Sugarcane is a staple food crop with plenty of room for improvement because of its substantial environmental burden. However, it’s time-consuming and complicated to breed new varieties. Hence, researchers decided to try using CRISPR gene-editing to do the task more quickly and easily. And it worked!
Sugar isn’t the only product that sugarcane provides. The crop is also a source of oil and bioethanol used to make greener plastics and fuels. Sugarcane supplies 80% of the sugar and 30% of the bioethanol produced worldwide, making it one of the most productive plants on Earth.
All this demand means the crop takes up a vast percentage of farmland in several countries, which unfortunately fuels deforestation. It also requires a lot of water to grow and generates lots of pollution and waste during processing.
New varieties of the plant could address some of these issues. But sugarcane is difficult to crossbreed because of its highly complex genome, requiring over a decade of trial and error to develop an improved cultivar. It has multiple sets of chromosomes (rather than just two like usual) because it’s a hybrid of two kinds of parent plants.
Fortunately, the precise gene-editing technology CRISPR-Cas9 offers a much more targeted path to crop improvement as it simply changes inferior gene versions into superior ones rather than laboriously reshuffling genetic information. CRISPR/Cas9 allows scientists to switch off genes or cut them out entirely and replace them with more useful ones.
CRISPR/Cas9 is known for its usefulness in medicine, but not so much so in crop modification – and this is the first time it has been successfully used on sugarcane.
Fredy Altpeter, the lead researcher on both studies, said:
Now we have very effective tools to modify sugarcane into a crop with higher productivity or improved sustainability. It’s important since sugarcane is the ideal crop to fuel the emerging bioeconomy.
University of Florida researchers conducted two separate studies to demonstrate the first successful precision breeding of sugarcane using CRISPR/Cas9 genome editing. The results reveal the method is a far more targeted and efficient way to develop new varieties.
The team focused on a few genes that control noticeable traits so the changes would be apparent. They went with leaf color for the first study and herbicide resistance for the second.
To target leaf color, the researchers turned off several copies of a gene that produces magnesium chelatase – an enzyme for chlorophyll biosynthesis in sugarcane. This modification made plants with light green to yellow leaves instead of the typical darker green. Furthermore, they didn’t show signs of growth reduction and appeared to require less nitrogen fertilizer to produce an equal biomass amount to unmodified plants.
To improve the sugarcane’s resistance to herbicides, the researchers replaced individual nucleotides – chemicals that can inhibit particular genes in the plant – with better versions. The edit made them more resilient so that less herbicide would be needed.
The results of these two studies could lead to breakthroughs in sugarcane farming, opening up a more effective method to breed better varieties that address the plant’s numerous environmental concerns.
