The researchers found that the production of a plant hormone called abscisic acid (ABA) increases when plants wilt. They used a method to track the incorporation of a labelled compound called mevalonate into ABA in different plant parts. They discovered that the increase in ABA during wilting is due to new synthesis rather than release from stored forms. The amount of ABA produced varied in different plant tissues and was influenced by the plant's growth conditions and tissue type. Overall, the study shows that wilting triggers the production of ABA in plants, helping them respond to water stress.