Loblolly sets record for biggest genome

A giant among trees, the loblolly pine boasts the largest set of genetic blueprints published to date. Even though it’s big on DNA letters, the pine’s instruction book lacks originality: About 82 percent is made of repeating DNA elements.

Researchers first reported deciphering loblolly’s roughly 22 billion letters, or bases, at a conference in 2013 (SN Online: 5/16/13). Now, the team has provided analysis of the loblolly genome in three papers, two in the March issue of GENETICS and one in Genome Biology. Loblolly (Pinus taeda) took the title of largest genome away from wheat, which has 17 billion base pairs.

The conifer can grow to 30 meters tall and is the source of most paper products in the United States. The new results reveal several spots in the pine’s genome that are linked to resistance to pathogens. Continuing to study those regions could help scientists understand how loblollies and other pines battle disease.