Plant & Animal Genomes XVII Conference Plant & Animal Genomes XVII ConferenceJanuary 10-14, 2009
Town & Country Convention Center
San Diego, CA
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 mechanisms which trigger deregulation employ the global genomic effects of hybridization and polyploidy. Using SuperSAGE, we have identified over 6000 differentially-expressed mRNA tags compared between 10 microdissected live ovules from 2 sexual and 2 diploid apomictic accessions. The genes to which the mRNA tags belong were determined by homology searches to sexual and apomictic flower-specific transcriptome libraries which we sequenced using 454 technology. Our results demonstrate that many of the differentially-expressed mRNAs compared between sexual and apomictic ovules are low copy number, and that both allele-specific expression and microduplication can explain the observed variation between reproductive modes. Our use of deep transcriptomic analyses of live microdissected tissue, in conjunction with massively parallel transcriptome sequencing has thus enabled the identification of a large set of candidate alleles which will be the subject of subsequent analyses of expression profiles at different developmental stages and in different genetic backgrounds. We thus hope to be able to differentiate between population-level variation (i.e. transcriptional noise) and global gene expression differences between sexual and asexual ovules in the near future.