"Efficiency of editing can be a problem in some crop species," Van Eck says. As opposed to diploid plants like tomato (which have paired chromosomes), those that have more than two paired sets of chromosomes (known as polyploid, like wheat), are much harder to work on. "You basically have more copies of a gene in polyploids that need to be affected by Crispr than in a diploid," Van Eck adds.