The poet Dylan Thomas wrote, "The force that through the green fuse drives the flower drives my green age." Now, a team of international scientists has unlocked some of the secrets of that force: it has described the rules that govern how plants arrange flowers into branching structures, known in technical terms as 'inflorescences.' Nature has literally thousands of examples of inflorescences, which include the flower clusters of Mountain Ash, the tiny filigreed blossoms on Lilac and the stalkier inflorescences in Fireweed.
Published in the May 24 online edition of the journal Science, the team’s paper outlines the mathematical model, molecular genetics and evolutionary processes that work together to create inflorescences as different as Forget-Me-Not and Snapdragon.
"This is a unifying theory that provides an explanation for the diversity of inflorescences we see in nature," says Dr. Przemyslaw Prusinkiewicz, the paper's lead author and a University of Calgary computer scientist. "It was thought that separate mechanisms explained the many differences in form and development of inflorescences in nature, but now we see that these are just facets of the same mechanism."
Dr. Lawrence Harder, a University of Calgary biologist and co-author of the paper, says one of their model's key features is that it is able to anticipate regional variations in inflorescence structures and recognizes that some developmental patterns are impossible.
"What we've done here is to fit together fundamental science from different disciplines to create this exciting new theory," Harder says. "We can now say with more certainty why we have all this diversity that surrounds us; it's also possible that our approach can be adapted to other fields."
A mathematical model that Prusinkiewicz developed has a unique property of producing diverse inflorescence structures with relatively small changes in input, and is a key element of the overall theory. Another is the work of molecular geneticist Dr. Enrico Coen of the United Kingdom's John Innes Centre, who related Prusinkiewicz's model to the action of plant genes.
Other co-authors include Brendan Lane, a University of Calgary computer science research associate, and Yvette Erasmus, a graduate student in the Institute of Molecular Plant Science in Edinburgh.
Reference: "Evolution and Development of Inflorescence Architectures," Science (in press) June 8, 2007.
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