biology evolution Genetics Plants research stories

The Newly Published Soybean Genome and Fractionation

Here’s the key statistic: The maize genome paper estimated that roughly a quarter of maize genes are currently retained as duplicate pairs from maize’s whole genome duplication, while the soybean paper estimates just over half of soybean genes are similarly retained after soybean’s (apparently slightly older) duplication. <– had it buried at the end of this, but figured it’d be more fun to start out with something cool.

But first of all, let’s do this the right way this time. Here’s the paper in Nature describing the soybean genome. Here’s one of the places you can download the entire sequence from. Hopefully that establishes, beyond a reasonable doubt, that the soybean genome has, in fact, been published.

biology Genetics Plants

Maize: The Genome Sequence Itself

The corn genome is ~2.4 gigabases (2.4 billion As, Ts, Cs, and Gs) divided among ten chromosomes. The genome of sorghum, the most closely related species with a sequences genome to maize, is also divided into ten chromosomes, but it’s only less than 800 megabases long, approximately a third the size of maize.

What accounts for the size different? Well since their divergence, maize went through a whole genome duplication, doubling it’s genome to twenty chromosomes (which have since been reduced to ten again, as pieces of chromosomes broke apart and stuck to each other*). Since then a bunch of deletions have also occurred, so only sometimes like 20-30% of the genes from the ancestor of maize and sorghum can still be found in both duplicated regions. Clearly the genome duplication of maize is not responsibly (or at least not solely responsible) for the the enormous size of the maize genome.