Biogeographic distribution of polyploidy and B chromosomes in the apomictic Boechera holboellii complex.

Journal Article (Journal Article)

The Boechera holboellii complex comprises B. holboellii and B. drummondii, both of which can reproduce through sex or apomixis. Sexuality is associated with diploid individuals, whereas apomictic individuals are diploid or triploid and may additionally have B chromosomes. Using flow cytometry and karyotype analysis, we have shown that B chromosomes (a) occur in both diploid and triploid apomictic B. holboellii, (b) may occur in triploid B. drummondii, and (c) are dispensable for the plant. Both diploid and triploid karyotypes are found in multiple chloroplast haplotypes of both species, suggesting that triploid forms have originated multiple times during the evolution of this complex. B chromosome carriers are found in geographically and genetically distinct populations, but it is unknown whether the extra chromosomes are shared by common descent (single origin) or have originated via introgressive hybridization and repeated transitions from diploidy to triploidy. Diploid plants containing the Bs reproduce apomictically, suggesting that the supernumerary elements are associated with apomixis. Finally, our analyses of pollen size and viability suggest that irregular chromosome segregation in some triploid lineages may lead to the generation of diploid individuals which carry the B chromosomes.

Full Text

Duke Authors

Cited Authors

  • Sharbel, TF; Mitchell-Olds, T; Dobes, C; Kantama, L; de Jong, H

Published Date

  • January 2005

Published In

Volume / Issue

  • 109 / 1-3

Start / End Page

  • 283 - 292

PubMed ID

  • 15753588

Electronic International Standard Serial Number (EISSN)

  • 1424-859X

International Standard Serial Number (ISSN)

  • 1424-8581

Digital Object Identifier (DOI)

  • 10.1159/000082411


  • eng