Archive for dezembro 20th, 2013

Evolução das Plantas: Amborella e Darwin’s abominável mistério

sexta-feira, dezembro 20th, 2013

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

Oldest Flowering PlantScientists 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. (Photo : Penn State University)

Dictionary: thrived or throve (thr v), thrived or thriv·en (thr v n), thriv·ing, thrives. 1. To make steady progress; prosper. 2. To grow vigorously; flourish


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.

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 evidence that the ancestor of all flowering plants, including Amborella, evolved following a “genome doubling event” which occurred about 200 million years ago. While some duplicated genes were lost over time, others took on new functions, including contributions to the development of floral organs.

“Genome doubling may, therefore, offer an explanation to Darwin’s ‘abominable mystery’ – t he 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.”


–  “genome doubling event”

 Wikipedia:  Paleopolyploidy is the result of genome duplications which occurred at least several million years ago (MYA). Such an event could either double the genome of a single species (autopolyploidy) or combine those of two species (allopolyploidy). Because of functional redundancy, genes are rapidly silenced and/or lost from the duplicated genomes. Most paleopolyploids, through evolutionary time, have lost their polyploid status through a process called diploidization, and are currently considered diploids (e.g. baker’s yeast,[1] Arabidopsis thaliana,[2] and perhaps humans[3]).

Paleopolyploidy is extensively studied in plant lineages. It has been found that almost all flowering plants have undergone at least one round of genome duplication at some point during their evolutionary history. Ancient genome duplications are also found in the early ancestor of vertebrates (which includes the human lineage) and another near the origin of the bony fishes. Evidence suggests that baker’s yeast (Saccharomyces cerevisiae), which has a compact genome, experienced polyploidization during its evolutionary history.

(Continuar a ler…)

Wikipedia:  Gene duplication (or chromosomal duplication or gene amplification) is a major mechanism through which new genetic material is generated during molecular evolution. It can be defined as any duplication of a region of DNA that contains agene. Gene duplications can arise as products of several types of errors in DNA replication and repair machinery as well as through fortuitous capture by selfish genetic elements. Common sources of gene duplications include ectopic homologous recombinationretrotransposition event, aneuploidypolyploidy, and replication slippage

( continuar a ler…)

Ver google search for genome doubling event


– Procurar na formula da Matrix/DNA, a explicação para isto: 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.

– eudicot