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Hybridization‐facilitated genome merger and repeated chromosome fusion after 8 million years
Author(s) -
Mandáková Terezie,
Guo Xinyi,
Özüdoğru Barış,
Mummenhoff Klaus,
Lysak Martin A.
Publication year - 2018
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.14065
Subject(s) - biology , genome , chromosomal rearrangement , clade , genetics , chromosome , evolutionary biology , myr , phylogenetics , karyotype , gene
Summary The small genus Ricotia (nine species, Brassicaceae) is confined to the eastern Mediterranean. By comparative chromosome painting and a dated multi‐gene chloroplast phylogeny, we reconstructed the origin and subsequent evolution of Ricotia . The ancestral Ricotia genome originated through hybridization between two older genomes with n = 7 and n = 8 chromosomes, respectively, on the Turkish mainland during the Early Miocene ( c . 17.8 million years ago, Ma). Since then, the allotetraploid ( n = 15) genome has been altered by two independent descending dysploidies ( DD ) to n = 14 in Ricotia aucheri and the Tenuifolia clade (2 spp.). By the Late Miocene ( c . 10 Ma), the latter clade started to evolve in the most diverse Ricotia core clade (6 spp.), the process preceded by a DD event to n = 13. It is noteworthy that this dysploidy was mediated by a unique chromosomal rearrangement, merging together the same two chromosomes as were merged during the origin of a fusion chromosome within the paternal n = 7 genome c . 20 Ma. This shows that within a time period of c . 8 Myr genome evolution can repeat itself and that structurally very similar chromosomes may originate repeatedly from the same ancestral chromosomes by different pathways (end‐to‐end translocation versus nested chromosome insertion).