Largest Genome Sequenced: Loblolly Pine's Genetic Code Is 7 Times Larger Than A Human’s

A team of researchers have sequenced the genome of the Pinus taeda, commonly known as the loblolly pine, and found that the tree’s genetic code -- seven times larger than a human’s -- is the largest and the most complete conifer genome ever sequenced.

According to the study, the sequencing of the loblolly pine's genome was completed by using a faster and more efficient analytical process, including advanced computer technology. The genome sequence of the tree, which is the most commercially important tree species in the U.S., is expected to help scientists breed improved varieties of the pine and better understand the evolution and diversity of plants.

“It’s a huge genome,” David Neale of the University of California, Davis, who led the research, said in a statement. “But the challenge isn’t just collecting all the sequence data. The problem is assembling that sequence into order.”

The loblolly pine is one of several pines native to the southeastern U.S., spreading eastward from central Texas to Florida, and northward to Delaware and southern New Jersey. The tree is milled for building lumber and paper, while it is also the primary source of pulpwood and saw timber for the country's forest products industry.

To tackle the enormous size of the loblolly pine genome, which has 22 billion base pairs compared to only 3 billion in the human genome, scientists used a new method that could speed up genome assembly by compressing the raw sequence data 100-fold, according to the study, which has been published in two papers in the March 2014 issue of Genetics, and in one paper in the open access journal, Genome Biology.

As part of the study, scientists also looked for genes that control resistance to fusiform rust, a disease that infects southern pines and renders them unfit for use. According to scientists, they found a whole family of resistant genes in the loblolly pine’s genome.

“Commercially, it is the most economically devastating disease of the southern pines,” John M. Davis of the University of Florida, said in a statement. “If growers didn’t have genetic resistance, we would have no pine plantations – it’s that important.”

Florida’s nearly 16 million acres of timberland supported economic activities that generated $14.7 billion in economic impact in recent years while providing nearly 90,000 full- and part-time jobs. A molecular understanding of genetic resistance is a valuable tool for forest managers as it allows them to select trees that can develop into healthy groves.