Genetics professor Zachary Lippman, together with team, shared the result of
their study on cryptic mutation and some vital lessons for gene editing in
crops. Their study is published in Nature Plants.

The research is founded in the story of Campbell Soup Company and a field of
tomatoes back in the mid-20th century. In the field of tomatoes, one plant
had a surprising characteristic-the fruits separated from the vine right
where the green cap and step touch the rest of the fruit. This jointless
mutant plant was ideal for large-scale production because the other
varieties would break away at a joint-like nub in the fruit stem, leaving
pointed green caps that puncture other tomatoes in transit. The breeders
called the gene mutation as jointless-2 (j2) and tried to introduce it into
many varieties. However, doing so led to jointless tomato plants with
excessive branching.

In 2017, Lippman and colleagues revealed that an ancient gene mutation
interferes with j2 leading to a cryptic mutation. Now with the advent of
gene editing techniques such as CRISPR, scientists can make fine adjustments
in the mutations to prevent negative interactions that hinder agricultural
production. Lippman also found that some breeders were able to neutralize
negative interactions by duplicating the ancient mutation that interacts
with j2. In other words, doubling the ancient mutation gives the same result
as having no mutation at all.

"This [duplication event] was naturally occurring, so basically, nature
provided the solution to its own problem," Lippman stressed.

[www.cshl.edu]
ng/