On the origin and evolution of apomixis in Boechera
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The genetic mechanisms causing seed development by gametophytic apomixis in plants are predominantly unknown. As apomixis is consistently associated with hybridity and polyploidy, these confounding factors may either (a) be the underlying mechanism for the expression of apomixis, or (b) obscure the genetic factors which cause apomixis. To distinguish between these hypotheses, we analyzed the population genetic patterns of diploid and triploid apomictic lineages and their sexual progenitors in the genus Boechera (Brassicaceae). We find that while triploid apomixis is associated with hybridization, the majority of diploid apomictic lineages are likely the product of intra-specific crosses. We then show that these diploid apomicts are more likely to sire triploid apomictic lineages than conspecific sexuals. Combined with flow cytometric seed screen phenotyping for male and female components of apomixis, our analyses demonstrate that hybridization is an indirect correlate of apomixis in Boechera.
KeywordsBoechera Apomixis Apomeiosis Hybridization Polyploidy
We thank J. M. Corral and J. Beck for insightful discussions. This work was partially funded by the Apomixis Research Group, using basic level funding provided by the IPK. Additional funding comes from DFG Grant #SH337/7-1 to TFS and a μMorph training Grant to JTL. TMO was supported by NIH Grant R01-GM086496.
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