Knocking out genes is a great way to learn what they do. After all, if you prevent a gene from doing its job and you notice changes, it’s very likely the gene has something to do with it. There is a caveat, though. Mutations in genes that are required for basic cellular functions and/or reproduction often interfere with the generation of homozygous mutant plants, precluding further functional studies. Additionally, some genes have different functions in different parts of a plant, so the effect of a gene in one part could mask the effect elsewhere.