Common Sense for the Biochemist

The holy grail of flowering that is. This article gives a good introduction to "Florigen" and its history. I guess I am supposed to be interested in this subject by default as several researchers in the department I work in have been chasing this molecule all of their lives. Florigen is proposed to be a hormone that tells a flower that it is time to make a flower. Classic experiments have shown that florigen is a signalling compound that can be transmitted through a plant. Florigen is produced in leaves in response to being exposed to a certain time period of light. Leaves that are producing florigen can be grafted onto plants that are not flowering and cause them to flower. Furthermore, once this plant has started to flower, leaves from this plant can be grafted onto another plant and cause it to flower, even though both plants have not "seen" the correct amount of light to stimulate natural flowering. The trouble with all of these experiments is that no one has been able to nail down what that signalling compound is and so this mythical florigen compound has become a "holy grail" of some sorts to the plant biology community. However, a group of Swedish researchers have reported in Science that they have identified the gene responsible for the production of florigen. I'll be honest with you though, I have not had time to read the article so I can not comment on it myself. Plant flowering is a big concern in the PMP industry. Of course, transgenic plants that don't flower don't shed pollen that could contaminate the native flora. Added 8/26/05 - After reading the article, the authors imply that an RNA transcript is the actual signal. These transcripts are being produced in the leaf and then transported to the meristem where they are translated into a protein that promotes the expression of flowering genes. Note added in proof: The link to the Science abstract can only be viewed if you have a subscription. I'll try to work on getting another link for this article.