You Say Genome Editing, I Say Natural Mutation
Published:10 Jan.2024 Source:Cold Spring Harbor Laboratory
Today, CRISPR genome editing allows us to make new crop mutations that improve traits even further. However, individual mutations, whether natural or engineered, don't work alone. Now, a plant geneticist and a computational scientist at Cold Spring Harbor Laboratory (CSHL) have teamed up to explore just how predictable plant breeding actually is with natural and CRISPR mutations. To do so, they turned back the evolutionary clock. CSHL Professor & HHMI Investigator Zachary Lippman and Associate Professor David McCandlish wondered if different natural and engineered mutations could have similar effects on tomato size depending on the presence of two other gene mutations.
Using CRISPR, they created a series of mutations in the SlCLV3 gene. (Natural mutation of this gene is known to increase fruit size.) They then combined those mutations with others in genes that work with SlCLV3. Altogether, they created 46 tomato strains with different combinations of mutations. They found the SlCLV3 mutations produced more predictable effects when certain other mutations were also present. Mutations in one gene produced predictable changes in tomato size, but mutations in another yielded random outcomes. Remarkably, the most beneficial effect involved two mutations that arose millennia ago and were central in tomato domestication.
New research by McCandlish and Lippman may help us better understand genetic predictability. But one thing's certain. Context matters when introducing new crop mutations. Lippman and McCandlish's work suggests the role of background mutations demands reassessment. "The field will have to grapple with this as we start to make more highly engineered organisms," says McCandlish. "Once you start making 10, 20 mutations, the probability of having unanticipated results may increase."