Bumblebee electric charge stimulates floral volatile emissions in Petunia integrifolia but not in Antirrhinum majus

The timing of volatile organic compound (VOC) emission by flowering plants often coincides with pollinator foraging activity. Volatile emission is often considered to be paced by environmental variables, such as light intensity, and/or by circadian rhythmicity. The question arises as to what extent pollinators themselves provide information about their presence, in keeping with their long co-evolution with flowering plants. Bumblebees are electrically charged and provide electrical stimulation when visiting plants, as measured via the depolarisation of electric potential in the stem of flowers. Here we test the hypothesis that the electric charge of foraging bumblebees increases the floral volatile emissions of bee pollinated plants. We investigate the change in VOC emissions of two bee-pollinated plants (Petunia integrifolia and Antirrhinum majus) exposed to the electric charge typical of foraging bumblebees. P. integrifolia slightly increases its emissions of a behaviorally and physiologically active compound in response to visits by foraging bumblebees, presenting on average 121 pC of electric charge. We show that for P. integrifolia, strong electrical stimulation (600–700 pC) promotes increased volatile emissions, but this is not found when using weaker electrical charges more representative of flying pollinators (100 pC). Floral volatile emissions of A. majus were not affected by either strong (600–700 pC) or weak electric charges (100 pC). This study opens a new area of research whereby the electrical charge of flying insects may provide information to plants on the presence and phenology of their pollinators. As a form of electroreception, this sensory process would bear adaptive value, enabling plants to better ensure that their attractive chemical messages are released when a potential recipient is present.

Phytonutrients and Antioxidant Activity of Extracts from Five Edible Flowers Used in Culinary

The aim of the current study was to evaluate the natural pigments (chlorophylls, carotenoids and anthocyanins), phenolic compounds and antioxidant activity of water and 95% ethanol extracts from five edible flowers - snapdragon (Antirrhinum majus), carnation (Dianthus plumarius), garden geranium (Pelargonium hortorum), petunia (Petunia integrifolia) and dahlia (Dahlia decorative). It was found that water extracts gave higher extractive yields. The highest carotenoids and total anthocyanins content were detected in snapdragon and dahlia flowers. The total phenolic content dominated in water extracts of petunia, garden geranium, carnation and snapdragon - above 30 mg GAE/g of dry extract. Sinapic acid was detected in all edible flowers. Gallic, caffeic, chlorogenic, p-coumaric, rosmarinic, sinapic and ferulic acid were detected only in carnation. Antioxidant activity was the highest in ethanol extracts of petunia, garden geranium, carnation by FRAP method. The current study demonstrated the future application of edible flower extracts as a source of antioxidants for culinary purposes.

HD-AGPs as Speciation Genes: Positive Selection on a Proline-Rich Domain in Non-Hybridizing Species of Petunia, Solanum, and Nicotiana

Transmitting tissue-specific proteins (TTS proteins) are abundant in the extracellular matrix of Nicotiana pistils, and vital for optimal pollen tube growth and seed set. We have identified orthologs from several species in the Solanaceae, including Petunia axillaris axillaris and Petunia integrifolia. We refer to TTS proteins and their orthologs as histidine domain-arabinogalactan proteins (HD-APGs). HD-AGPs have distinctive domains, including a small histidine-rich region and a C-terminal PAC domain. Pairwise comparisons between HD-AGPs of 15 species belonging to Petunia, Nicotiana, and Solanum show that the his-domain and PAC domain are under purifying selection. In contrast, a proline-rich domain (HV2) is conserved among cross-hybridizing species, but variant in species-pairs that are reproductively isolated by post-pollination pre-fertilization reproductive barriers. In particular, variation in a tetrapeptide motif (XKPP) is systematically correlated with the presence of an interspecific reproductive barrier. Ka/Ks ratios are not informative at the infrageneric level, but the ratios reveal a clear signature of positive selection on two hypervariable domains (HV1 and HV2) when HD-AGPs from five solanaceous genera are compared. We propose that sequence divergence in the hypervariable domains of HD-AGPs reinforces sympatric speciation in incipient species that may have first diverged as a consequence of pollinator preferences or other ecological factors.

Sequence Analysis of the Chalcone Synthase Gene Intron in Four Petunia Jussieu Taxa

The sequence of the intron within the chalcone synthase A gene (ChsA) was used to characterize Petunia integrifolia subsp. integrifolia var. depauperata (Fries) Smith et Downs, P. altiplana Ando et Hashimoto, P. littoralis Smith et Downs, and an unknown taxon from the town of Torres in Brazil. Based upon the intron, the Torres taxon most closely resembled P. integrifolia. The unrooted phylogenetic tree suggested that P. integrifolia was more closely related to P. littoralis than P. altiplana.

Arthropod Resistance in a Petunia Ecotype with Glabrous Leaves

A novel ecotype of Petunia integrifolia subsp. integrifolia var. depauperata with glabrous leaves was found near the town of Torres, Brazil, and hybridized with P. ×hybrida. In the F1 and F2 generations, the glabrous leaf trait was quantitatively inherited with high heritability. The absence of trichomes was not associated with the decrease in the resistance of the glabrous-leaved species and hybrids to aphids, but was correlated with a lower resistance to spider mites.

Molecular Heterogeneity of the Chalcone Synthase Intron in Petunia

A method was developed to characterize the genetic heterogeneity of the chalcone synthase gene intron within the Petunia integrifolia (Hook.) Schinz & Thell. species complex. The DNA from wild species collected from known locations was used to amplify the chalcone synthase gene intron through the polymerase chain reaction (PCR). The resulting PCR product was then characterized by Rsa 1 restriction, revealing a degree of heterogeneity that could be used to characterize the species genetically. Of the four different species that were characterized, two could be placed in the same genetic grouping. This study shows that the variation in the intron of the Chs A gene may be species-specific.