Project description:Plants of three different genotypes (FRI FLC, FRI flc and fri flc) were induced to flowering by shifting from short day conditions to long day conditions. FRI=FRIGIDA, FLC=FLOWERING LOCUS C.
Project description:Hight throughput techniques have revealed huge complexity in antisense RNAs in many organisms. We have explored the complexity of this class of transcripts and functional links to Polycomb silencing thought analysis of non-coding RNAs of Arabidopsis FLC. FLC is repressed and epigenetically silenced by prolonged cold, enabling plants to undergo the floral transition. Single nucleotide resolution tiling array revealed long non-coding transcripts covering the entire FLC locus. The most abundant of these are capped and polyadenylated, initiate over a 100 nucleotide window just downstream of the sense polyA site, are differentially spliced and terminate either within the sense gene or its promoter. Their levels correlate with FLC sense transcripts in all mutants and conditions tested except cold treatment. The antisense transcripts were strongly but transiently cold-induced, much earlier than other vernalization markers, and this coincided with reduction in sense FLC transcription but not sense FLC mRNA levels. Addition of the FLC antisense 5'/sense 3' region to a GFP transgene was sufficient to confer cold-induced silencing of thet fusion; however this silencing was not epigenetically manteined. These processes were all independent of the function of the Polycomb proteins required for maintenance of FLC silencing. Our data suggest that FLC antisense transcripts induce transient FLC transcriptional silencing, possibly through promoter interference, with the epigenetic silencing requiring subsequent recruitment of Polycomb machinery. Total seedling RNA from different genotypes and different conditions: WT, FRIGIDA, 35s::FCA (giving overexpression of FCA), FRIGIDA + 2 weeks cold, FRIGIDA + 2 weeks cold + 7 days warm.
