Rice has larger and more complex genome than humans. What does it mean?

Today’s Financial Times (page 5) reports that the “full genetic sequence of rice…has been decoded for the first time…by research teams from Syngenta, the Swiss based biotechnology company, and the Beijing Genomics Institute.” The decoding was published in the journal Science.

Of peculiar interest in the story is that the rice genome may be far more complex than previously thought and that the rice genome contains between 42,000 and 63,000 genes whereas the human genome is estimated to contain between a mere 30,000 to 40,000 genes.

Since we frequently measure how advanced and superior a species by its complexity and, implicitly, by the size of its genome, does this new research indicate that rice is a more advanced, and perhaps even a superior, species than humanity?

Or is it simply the case that superiority is not a matter of complexity nor of the relative size of the species’ genome?

Here is a link to the actual*** Financial Times*** story.

I’m sure the rice think they are superior. :smiley:
Complexity of a species and the size of its genome are not directly corrolative.

Sua

Er, actually, in the category of “things a Financial Times puff piece isn’t going to mention”:

http://botany.sinica.edu.tw/english/menu/project4-n.html

But hey, it sounds really cool for the writer to say, “Yeah, it has way more genes than humans!”

But actually, compared to corn and wheat, it’s dinky. :smiley:
I’m just guessing that all it means is that plants, and flowering plants specifically (angiosperms, which emerged during the Early Cretaceous, 90 to 130 million years ago), and then grasses (which emerged during the Cenozoic–rice is a grass), have been evolving for much, much longer than humans. Organisms tend to keep copies of genes that represent a “been there, done that” stage of evolution, even though they don’t need those genes anymore, and the longer they’ve been evolving, the more copies of “bought the T-shirt” genes they tend to have.

Looking for plant genome sizes on Google…

Corn (maize).
http://www.ncbi.nlm.nih.gov/PMGifs/Genomes/mays_1.html

Wheat.
http://www.nsf.gov/od/lpa/news/press/00/pr0060.htm

Size of genomes:

Rice the smallest of the crop plants.
Corn equals human.
Wheat at least 2 1/2 times size of corn.
Wheat 10 times size of rice.

Looks to me like rice is the least of your worries, Parameter–have you noticed what that box of Wheaties has been up to lately? Pretty quiet out there in the kitchen, eh?

Not to mention the Venezuelan spiny rat (Proechimys trinitatis).

Tables of genome size.
http://www.genomesize.com/mammals.htm

Homo sapiens: 3.50
Venezuelan spiny rat: 6.30

Better watch out.

From a geneticist:

The zebrafish has a genome approximately the size of humans. I work on fruitflies (Drosophila melanogaster), who have a tiny genome (1/3 as many genes as humans, 1/25 the size), and they have a sister species (D. virilis) whose genome is twice as big. Granted, they have something like 30 million years of evolution between them (the distance between humans and mice) but they are not that much more complex, if at all.

Genome size means nothing. Most of the space is repeats. Zebrafish and humans have lots of repeated genes and padding between the genes. Crops have more, not including pseudopolyploidy and true polyploidy that happens pretty often IIRC.

The nature of genomic instability, expansion of repeats, genome size regulation, etc. are very poorly understood at present. There is some correlation with -ploidy (number of copies of a genome) and cell size, and true polyploidy may evolve into a normal diploid with lots of repeats.

As mentioned above, there are only a handful of genes that really count in separating us from mice or from other great apes. The trick is finding out what they are and how they are regulated.

I find the idea that rice is a more complex species than humans to be offensive! :o

Erek

Dogs have way more chromosomes than humans, and presumably a larger genome (though that last bit is a WA assumption). I’ve heard that that’s one reason we’ve been able to breed such a wide variety out of a single species.

What does it mean? It means that plants are WIERD!

Seriously, plant genetics is complex and very interesting. Plant can be polyploid (domesticated wheat is a hexaploid, as I recall) and even aneuploid, while in nearly all animal species polyploidy and aneuploidy are lethal. The size of plant mitochondrial DNA is variable, and often huge, while animals have small mitochondrial genomes which are tightly conserved. And many plants can be mated, not just across species barriers, but across genera; the classic example are orchids, many modern hybrids of which are complex crosses of multiple species in 3 or 4 different genera.

The FT article, which I do not think was a “puff piece” as you suggest, Ms. Goose, is as-of-now research, announced just yesterday as I read the story; where all of your references, Ms. Goose, were last reviewed back in antiquity–and who knows when they were written?

Many thanks, artemis, for a very enlightening reply. Does anyone have any speculations as to why plant mitrochondria would have a much bigger genome than animal mitrochondria? It seems, plants having nothing to do beside stand there, that just the opposite would be the case: that our busy, hard-working muscles would require snazzy, sophisticated power-houses. :slight_smile:

The FT article, which I do not think was a “puff piece” as you suggest, Ms. Goose, is as-of-now research, announced just yesterday as I read the story; where all of your references, Ms. Goose, were last reviewed back in antiquity–and who knows when they were written?

Many thanks, artemis, for a very enlightening reply. Does anyone have any speculations as to why plant mitrochondria would have a much bigger genome than animal mitrochondria? It seems, plants having nothing to do beside stand there, that just the opposite would be the case: that our busy, hard-working muscles would require snazzy, sophisticated power-houses. :slight_smile:

It just means they taste better. This can be seen on the new Rice Chex boxes showing up on store shelves today. “Now, with more Genomes!”

What has allowed the human species to progress and evolve is that we thankfully did not fall into the “tastes like chicken” range of 50 to 53 thousand genomes.

Plants such as broccoli and beets have virtually no genomes, causing the genome sensative area of the tongue to be repulsed, while complex plants such as the cocoa bean, vanilla, and beer plants have an extremely high genome count.

Yes, in fact rice has even developed it’s own religious beliefs, which is why it is now called “converted rice”.

Ugh! That was a groaner, wasn’t it?

It’s all about proteins, folks:

http://news.bbc.co.uk/hi/english/sci/tech/newsid_1910000/1910949.stm

For those uninclined to read, the gist is that the human genome, while it has fewer genes than less-complicated forms of life, has a few more tricks up its sleeve allowing it to build many, many more different kinds of protein. In this story, one scientist says that human DNA can synthesize nearly double the number of proteins compared to rice.

It’s not the size of the genome that counts, it’s how you use it. :smiley:

And here I thought this thread was going to be about Condoleezza Rice. :wink:

If a sizeable fraction of that genome goes toward brain power it means that we are dumber than a grain of rice, which wouldn’t surprise me a bit.

When they get down to the genome of a clod of dirt I’ll start to sweat.

In the first place, why do you consider humans to be superior to other species?

In the second place, rice does not have a larger genome than humans, as the esteemed Duck Duck Goose pointed out. It was, in fact, chosen precisely because it has such a small genome size. There are other organisms which have much larger genomes than humans. There’s absolutely nothing wrong with any of the references that DDG posted. In fact, her citations are closer to the scientists who are actually doing the sequencing work: The National Science Foundation, the National Center for Biotechnology Information (a branch of the National Institutes of Health), and the Academia Sinica.

Maybe we all started out to be rice, but just didn’t make the cut?

(I’ve heard WORSE theologies :smiley: )

No we don’t. At least scientists don’t, as edwino explained. If someone does, it indicates a poor understanding of science. For more information, do a search on the C value paradox.

I tend to agree with the OP. Condoleeza Rice does exhibit skills and talents exceeding many other humans. Maybe it is in the genes…
Oh wait…you are talking about rice grains!!

Listen to edwino. Size doesn’t matter, in terms of genomes.

In fact, I was just reading Stephen Jay Gould’s essay on the subject (“The Ant and the Plant” in Bully For Brontosaurus") last night. He notes that a species of ant, Myrmecia pilosula, was found in the 1980s to actually be several different, though physically similar, species. There are types with nine, ten, 16, 24, 30, 31, and 32 pairs of chromosomes, with concomitantly more and more genetic material. In one of the varieties, the males have but a single chromosome (not even a pair). But they’re all functionally the same type of ant.