Draft genome of Palmaria palmata and intraspecific genetic variations in the North-East Atlantic

The rhodophyte Palmaria palmata (L.) Weber & Mohr is one of the target species of a growing European seaweed industry due to its high content of protein and essential amino acids which makes it suitable for human food, dietary supplements, and as salmon feed. However, the lack of a published nuclear genome limits phylogenetics analyses and gene function investigations which could help the development of a breeding programme. We present the first draft genome of P. palmata that was obtained with PacBio HiFi long read sequencing with average coverage of 10×, consisting of an assembly of 1.05 Gb, N50 = 2.75 Mb and BUSCO completeness of 72.1 %. This is the third largest genome in the Rhodophyta so far, characterized by the highest percentage of repeat elements, 91.3 %. The number of protein coding genes, 9641, two thirds of which are single-exon, is similar to that of other Florideophyceae. This number is far below land plants (ca 25–30,000), and lost protein-coding genes span all biological functions, with the exception of nucleotide metabolism. Reproduction and organogenesis were the most affected, with 98 and 97 % missing genes, respectively. Additionally, a population study on the whole genome of 33 P. palmata individuals from across the Northern East Atlantic area found three main clusters largely consistent with their geographic distribution. These results represent a fundamental step towards breeding and genetic studies to further explore the vastly unexploited economic potential of Palmaria palmata.