreign genes, as against genetic modification where genes from other species are inserted. In the case of BT crops, a gene from a common soil bacterium is inserted into the crop to make it toxic to insects.

The gene-deletion trick is particularly tough in wheat because the plant has a hexaploid genome, that is, it has six copies of each of its seven chromosomes. Multiple genes must be disabled or the trait will not be changed.

Using gene-editing tools known as TALENs and CRISPR, the researchers were able to do that without changing anything else or adding genes from other organisms. They pointed out that it was no different from a natural mutation.

"We now caught all three copies, and only by knocking out all three copies can we get this mildew-resistant phenotype," said Caixia Gao, who heads a gene-editing research group at the State Key Laboratory of Plant Cell and Chromosome Engineering at the Institute of Genetics and Developmental Biology in Beijing.

Scientists point out to the fact that this knocking out of genes is a non-transgenic technology. The worry is that the government will confuse this with modification. While China has greatly increased investments in basic biotech research, including for genetically modified crops, no new field trials of genetically engineered plants have been approved in more than a year due to public concern over GMOs.

There are currently no commercially planted varieties of genetically modified wheat anywhere in the world.

The fact remains that a single gene is often responsible for more than one trait. In knocking a gene out, the plant may be losing out on some valuable strength. It was recently reported that a group of scientists had urged caution in using this very technology, suggesting that gene drives could end up in rendering some genes more powerful than others, and scientists not wiser on what evolutionary trick has been snipped away.