Researchers identify genome sequences of 26 corn strains

Humans adapt through culture and language by transferring knowledge from one generation to the other. Corn plants cannot communicate as such; hence, they address the problem of adaptability in a distinct method—by using “jumping genes” to shuffle the genetic deck over generations.

This ear of corn was grown and analyzed by Nobel Prize-winning Cold Spring Harbor Laboratory (CSHL) geneticist Barbara McClintock decades ago. From her observations, she surmised that parts of the corn genome jumped from one location to another, generating a great deal of genetic diversity—in this case many different colors of kernels. CSHL researchers expanded on her work by sequencing the genomes of multiple corn strains, mapping even the mobile portions of the genome. Image Credit: Cold Spring Harbor Laboratory Library & Archives.

Jumping genes—now known as transposons—were identified by Nobel Prize-winning Cold Spring Harbor Laboratory (CSHL) geneticist Barbara McClintock during the 1940s. Years later, CSHL researchers are still expanding on her work.

Doreen Ware, CSHL adjunct professor and research scientist at the US Department of Agriculture (USDA), and her co-workers published genome sequences from 26 different strains of corn in the Science journal. The genomes detail a huge portion of the genetic diversity identified in modern corn plants, including transposons and genes that regulate desired crop traits.

Corn grows in different climates of the world, from highlands to lowlands and from temperate to tropical.

Humans have brains. Our main adaptive component is our ability to transfer culture and knowledge, right? And that’s how we deal with our environment. A plant’s strategy is to have a fluid genome.”

Doreen Ware, Adjunct Professor, Cold Spring Harbor Laboratory

“They have a very intimate relationship with these transposons, where they use them to bring in new genetic diversity so that they can deal with these events because they can’t run away. They’re not going to go into the house, and they’re not going to move water to them,” added Ware.

Ware and co-workers, including CSHL Professor and HHMI Investigator Rob Martienssen and CSHL Professor W. Richard McCombie, mapped the first corn genome in 2009, and they have been filling in gaps since then. Similar to a continental landscape, genomic maps have areas that are full of traits (such as well-mapped cities); on the other hand, others are more like deserts (vast and uncharted).

Employing state-of-the-art techniques, the researchers mapped difficult stretches of the genome, even the deserts. These complete genomes enable scientists to locate and examine both important crop genes and the adjacent regions that regulate their use. Ware remarks, “we had little access to the regulatory architecture of corn before.”

The current collection shows how the corn genome was shuffled over time.

These genomes provide us a footprint of that life history. Different strains have experienced different environments. For example, some came from tropical environments, others experienced particular diseases, and all those selective pressures leave a footprint of that history.”

Doreen Ware, Adjunct Professor, Cold Spring Harbor Laboratory

Corn is one of the most common agricultural staples in the world, with around 366 million metric tons grown in the United States from 2018 to 2019. The elaborate maps of the corn genome can enable researchers to move forward in creating crops for a rapidly changing climate.

The Midwest is not going to have the same temperature profile twenty years from now. The genomes provide broader insights into corn genetics, and this, in turn, can be used to start optimizing corn to grow in future environments.”

Doreen Ware, Adjunct Professor, Cold Spring Harbor Laboratory