Project description:Investigation of genome-wide gene expression in sepals, petals, stamens, staminodia and carpels in pre-anthesis Aquilegia flowers. One goal was to identify transcriptional signatures associated with petaloidy by comparing gene expression in petals and petaloid sepals. Other goals were to study the evolutionary origin and ecological function of staminodia by comparing a) expression patterns in stamens, staminodia and carpels, b) identifying transcriptional regulators expressed in staminodia and c) using gene set enrichment analysis to identify biological processes operating in staminodia.
Project description:Investigation of genome-wide gene expression in sepals, petals, stamens, staminodia and carpels in pre-anthesis Aquilegia flowers. One goal was to identify transcriptional signatures associated with petaloidy by comparing gene expression in petals and petaloid sepals. Other goals were to study the evolutionary origin and ecological function of staminodia by comparing a) expression patterns in stamens, staminodia and carpels, b) identifying transcriptional regulators expressed in staminodia and c) using gene set enrichment analysis to identify biological processes operating in staminodia. A 15 chip study using total RNA from the five floral tissues from three replicate natural populations with each sample representing tissue pooled from 60 flowers.
Project description:We report the investigation of an Aquilegia flavescens × A. formosa population in British Columbia that is disjunct from its parents-the latter species is present locally but ecologically separated, while the former is entirely absent. To confirm hybridity, we used multivariate analysis of floral characters of field-sampled populations to ordinate phenotypes of putative hybrids in relation to those of the parental species. Microsatellite genotypes at 11 loci from 72 parental-type and putative hybrid individuals were analysed to assess evidence for admixture. Maternally inherited plastid sequences were analysed to infer the direction of hybridization and test hypotheses on the origin of the orphan hybrid population. Plants from the orphan hybrid population are on average intermediate between typical A. formosa and A. flavescens for most phenotypes examined and show evidence of genetic admixture. This population lies beyond the range of A. flavescens, but within the range of A. formosa. No pure A. flavescens individuals were observed in the vicinity, nor is this species known to occur within 200 km of the site. The hybrids share a plastid haplotype with local A. formosa populations. Alternative explanations for this pattern are evaluated. While we cannot rule out long-distance pollen dispersal followed by proliferation of hybrid genotypes, we consider the spread of an A. formosa plastid during genetic swamping of a historical A. flavescens population to be more parsimonious.
Project description:BackgroundFlowering is a critical transition in plant development, the timing of which can have considerable fitness consequences. Until recently, research into the genetic control of flowering time and its associated developmental changes was focused on core eudicots (for example, Arabidopsis) or monocots (for example, Oryza). Here we examine the flowering response of Aquilegia formosa, a member of the eudicot order Ranunculales that is emerging as an important model for the investigation of plant ecology and evolution.ResultsWe have determined that A. formosa has a strong vernalization requirement but little or no photoperiod response, making it a day neutral (DN) plant. Consistent with this, the Aquilegia homolog of FLOWERING LOCUS T (AqFT) is expressed in both long and short days but surprisingly, the locus is expressed before the transition to flowering. In situ hybridizations with homologs of several Arabidopsis Floral Pathway Integrators (FPIs) do not suggest conserved functions relative to Arabidopsis, the potential exceptions being AqLFY and AqAGL24.2.ConclusionsIn Aquilegia, vernalization is critical to flowering but this signal is not strictly required for the transcriptional activation of AqFT. The expression patterns of AqLFY and AqAGL24.2 suggest a hypothesis for the development of Aquilegia's determinate inflorescence whereby their differential expression controls the progression of each meristem from inflorescence to floral identity. Interestingly, none of the Aquilegia expression patterns are consistent with a function in floral repression which, combined with the lack of a FLC homolog, means that new candidate genes must be identified for the control of vernalization response in Aquilegia.
Project description:Flowering in plants is a very dynamic and synchronized process where various cues including age, day-length, temperature and endogenous hormones fine-tune the timing of flowering for reproductive success. Arabidopsis thaliana is a facultative long day plant where long-day (LD) photoperiod promotes flowering. Arabidopsis still flowers under short-day (SD) conditions, albeit much later than LD conditions. Although, factors regulating the photoperiodic LD pathway have been extensively investigated, the SD pathway is much less understood. Here we identified a critical transcription factor called bHLH93 (basic Helix-Loop-Helix 93) that is essential to induce flowering specifically under SD conditions in Arabidopsis. bhlh93 mutants do not flower from primary meristem under SD conditions, but flowers similar to wild type under LD conditions. The late flowering phenotype is rescued by exogenous application of GA, suggesting that bHLH93 acts upstream of GA pathway to promote flowering. Double mutant studies showed that bhlh93 is epistatic to phyB and soc1 genes under SD conditions. bHLH93 is expressed at the meristematic regions and its expression peaks at 8 hours after dawn under SD conditions. As expected, the bHLH93 is localized in the nucleus. Taken together, these data suggest that bHLH93 is a key transcription factor necessary for Arabidopsis thaliana to evolve as a facultative plant.
Project description:Flowering in plants is a very dynamic and synchronized process where various cues including age, day-length, temperature and endogenous hormones fine-tune the timing of flowering for reproductive success. Arabidopsis thaliana is a facultative long day plant where long-day (LD) photoperiod promotes flowering. Arabidopsis still flowers under short-day (SD) conditions, albeit much later than LD conditions. Although, factors regulating the photoperiodic LD pathway have been extensively investigated, the SD pathway is much less understood. Here we identified a critical transcription factor called bHLH93 (basic Helix-Loop-Helix 93) that is essential to induce flowering specifically under SD conditions in Arabidopsis. bhlh93 mutants do not flower from primary meristem under SD conditions, but flowers similar to wild type under LD conditions. The late flowering phenotype is rescued by exogenous application of GA, suggesting that bHLH93 acts upstream of GA pathway to promote flowering. Double mutant studies showed that bhlh93 is epistatic to phyB and soc1 genes under SD conditions. bHLH93 is expressed at the meristematic regions and its expression peaks at 8 hours after dawn under SD conditions. As expected, the bHLH93 is localized in the nucleus. Taken together, these data suggest that bHLH93 is a key transcription factor necessary for Arabidopsis thaliana to evolve as a facultative plant. Stratified Col-0 and bhlh93-1 mutants seeds in cold for 4 days. Transferred to Short Day (8h light and 16h dark) chamber and harvested samples after 10days. Tissue was harvested 0 and 4 hour after light was turned on.