The codes for our lives are contained in the large genomes of humans. Do you want to explain your dark hair and dreads? Take a look at your chromosomes and base pairs.
There are more base pairs and more chromosomes in the genomes of two different organisms. I wonder if it is an animal? Is that an animal? An animal? The tree is a spider monkey tree.
The flying spider monkey tree fern, a hardy plant found in Southeast Asia, has flat leaves that fan out in a circle at the top of its trunk. The biggest question in the field of genetics is what accounts for so much genetic material.
In May, Dr. Li led a team that was trying to get an answer to a question. It was the first time that a fern had a genome so large that it was mapped and the third time that a fern had its genes mapped. Two more papers were published last week in Nature Plants, revealing that the maidenhair fern and the "C-Fern" had genomes comparable to the flying spider monkey tree fern.
A half century old hypothesis about fern genes has been challenged by this burst of research. It doesn't close the case of the fern genome, but it might give us a better idea of genome evolution as a whole.
Eric Schuettpelz, who was not involved in the recent research, said that it had been decades since they had begged for it. These are great times.
Plants and animals with lots of genes aren't necessarily physically or behaviorally more complex. The current record for most base pairs is 149 billion, and the record for most chromosomes is 1,440. Both plants are easy to grow.
Polyploidy is a common explanation for large genomes. Two gametes, cells with half the number of chromosomes, come together to create a zygote, with a full suite of genes. When these gametes first form, it is possible that pairs of chromosomes do not fully separate, leading to a zygote with a genome that is twice the size of its parents. Most of the duplicated genes have been removed after tens of millions of years of natural selection.
Ferns have more base pairs in their genomes than flowering plants. Scientists have been wondering why this was so for a long time. In 1966 a paper was published in Science that claimed that the fern gained an advantage from genome duplication. The authors said that the extra genes helped prevent hereditary diseases.
Pamela Soltis is a botanist at the Florida Museum of Natural History who helped sequence the C-Fern. Is it possible that fern genomes contain signs of mass duplication? The theory needed some of the large genomes to be confirmed.
The sequence did not show evidence of polyploidy. Dr. Soltis said that none of that happened. There is only evidence for possibly two duplications in this whole lineage that have been around for hundreds of millions of years.
The C-Fern appears to have gained its large genome from repetitive DNA and transposable elements, with a function that is difficult to understand. The conclusion of the longstanding hypothesis of polyploidy was offered by the sequence. She said that this was the nail in the coffin.
Dr. Li wasn't so sure. Around 100 million years ago, the genome of the flying spider monkey tree was duplicated, but it has remained stable. It seems to support the idea that polyploidy gave the plant an evolutionary leg up. He said that one of the genomes supports the hypothesis.
"We don't have a firm grasp on what these things are doing, but I've just been amazed." Things are going to get really exciting as we accumulate more and more genomes.
The fern scientists all agreed on this. Dr. Marchant said that the publication of more and more genome assembly to compare will make inferences more useful.
In order to understand aspects of flowering plants, we need to compare them in their evolutionary context. There was no reference until the fern genomes were published.
Dr. Soltis is involved in a project to sequence the genomes of all life on the planet. She acknowledged that the project isambitious but also science. She said, "To understand how anything works in any organisms, including ourselves, you need to look at where it came from and what its context was before taking on whatever function it has now."
Dr. Li asked what we needed. We need more genetic material.
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