Ultima Thule

In ancient times the northernmost region of the habitable world - hence, any distant, unknown or mysterious land.

Tuesday, June 20, 2006

Researchers Offer Clues To How Leaves Patterns Are Formed

By Aussiegirl

A very interesting article on how vein formation in leaves mirrors branch formation on the trunk. My previous post discussed how butterflies hide from rain drops, so perhaps there's a butterfly hiding behind this beautiful leaf.
Researchers Offer Clues To How Leaves Patterns Are Formed

Researchers Offer Clues To How Leaves Patterns Are Formed

Pick up a leaf and it is hard not to notice the pattern made by the veins. For years, biologists, mathematicians and even poets and philosophers have tried to decipher the rules and regulations behind those varied designs and now new research published in part at the University of Alberta offers a big clue to how those patterns are formed.
"For years people have been trying to understand this beautiful formation," said Dr. Enrico Scarpella, from the U of A's Department of Biological Sciences.

"We were able to connect the mechanism responsible for the initiation of the veins in the leaf with that of formation of the shoot and root. With our piece of the puzzle added, it indeed seems the same mechanism is responsible for all these events."

What Scarpella and his research team--Dr. Thomas Berleth's group from the University of Toronto and Dr. Jiri Friml from the University of Tuebingen--discovered has interested scientists around the world. For several years it has been known that a hormone called auxin stimulated the formation of the veins.

"It was believed that auxin would behave like man--build the streets on which man himself would travel," said Scarpella. "However, the theory argued that in each individual vein auxin could only run one way at any given time, making them sort of alternate one-way streets."

By labeling the protein that transports the hormone auxin with a fluorescent tag, he could then shine a light on the leaves and watch how auxin was being transported during vein formation. Thanks to this approach, the team identified cells within individual veins that transport the hormone auxin in two opposite directions. [....]

But one of the biggest discoveries, perhaps the one with the most evolutionary implications, is that plants use the same mechanism to regulate vein formation in the leaf and branch formation on the main trunk and on the main root.

The finding that the leaf is like a two-dimensional model of a tree may change the way plant scientists work, says Scarpella. "If each leaf can make more than 100 veins, you can see the process over and over compared to the formation of branches in a big, three-dimensional slowly growing tree or the difficulties in studying root branching in their natural environment, which is the dirt," he said.

"Our findings will contribute to the way we will manipulate plant development to our advantage. Once we know all the players in the game we will be able to say, we want more leaves on this, more branches on this one or fewer flowers on this plant."


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