Reconstructing the ancestral karyotypes of S. rosmarinus, S. miltiorrhiza and S. splendens
AEK (ancestral eudicot karyotype) was reconstructed from a grape–cacao–peach comparison , and obtained seven protochromosomes with 6,284 ordered protogenes. AEK genome was used for karyotype projections of S. rosmarinus , S. miltiorrhiza and S. splendens . To obtain the karyotype changes of species, we inferred the possible chromosomal evolution process through the comparison of homologous regions between species and AEK genome, and represented seven protochromosomes with different colors.
Karyotype projections indicated the large amount of chromosomal rearrangements occurred in S. rosmarinus , S. miltiorrhizaand S. splendens . Chromosomes rearrangements occurred along with WGD-2 in S. rosmarinus . The MRCA (most recent common ancestor) ofS. miltiorrhiza and S. splendens could be considered as the ancestor of S. rosmarinus. Collinear homologous regions were identified by blastp in S. miltiorrhiza and S. splendens , based on karyotype projections results, protochromosomes were inferred in MRCA of S. miltiorrhiza and S. splendens . And then chromosomal rearrangements along with WGD-2 were inferred based on karyotype projectory in S. rosmarinus and collinear comparison between S. rosmarinus and S. miltiorrhiza . Finally, we inferred protochromosomes of the MRCA of S. rosmarinus, S. miltiorrhiza and S. splendens , and represented the process of chromosomes karyotype evolution in S. rosmarinus, S. miltiorrhizaand S. splendens .