ALBERT

Description: The mustard family (Brassicaceae) is a scientifically and economically important family, containing the model \nplant Arabidopsis thaliana and numerous crop species that feed billions worldwide. Despite its relevance, \nmost phylogenetic trees of the family are incompletely sampled and often contain poorly supported \nbranches. Here, we present the most complete Brassicaceae genus-level family phylogenies to date (Brassicaceae Tree of Life or BrassiToL) based on nuclear (1,081 genes, 319 of the 349 genera; 57 of the 58 tribes) \nand plastome (60 genes, 265 genera; all tribes) data. We found cytonuclear discordance between the two, \nwhich is likely a result of rampant hybridization among closely and more distantly related lineages. To evaluate the impact of such hybridization on the nuclear phylogeny reconstruction, we performed five different \ngene sampling routines, which increasingly removed putatively paralog genes. Our cleaned subset of 297 \ngenes revealed high support for the tribes, whereas support for the main lineages (supertribes) was moderate. Calibration based on the 20 most clock-like nuclear genes suggests a late Eocene to late Oligocene origin \nof the family. Finally, our results strongly support a recently published new family classification, dividing the \nfamily into two subfamilies (one with five supertribes), together representing 58 tribes. This includes five \nrecently described or re-established tribes, including Arabidopsideae, a monogeneric tribe accommodating \nArabidopsis without any close relatives. With a worldwide community of thousands of researchers working \non Brassicaceae and its diverse members, our new genus-level family phylogeny will be an indispensable tool \nfor studies on biodiversity and plant biology.