DNA Of Oldest Flowering Plant 'Solves' Darwin's 'Abominable Mystery'-Scientists Say

Dec 20, 2013 01:34 PM EST


Scientists have newly sequenced the genome of the Amborella plant, one of the two oldest lineages of flowering plants, for the first time, potentially addressing Charles Darwin's "abominable mystery" - the question why flowers suddenly thrived on Earth millions of years ago.

Found on the main island of New Caledonia in the South Pacific, the Amborella plant (Amborella trichopoda) is a small tree with white-ish yellow flowers.

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It is considered to be the unique sole survivor of an ancient evolutionary lineage that traces back to the last common ancestor of all flowering plants. An understory tree is one that grows beneath a forest canopy without rising above it.

Scientists at Penn State University, the University at Buffalo, the University of Florida, the University of Georgia, and the University of California-Riverside sequenced the plant's genome and published a full description of the analysis in the journal Science.

The genome sequencing of Amborella is expected to provide evidence for the evolutionary processes that paved the way for more than 300,000 flowering plant species that are found on Earth today.

"In the same way that the genome sequence of the platypus - a survivor of an ancient lineage - can help us study the evolution of all mammals, the genome sequence of Amborella can help us learn about the evolution of all flowers," Victor Albert of the University at Buffalo said in a statement.

The plant's DNA provides conclusive evidence that the ancestor of all flowering plants evolved following a "genome doubling event," which happened about 200 million years ago. During this time, some duplicated genes were lost but others look on new functions, including contributions to the development of floral organs.

"Genome doubling may, therefore, offer an explanation to Darwin's 'abominable mystery' - the apparently abrupt proliferation of new species of flowering plants in fossil records dating to the Cretaceous period," Claude dePamphilis of Penn State University said in the statement.

The researchers believe that Amborella's genome will provide new insights on important traits in all flowering plants, including among all major food crop species, meaning farming could be improved.

That is, they can now study the genetic history of all flowering plants, and know how genome duplication may have played a role in the evolution of traits like drought-resistance or fruit maturation.

This work provides the first global insight as to how flowering plants are genetically different from all other plants on Earth," said Brad Barbazuk, from the University of Florida said. "It provides new clues as to how seed plants are genetically different from non-seed plants."

As the oldest surviving branch of flowering plants, the Amborella genome allowed researchers to estimate the linear order of genes in an ancestral plant genome called "eudicot," and to infer lineage-specific changes that occurred over 120 million years of evolution in the core eudicot.

The research in question is among three different studies related to the Amborella genome.

One of the other two reports is about the complete mitochondrial genome sequence of Amborella, which contains large amounts of foreign DNA resulting from horizontal gene transfer. The third report describes a new tool used to sequence and assemble the Amborella genome that can be implemented to most plants and animals with large, complex genomes.

"Sequencing the genomes of individual Amborella plants across the species' range reveals geographic structure with conservation implications and evidence of a recent genetic bottleneck," Pam Soltis of the University of Florida said in a statement.

"A similar narrowing of genetic variation occurred when humans migrated from Africa to found modern-day Eurasian populations."




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