Comparative Genetic Mapping Between Octoploid and Diploid Fragaria Species Reveals a High Level of Colinearity Between Their Genomes and the Essentially Disomic Behavior of the Cultivated Octoploid Strawberry

Abstract

Macrosynteny and colinearity between Fragaria (strawberry) species showing extreme levels of ploidy have been studied through comparative genetic mapping between the octoploid cultivated strawberry (F. 3ananassa) and its diploid relatives. A comprehensive map of the octoploid strawberry, in which almost all linkage groups are ranged into the seven expected homoeologous groups was obtained, thus providing the first reference map for the octoploid Fragaria. High levels of conserved macrosynteny and colinearity were observed between homo(eo)logous linkage groups and between the octoploid homoeologous groups and their corresponding diploid linkage groups. These results reveal that the polyploidization events that took place along the evolution of the Fragaria genus and the more recent juxtaposition of two octoploid strawberry genomes in the cultivated strawberry did not trigger any major chromosomal rearrangements in genomes involved in F. 3ananassa. They further suggest the existence of a close relationship between the diploid Fragaria genomes. In addition, despite the possible existence of residual levels of polysomic segregation suggested by the observation of large linkage groups in coupling phase only, the prevalence of linkage groups in coupling/repulsion phase clearly demonstrates that the meiotic behavior is mainly disomic in the cultivated strawberry.

Metabolite profiling reveals novel multi-level cold responses in the diploid model Fragaria vesca (woodland strawberry)

“…However, a high degree of genome colinearity between diploid and octoploid Fragaria sp. exists (Rousseau-Gueutin et al, 2008), and plant biological processes including metabolic regulation under low temperature conditions were likely to be highly similar in both species.…”

Comparative Genetic Mapping Points to Different Sex Chromosomes in Sibling Species of Wild Strawberry (Fragaria)

“…Recent genetic maps have revealed macrosynteny between the diploid and octoploid genomes (Rousseau-Gueutin et al 2008;Sargent et al 2009;Spigler et al 2010), allowing the autosomal homeolog of the proto-sex chromosome of subdioecious F. virginiana to be identified . Our study takes advantage of this published work to begin to answer the overarching question: Is the sex-determining region of dioecious F. chiloensis syntenous with that of its sibling species, subdioecious F. virginiana?…”

“…chiloensis and F. virginiana are allo-allopolyploids (Bringhurst 1990) with disomic inheritance (2n ¼ 8x ¼ 56) (Ashley et al 2003;Lerceteau-Kö hler et al 2003;Rousseau-Gueutin et al 2008). The two species share a very recent common ancestor (RousseauGueutin et al 2009;Njuguna 2010) and are thought to have diverged only after migration across the Bering Strait to northwestern North America from Asia (Staudt 1999), where F. virginiana dispersed eastward and F. chiloensis southward.…”

Genetic investigation of the origination of allopolyploid with virtually synthesized lines: Application to the C subgenome of Brassica napus

“…However, these changes are much fewer than the genetic differences between the genomes of the parental species (Comai et al, 2000;Ozkan et al, 2001;Kashkush et al, 2002;Parkin et al, 2003;Rana et al, 2004;Lukens et al, 2006;Rousseau-Gueutin et al, 2008). Given that there are high degrees of macrosynteny and colinearity between an allopolyploid and its progenitors, the majority of genetic characteristics of the progenitor species are maintained in the allopolyploid during its generation and evolution (Rana et al, 2004;RousseauGueutin et al, 2008).…”