January 15-19, 2011
Town & Country Convention Center
San Diego, CA
Samuel Amiteye1 , Heiko Vogel2 , Timothy F. Sharbel1
Apomixis, a natural form of reproduction in plants whereby seeds are produced asexually, is hypothesized to result from the deregulation of developmental pathways leading to sexual seed development. Hypotheses seeking to explain the trigger for deregulation employ the global genomic effects of hybridization and polyploidy. We are interested in the first step of apomixis, the production of meiotically unreduced gametes (apomeiosis). Using transcriptomal profiling of microdissected live tissues from multiple sexual and apomictic Boechera accessions, we have demonstrated heterochrony, whereby gene expression patterns are shifted between sexual and apomictic ovules. We have also shown that apomixis-specific gene expression is characterized by a significant overrepresentation of transcription factor activity. We are now examining miRNAs and their correlation with heterochrony, since we hypothesize that apomeiosis is influenced by the relative titer of trans-acting regulatory factors, which is effectively halved in the hybrid (apomictic) genome due to divergent transcriptional regulator and promoter sequence evolution in the parental genomes. We have thus cloned and sequenced over 1000 different miRNAs, followed by verification experiments to assess their putative action. Interestingly, we have identified a number of classes of miRNA which specifically target regulatory factors, and hence this may represent another level of gene regulation which could tentatively help elucidate the correlation between hybridization and apomixis in Boechera.