Transcriptomic analysis of Douglas-fir megagametophyte development and abortion




Boyes, Ian

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Douglas-fir develops a megagametophyte regardless of the pollination state of the ovule, whereas many other conifers develop a megagametophye in response to polli- nation. Megagametophytes in unfertilized ovules degrade two weeks following fertil- ization of the surrounding population. This is mediated by programmed cell death (PCD). Pollinated and unpollinated megagametophytes were dissected from Douglas- fir cones and extracted for RNA, which was then used as input for sequencing. A transcriptome was assembled from this data and expression levels were calculated. The data were fitted to quadratic regressions to produce coexpression groups. There is no clear upregulation of PCD effectors in the unpollinated megagametophyte. Po- tential regulators of megagametophyte fate are present in the data. Some are as- sociated with ABA signalling and proanthocyanadin biosynthesis while others share similarity to known regulators of PCD. Seed development processes are represented in the expression data, which support current knowledge of conifer seed development and provide targets for research.



Douglas-fir, seed, ovule, megagametophyte, gymnosperm, conifer, Megastigmus, pollen, pollination, abortion, embryo, ABySS, RSEM, proanthyocyanidin, transcriptome