Plants ability to produce flowers at the same time year-in-year-out has fascinated botanists and scientists alike for many years. The processes by which this is achieved are still not completely understood, though advances in technology are producing some exciting discoveries.
The three main pathways that have so far been discovered to be involved in the flowering process are; the photoperiod pathway (light intensity and day length), vernalization (temperature sensitive), and autonomous pathway (not affected by environmental conditions). Both the photoperiod pathway and vernalisation are examples of non-autonomous pathways and use environmental cues to regulate flowering time.
The photoperiod pathway is able to stimulate flowering by detecting increasing day length and inducing the expression of a flowering locus. In Arabidopsis it is believed that increased day length, detected by the photoreceptors, stimulate the activation of signalling proteins. Higher levels of these proteins have been found in Arabidopsis in longer days compared to short, which in turn up regulates the expression of a flowering locus and induces flowering.
Work carried out by Yavonsky and Kay, have shown that Arabidopsis with mutant circadian genes are still able to regulate flowering time when exposed to longer ‘day’ length, indicating that flowering can be controlled even if internal mechanisms are faulty.
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Toby Mitchell (41450550)
References
Yanovsky, M. J. & Kay, S. A. (2002) – ‘Molecular basis of seasonal time measurement in Arabidopsis’, Nature, 419:308-312
Amasino, R. M. (2003) – ‘Flowering Time: A Pathway that Begins at the 3’ End’, Current Biology, 13:670-672
