Sequencing and assembling the mega-genomes of mega-trees: the giant sequoia and coast redwood genomes

Dr. Steven Salzberg, PhD, Johns Hopkins University

The giant sequoia tree (Sequoiadendron giganteum) and the coast redwood (Sequoia sempervirens) are two of the largest living organisms on the planet. A redwood is the world’s tallest tree at 115.7m (379.7 ft), and a sequoia is the world’s most largest, at 1487 cubic meters. These trees also have giant genomes, at 8.2 Gb for sequoia and 26.5 Gb for redwood. Here I’ll describe our successful sequencing and assembly of a 1360-year-old sequoia tree (the tallest known sequoia tree on Earth, at 96.3m) which has produced the largest scaffolds of any genome project ever attempted, including telomere-to-telomere scaffolds for most of the 11 chromosomes. I’ll also describe our near-complete work on the genome of a 1390-year-old coast redwood tree. Both projects used a combination of short reads and long Oxford Nanopore reads for initial assembly, and Hi-C linked reads from Dovetail Genomics for scaffolding.