Re: Is there more DNA in plants or mammals?

This question is a bit tricky to answer, but here’s what I found:
The numbers below were found through the Database Of Genome Sizes web site 
at: http://www.cbs.dtu.dk/databases/DOGS/

Plants show an enormous range of genome sizes.  Arabidopsis thaliana, a small 
mustard plant, has the smallest known plant genome.  It is about 125 million base 
pairs.  However, some kinds of lily have a genome of about 125 BILLION base 
pairs, which is a thousand times larger than that of Arabidopsis.  This range makes 
it difficult to generalize the size of plant genomes.

The range for mammals is much smaller.  The smallest known mammalian 
genome, at 1.7 billion base pairs, belongs to the bent wing bat.  The largest known 
mammalian genome, found in echymid rodents, is about 6.3 billion base pairs, 
which is less than 4 times the size of the bent wing bat genome.  The human 
genome is around 3 billion base pairs, and the mean value for all known 
mammalian genomes is 3.5 billion base pairs.

Let’s look at a smattering of plants:

Rice 430 million
Maize (corn) 2.5 billion
Wheat 16 billion
Lily 125 billion
Oak trees 883 million
Maple trees 1.2 billion
Lettuces 2.4 billion
Soybean 1.13 billion
Alfalfa 1.75 billion
Orange 630 million
Apple 2.25 billion
Dandelion 1.28 billion
Pines: 23.64 billion
Giant sequoia: 9.9 billion
Coast Redwood: 32 billion
Fir tree 15 billion
Cycad 13.75 billion
Adiantum fern: 4.65 billion
Tree fern: 7.35 billion
Physcomitrella moss 511 million
Aulacomnium mosses 340 million

Based on this small sample size, it looks like the genomes of ferns and cone 
bearing trees are generally larger than mammalian genomes, while moss genomes 
are smaller.  Flowering plants are really all over the place, with the smallest 
(Arabidopsis) being  only about 3.5% the size of the average mammalian genome, 
but many of them being several times larger than mammalian genomes.
So you can see, it’s difficult to give a simple answer to your question.  If I had to 
make an estimate, I would guess that, since many plant genomes are really large, 
that if you calculated the average size of all plant genomes, it would be larger than 
3.5 billion base pairs.

Alex Brands
Lehigh University