The Mediterranean Institute for Advanced Studies (IMEDEA) with the collaboration of the Center for Research in Agricultural Genomics of Barcelona (CRAG) and the University of Oslo (UiO) and with the support of the General Foundation of the CSIC and the funding of the IBEROSTAR Foundation have launched the initiative to sequence the genome of the most important plant (seagrass) in the Mediterranean marine ecosystem and in particular in the Balearic Islands, the posidonia (Posidonia oceanica).

Miquel Gomila (C)

Posidonia oceanica plays a crucial role in carbon fixation and as a keystone species in Mediterranean marine biodiversity, but genetic studies performed so far in this organism are very limited due to the absence of a reference genome. This shortfall is even more notorious in view of imminent climate change and other anthropic impacts. We aim to build a ultra high-quality reference genome and transcriptome of P. oceanica with fully annotated genes and other functional elements involved in different plant processes, such as germination, flowering, photosynthesis, cell division, cell wall elongation and branching. This project will lay the foundations for advanced and comprehensive genetic and gene expression studies at the genomic level with a major impact on conservation and management of this species. In addition, we will annotate chloroplast and mitochondrial genomes to assess the genetic variability of P. oceanica meadows around the Mediterranean in a near future. In order to meet these goals, we will assemble bioinformatically long reads of Posidonia genomic DNA obtained by high-throughput sequencing plus cross-linked chromosomal maps to build a reference genome. We are also going to sequence the transcriptome of four different tissues to identify and annotate genes and other functional elements in the genome, and to perform expression analysis. Such reference genome will provide a list of genes with a key role in different essential plant processes with applications in the conservation and regeneration of P. oceanica meadows by selecting seeds and rhizomes carrying genetic variants highly adapted to local environments, climate change and disturbances. These data will also shed light on past demographic changes in Posidonia due to bottlenecks driven by the Messinian salinity crisis and last glaciation cycles and on the reaction of this species in front of these strong selective pressures.

Jorge Terrados (C)

The aim of this project is to obtain and assemble a high quality reference genome of Posidonia oceanica in order to encourage a paradigm shift in the quantity, quality and magnitude of genetic studies applied to its management and conservation. Specifically, we propose:

1) Obtain the complete genome of P. oceanica (~ 3.1 Gb) where each of the 20 chromosomes is a continuous sequence including centromeres with a curate annotation of genes, RNAs and regulatory areas.

2) Gather the complete transcriptome of roots, leaves, flowers and seeds to identify those genes related to photosynthesis, cell division, cell wall elongation, branching, flowering and germination, as well as tissue-specific differential gene expression.

3) Identify genomic regions under positive selection that could be candidates to environmental adaptations and hence may assist in the regeneration of seagrass –P. oceanica- meadows.