Scientists have used pollen carrying CRISPR/Cas9 to genetically edit hard-to-edit crops like corn, opening the door to new ways to boost important crop yields.
CRISPR/Cas9 Used on Edit-Resistant Corn Crops
Scientists at the North Carolina-based agricultural firm Syngenta have discovered a novel way to use CRISP/cas9 gene-editing techniques on important varieties of corn that have proven especially resistant to the process, according to Science magazine.
The researchers used the pollen from a genetically-edited plant as a means of delivering the desired genetic edits into the cells of another plant. They describe their technique in a paper published today in the journal Nature Biotechnology.
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For some varieties of plant species, gene-editing can be difficult because the cell walls of the plant are too thick for the mechanism that edits the cell’s genome to actually get to where it needs to go. Animal cells don’t have the stiff cell walls that plant cells do so it has been much easier to use CRISPR/Cas9 and animal cells to great effect. Other plants cell walls aren't as stiff as others and are able to be edited.
Scientists have been trying to find better, more efficient ways to gene-edit important staple crops like corn and wheat than the current methods they have available. Their hope is to use the technique to produce heartier plants which will increase crop yields.
CRISPR Carrying Pollen Provides A Solution
The researchers, plant biologist Timothy Kelliher and Quideng Que, used a novel approach to solving this problem of penetrating the stiff cell walls of corn. They utilized something known as haploid induction to carry the CRISPR/Cas9 edits into the plant cells that had proven so stubborn.
Haploid induction is an unusual occurrence when pollen is able to fertilize plants, but not permanently transfer the “male” plant’s genes to its offspring. This results in plants that only have the “female” chromosomes of the pollinated plant, making them haploid rather than diploid, as is normally the case.
The researchers took a corn variety that is much easier to edit with CRISPR/Cas9 and edited plants that had a deformed version of the gene MATRILINEAL. This gene makes the plant produce pollen that triggers haploid induction.
By editing this plant with CRISPR/Cas9 edits that targeted desired traits in the more resistant corn varieties, the researchers were able to have the pollen of the edited plant spread the desired edits to the CRISPR/Cas9 resistant plants it pollinated.
“The key innovation is using haploid inducer pollen as a sort of Trojan Horse,” Kelliher says.
While this technique has only been done in a lab so far, if it were performed on crops in an actual field, there isn’t any concern that these edits would permanently alter the edited corn.
Since it is only the pollen that carries the CRISPR/Cas9. Since these changes aren’t spread to the offspring or DNA, only the pollinated plant is affected, the gene-editing apparatus disappears after fertilization, at which point the pollinated plant as received the desired edits.
“It is a brilliant piece of work,” says Luca Comai of the University of California, Davis, whose lab has received funding from Syngenta in the past but was not part of this research. “It is imaginative by combining two technologies: haploid induction and genome editing.”