PROCERA is a gene involved in growth regulation in tomato. Destructing the proteins made from this gene induces growth. In a previous study, this gene was edited to lose its function in tomato so that the plant will be dwarfed. To verify if this gene is responsible for the dwarf trait, the mutated version of the gene is modified back to its original. If the original trait is obtained, the targeted gene can be concluded to be responsible for the trait of interest.

Researcher Neil Olszewski from University of Minnesota and colleagues modified the PROCERA gene using TALENs and obtained tall plants. Then, these plants were applied with CRISPR-Cas9, and the dwarf trait was obtained. Thus, this gene can be said to be responsible for the height difference in the plants with mutation generated using TALENs and the plants with mutation generated using CRISPR-Cas9. 

For more information, read the article in Plant Biotechnology Journal.