DNA doubled in conifer ancestors

Douglas fir trees in Bryce Canyon

Ancestors of  Douglas firs (Pseudotsuga menziesii), such as this one growing in Bryce Canyon National Park, and other conifers underwent genome duplication — adding extra copies of genetic material — around the time of the Permian-Triassic extinction.

Zheng Li

Conifers grew giant genomes thanks to double doses of genetic material. Ancient ancestors of today’s pine, cypress and yew trees had extra copies of their entire genome, the set of genetic instructions for an organism, researchers report November 20 in Science Advances.

Whole genome duplications are common in plants, but a previous look at Norway spruce DNA found no evidence of such doubling (SN Online: 5/22/13). The new study examined the entire set of active genes, or the transcriptome, of 24 conifers and other seed plants and three distantly related plants.

In ancestors of cypress and yew trees, genome duplication occurred about 275 million to 210 million years ago, Michael Barker of the University of Arizona and colleagues calculate. Such a multiplication occurred in the pine family about 342 million to 200 million years ago. The extra DNA may have helped conifers survive the Permian-Triassic extinction about 252 million years ago, the researchers speculate.

Tina Hesman Saey is the senior staff writer and reports on molecular biology. She has a Ph.D. in molecular genetics from Washington University in St. Louis and a master’s degree in science journalism from Boston University.

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