2 research outputs found
PetuniaâĂâhybrida floral scent production is negatively affected by highâtemperature growth conditions
Increasing temperatures due to changing global climate are interfering with plantâpollinator mutualism, an interaction facilitated mainly by floral colour and scent. Gas chromatographyâmass spectroscopy analyses revealed that increasing ambient temperature leads to a decrease in phenylpropanoidâbased floral scent production in two PetuniaâĂâhybrida varieties, P720 and Blue Spark, acclimated at 22/16 or 28/22â°C (day/night). This decrease could be attributed to downâregulation of scentârelated structural gene expression from both phenylpropanoid and shikimate pathways, and upâregulation of a negative regulator of scent production, emission of benzenoids V (EOBV). To test whether the negative effect of increased temperature on scent production can be reduced in flowers with enhanced metabolic flow in the phenylpropanoid pathway, we analysed floral volatile production by transgenic âBlue Sparkâ plants overexpressing CaMV 35Sâdriven Arabidopsis thaliana production of anthocyanin pigments 1 (PAP1) under elevated versus standard temperature conditions. Flowers of 35S:PAP1 transgenic plants produced the same or even higher levels of volatiles when exposed to a longâterm highâtemperature regime. This phenotype was also evident when analysing relevant gene expression as inferred from sequencing the transcriptome of 35S:PAP1 transgenic flowers under the two temperature regimes. Thus, upâregulation of transcription might negate the adverse effects of temperature on scent production.We demonstrate that petunia flowers produce less volatile phenylpropanoid compounds, in both scent bouquets and internal pools, in response to elevated temperatures. We reveal that the decrease in floral scent is correlated with reduced transcript levels of scentârelated genes, and that the adverse effect of high temperature can be negated by expressing transcriptional upâregulators. We believe that the conclusions and implications drawn from the original data presented in our manuscript will be of particular interest to a broad spectrum of your readers, particularly in view of recent changes in global climate and the risk of environmental disruption of plantâpollinator mutualism.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/112003/1/pce12486-sup-0001-si.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/112003/2/pce12486.pd
Phenylpropanoid Scent Compounds in Petunia x hybrida Are Glycosylated and Accumulate in Vacuoles
Floral scent has been studied extensively in the model plant Petunia. However, little is known about the intracellular fate of scent compounds. Here, we characterize the glycosylation of phenylpropanoid scent compounds in Petunia x hybrida. This modification reduces scent compounds' volatility, reactivity, and autotoxicity while increasing their water-solubility. Gas chromatographyâmass spectrometry (GCâMS) analyses revealed that flowers of petunia cultivars accumulate substantial amounts of glycosylated scent compounds and that their increasing level parallels flower development. In contrast to the pool of accumulated aglycones, which drops considerably at the beginning of the light period, the collective pool of glycosides starts to increase at that time and does not decrease thereafter. The glycoside pool is dynamic and is generated or catabolized during peak scent emission, as inferred from phenylalanine isotope-feeding experiments. Using several approaches, we show that phenylpropanoid scent compounds are stored as glycosides in the vacuoles of petal cells: ectopic expression of Aspergillus niger β-glucosidase-1 targeted to the vacuole resulted in decreased glycoside accumulation; GCâMS analysis of intact vacuoles isolated from petal protoplasts revealed the presence of glycosylated scent compounds. Accumulation of glycosides in the vacuoles seems to be a common mechanism for phenylpropanoid metabolites