Few acts of nature seem simpler than flowers blooming on the outstretched tips of a plant’s shoots. But the induction of that seemingly simple process baffled plant biologists for almost 60 years.
In the 1930s, Cornell University plant scientist James Knott coined the term “florigen” for a mysterious signal that instructs flowers to begin growing at the tips of stems, called apical meristems.1 Researchers knew and had demonstrated that changes in day length and temperature caused plants to flower, a process essential to plant reproduction. Knott tracked the unidentified florigen traveling through the vascular system of a spinach plant, and other scientists worked out parts of the molecular pathway that allowed plants to sense environmental changes and respond by producing flowers. But the chemical identity of florigen eluded discovery. “It was a technical challenge to put that last nail in the coffin,” says Richard Amasino, a plant scientist at the ...
