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Abstract Detail

Bioinformatic and Biometric Methods in Plant Morphology

Little, Stefan [1], Boyes, Ian [1], Von Aderkas, Patrick [1], Ehlting, Jürgen [1].

Transcriptomics-informed ovule development in Pseudotsuga menziesii (Mirb.) Franco (Douglas-fir).

Douglas-fir is an economically important forestry tree whose seed-cone phenology and development is well-studied. The chalcid wasp Megastigmus oviposits into ovules near time of fertilization, manipulating host megagametophytes into nourishing the parasite even in the absence of fertilzation. However, the developmental genetics of normal seed development are largely unknown. We have sampled developing megagametophytes from four stages: pre-pollination, fertilization, early embryo development and mature seed. We compared these stages with unpollinated, unfertilized megagametophytes that resulted in aborted seed. Samples were frozen, RNA extracted, polyadenylated RNA selected and sequenced using paired-end Illumina sequencing. A transcriptome was produced using Trinity, which assembles RNA sequenences de novo/without a reference genome. The assembly contains over four million contigs, approximately 392,000 have sequence similarity to known genes in public databases. Numerous genes are clearly associated with ovule development, and have differential gene expression in pollinated versus unpollinated ovules. Cell-wall modification genes, such as a pectin methylesterases, lichenases, and hydrolases are stage-specific and are associated with major developmental changes in megagametophytes such as production of the corrosion cavity. Several ABA-regulated seed storage genes are highly expressed, late in development, in pollinated ovules only. Stage-specific amino acid, peptide and sugar transporters are found in both treatments. Growth regulator genes found through all samples are similar to those observed in angiosperm seed development. Some of the most compelling results show pollen-related genes in early development of megagametophytes, including genes associated with sporopollenin synthesis, pollen tube growth and chemotropism. In addition, all samples show differential regulation of possible defense response genes and genes associated with programmed cell death.

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1 - University of Victoria, Department of Biology, Victoria, BC, V8W 3N2, Canada

ovule development

Presentation Type: Symposium or Colloquium Presentation
Session: C2
Location: Prince of Wales/Riverside Hilton
Date: Monday, July 29th, 2013
Time: 2:30 PM
Number: C2005
Abstract ID:862
Candidate for Awards:None

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