There is an increasing awareness that as a result of structural variation, a reference sequence representing a genome of a single individual is unable to capture all of the gene repertoire found in the species. A large number of genes affected by presence/absence and copy number variation suggest that it may contribute to phenotypic and agronomic trait diversity. Here we show by analysis of the Brassica oleracea pangenome that nearly 20% of genes are affected by presence/absence variation. Several genes displaying presence/absence variation are annotated with functions related to major agronomic traits, including disease resistance, flowering time, glucosinolate metabolism and vitamin biosynthesis.

A resource of resistance genes analogs within Brassicaceae species identifies functional resistance genes to improve plant breeding programmes.

Climate change is impacting ecosystems globally (Pecl et al., 2017) with increasing temperature and extreme climatic events expected to become more frequent, widespread and persistent through the 21st century (Oliver et al., 2019). In many circumstances, climate change is outpacing the ability of species to adapt, causing mortality, range shifts and new ecosystem states (

Polyploidy has the potential to allow organisms to outcompete their diploid progenitor(s) and occupy new environments. Shark Bay, Western Australia, is a World Heritage Area dominated by temperate seagrass meadows including Poseidon's ribbon weed, Posidonia australis . This seagrass is at the northern extent of its natural geographic range and experiences extremes in temperature and salinity. Our genomic and cytogenetic assessments of 10 meadows identified geographically restricted, diploid clones (2 n = 20) in a single location, and a single widespread, high-heterozygosity, polyploid clone (2 n = 40) in all other locations. The polyploid clone spanned at least 180 km, making it the largest known example of a clone in any environment on earth. Whole-genome duplication through polyploidy, combined with clonality, may have provided the mechanism for P. australis to expand into new habitats and adapt to new environments that became increasingly stressful for its diploid progenitor(s). The new polyploid clone probably formed in shallow waters after the inundation of Shark Bay less than 8500 years ago and subsequently expanded via vegetative growth into newly submerged habitats.

In adapting to a marine environment, two independent seagrass lineages lost genes associated with ethylene and terpenoid biosynthesis and retained genes related to salinity adaptation, suggesting habitat-driven convergent evolution.