Given the wide variety and horticultural popularity of roses you might find it surprising then that until now there has not been a complete genomic sequence of the rose genus Rosa. In response to this, researchers at The École normale supérieure de Lyon have published a paper in Nature Genetics, detailing the sequence of Rosa chinensis “Old Blush” combined with other sequences from various ancestral species and newer hybrids. The Chinese rose was introduced to Europe in the 18th Century, favoured for its recurrent flowering, colour and scent signatures. This rose was then crossed with a diverse range of other roses to generate the progenitor of modern hybrid roses – the tea rose.
Whilst modern horticultural roses do not have large genomes (560 Mb), they are extremely heterozygous, a side-effect of regular interspecific hybridisation, making fragment assembly difficult and the resulting sequence a patchwork of thousands of scaffolds. For this reason, the approach used in this new paper took almost a decade to develop. The sequence presented by the authors here is the most contiguous generated yet for a plant genome, containing very few gaps and maintaining a high consistency. The authors also annotated the sequence allowing identification of pathways of interest for rose breeding and development.