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Fig. 1 | Genome Biology

Fig. 1

From: Understanding Brassicaceae evolution through ancestral genome reconstruction

Fig. 1

Brassicaceae ancestral genomes and evolutionary scenario. a The extant Brassicaceae genomes as a mosaic of colored blocks that illustrate the ABK1–8 protochromosomes. The number of chromosomes and genes in extant species and reconstructed ancestors (with the number of ordered protogenes followed by the total number of protogenes in parentheses) are given in the figure. The gene gain and loss characterized during Brassicaceae evolution are shown as “ + ” and “-”, respectively, on the tree branches associated with a time scale on the right expressed in millions of years (mya). The hexaploidization of B. rapa is illustrated with a red star . b Dot plot representation of the synteny between the ABK1–8 (color code and y axis) and the extant Brassicaceae (A. thaliana, A. lyrata, C. rubella, B. rapa and T. parvula; x axis). The 24 synteny blocks (A–X) according to the ABC system [6] are shown on the ABK1–8 (y axis) chromosomes. Black arrows and red arrows illustrate reciprocal translations leading to ancestral chromosome fusion with centromere loss (chromosome number reduction) or without centromere loss (no reduction in chromosome number), respectively. c Top: Densities (based on 100-kb physical windows) of annotated genes (red curve), repeats (blue curve), non-ordered protogenes (green curve) and non-protogenes (purple curve) for the extant C. rubella chromosome 8 (corresponding to ABK8, pink). Bottom: Microsynteny between A. thaliana, A. lyrata, C. rubella and T. parvula for a non-ordered protogene density peak highlighted with a vertical black arrow in (b). Conserved genes are linked with black connecting lines. Ancestral genes (on ABK protochromosome 8) retained in extant species are shown as pink boxes and non-ancestral genes as gray boxes and tandemly duplicated genes (i.e., FBD domain-containing protein) as light blue boxes. d Substitution rate (Ks) and dating in millions of years (Mya) (x-axis) of the speciation events (blue horizontal lines) between A. thaliana (At), A. lyrata (Al), C. rubella (Cr), B. rapa (Br) and T. parvula (Tp) (y axis) illustrated as dot boxes

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