How flowering plants originated about 130 million years ago

May 19th, 2009 - 1:57 pm ICT by ANI  

Washington, May 19 (ANI): A new study is helping shed light on the mystery of the sudden origin of flowering plants about 130 million years ago, with information about what the first flowers looked like and how they evolved from non-flowering plants.

“There was nothing like them before and nothing like them since,” said Andre Chanderbali, lead author of the study and a postdoctoral associate at Unifersity of Florida’s (UF’s) Florida Museum of Natural History.

“The origin of the flower is the key to the origin of the angiosperms (flowering plants),” he added.

The flower is one of the key innovations of evolution, responsible for a massive burst of evolution that has resulted in perhaps as many as 400,000 angiosperm species.

Before flowering plants emerged, the seed-bearing plant world was dominated by gymnosperms, which have cone-like structures instead of flowers and include pine trees, sago palms and ginkgos.

Gymnosperms first appeared in the fossil record about 360 million years ago.

The new study provides insight into how the first flowering plants evolved from pre-existing genetic programs found in gymnosperms and then developed into the diversity of flowering plants we see today.

The study compares the genetic structure of two vastly different flowering plants to see whether differences exist in the set of circuits that create each species’ flower.

Researchers examined the genetic circuitry of Arabidopsis thaliana, a small flowering plant commonly used as a model organism in plant genetics research, and the avocado tree Persea americana, which belongs to an older lineage of so-called basal angiosperms.

“What we found is that the flower of Persea is a genetic fossil, still carrying genetic instructions that would have allowed for the transformation of cones into flowers,” Chanderbali said.

Advanced angiosperms have four organ types: female organs (carpels), male organs (stamens), petals (typically colorful) and sepals (typically green).

Basal angiosperms have three: carpels, stamens and tepals, which are typically petal-like structures.

The researchers expected each type of organ found in Persea’s flowers would have a unique set of genetic instructions. Instead they found significant overlap among the three organ types.

“Although the organs are developing to ultimately become different things, from a genetic developmental perspective, they share much more than you would expect,” Chanderbali said.

According to Virginia Walbot, a biology professor at Stanford University who is familiar with the research, the selection process arrived at a “narrow solution in terms of four discrete organs, but with fantastic diversity of organ numbers, shapes and colors that provide the defining phenotypes of each flowering plant species.” (ANI)

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