Identification and Molecular Mechanisms of Key Nucleotides Causing Attenuation in Pathogenicity of Dahlia Isolate of Potato Spindle Tuber Viroid.

While the potato spindle tuber viroid (PSTVd) variant, PSTVd-Dahlia (PSTVd-D or PSTVd-Dwt) induces very mild symptoms in tomato cultivar 'Rutgers', PSTVd-Intermediate (PSTVd-I or PSTVd-Iwt) induces severe symptoms. These two variants differ by nine nucleotides, of which six mutations are located in the terminal left (TL) to the pathogenicity (P) domains. To evaluate the importance of mutations located in the TL to the P domains, ten types of point mutants were created by swapping the nucleotides between the two viroid variants. Bioassay in tomato plants demonstrated that two mutants created on PSTVd-Iwt at positions 42 and 64 resulted in symptom attenuation. Phenotypic and RT-qPCR analysis revealed that mutation at position 42 of PSTVd-Iwt significantly reduced disease severity and accumulation of the viroid, whereas mutation at position 64 showed a significant reduction in stunting when compared to the PSTVd-Iwt infected plant. RT-qPCR analysis on pathogenesis-related protein 1b1 and chalcone synthase genes showed a direct correlation with symptom severity whereas the expansin genes were down-regulated irrespective of the symptom severity. These results indicate that the nucleotides at positions 42 and 64 are in concert with the ones at positions 43, 310, and 311/312, which determines the slower and stable accumulation of PSTVd-D without eliciting excessive host defense responses thus contributing in the attenuation of disease symptom.

Edible flowers as sources of phenolic compounds with bioactive potential.

The edible flowers are widely used, but there is still a lot to be done in relation to its bioactive potential and its correlation with the presence of phenolic compounds. The aim of this study was determined the individual phenolic profile in the hydromethanolic extracts and infusion preparations of four different flower samples (Dahlia mignon, Rosa damascena 'Alexandria' and R. gallica 'Francesa' draft in R. canina, Calendula officinalis L., and Centaurea cyanus L.) and their bioactive potential (antioxidant, antiproliferative, and antibacterial capacity). All the studied flowers presented different profiles regarding their phenolic composition and revealed biological potential. The bioactive potential of the studied flowers was moderate, the hydromethanolic extracts of rose petals showed the best results for antioxidant and antibacterial assays, while the antiproliferative properties were only present in some of the tested cell lines, for the hydromethanolic extracts, in which dahlia and rose showed the best results. These results demonstrate that edible flowers can be used as a source of phenolic compounds with bioactive potential, which can be applied in the food sector, as foods and as sources natural ingredients.

Nutritional and chemical characterization of edible petals and corresponding infusions: Valorization as new food ingredients.

Edible flowers provide new colours, textures and vibrancy to any dish, and apart from the "glam" factor, they can constitute new sources of bioactive compounds. In the present work, the edible petals and infusions of dahlia, rose, calendula and centaurea, were characterized regarding their nutritional value and composition in terms of hydrophilic and lipophilic compounds. Carbohydrates were the most abundant macronutrients, followed by proteins and ash. Fructose, glucose and sucrose were identified in all the petals and infusions. Rose petals and calendula infusions gave the highest content of organic acids, mainly due to the presence of malic and quinic acids, respectively. Polyunsaturated fatty acids predominated over saturated fatty acids, mainly due to the contribution of linoleic acid. Calendula presented the highest content in tocopherols, with α-tocopherol as the most abundant. These results highlight the interest of edible petals "as" and "in" new food products, representing rich sources of bioactive nutrients.

Identification of insecticidal constituents of the essential oils of Dahlia pinnata Cav. against Sitophilus zeamais and Sitophilus oryzae.

The aim of this research was to determine the chemical composition of the essential oils of Dahlia pinnata, their insecticidal activity against Sitophilus zeamais and Sitophilusoryzae and to isolate insecticidal constituents. Based on bioactivity-guided fractionation, active constituents were isolated and identified as D-limonene, 4-terpineol and α-terpineol. Essential oils and active compounds tested exhibited contact toxicity, with LD50 values ranging from 132.48 to 828.79 µg/cm(2) against S. zeamais and S. oryzae. Essential oils possessed fumigant toxicity against S. zeamais and S. oryzae with LC50 from 14.10 to 73.46 mg/L. d-Limonene (LC50 = 4.55 and 7.92 mg/L) showed stronger fumigant toxicity against target insects. 4-Terpineol (88 ± 8%) and d-limonene (87 ± 5%) showed the strongest repellency against S. zeamais and S. oryzae, respectively. The results indicate that essential oils and insecticidal constituents have potential for development into natural fumigants, insecticides or repellents for control of the stored-product insect pests.

Production of inulinase, fructosyltransferase and sucrase from fungi on low-value inulin-rich substrates and their use in generation of fructose and fructo-oligosaccharides.

Owing to applications in the food and nutraceutical industries, inulinases, fructosyltransferases and sucrases have gained considerable attention in recent times. Twenty-five fungal strains were screened for production of these enzymes on three different media formulated using inulin-rich plant extracts prepared from asparagus root, dahlia tuber and dandelion root extract. Culture filtrates of the fungi were examined for hydrolytic activities. Fungi belonging to genus Aspergillus, A. niger GNCC 2655 (11.3 U/ml), A. awamori MTCC 2879 (8.2 U/ml), A. niger ATCC 26011 (7.9 U/ml) secreted high titers of inulinase followed by Penicillium sp. NFCCI 2768 (2.6 U/ml) and Penicillium citrinum MTCC 1256 (1.1 U/ml). High sucrase activity was noticed in A. niger GNCC 2613 (113 U/ml) and A. awamori MTCC 2879 (107.8 U/ml). Analysis of end products of inulinase action by HPLC revealed that most of the enzymes were exo-inulinases liberating fructose exclusively from inulin. Five fungi, P. citrinum MTCC 1256, Penicillium rugulosum MTCC 3487, Penicillium sp. NFCCI 2768, A. fumigatus GNCC 1351 and A. niger ATCC 26011 however, produced a mixture of endo- and exo-inulinases liberating oligosaccharides (GF3 and GF2) along with fructose. High inulinase/sucrase yielding strains were evaluated for extracellular and intracellular hydrolytic and transfructosylating activities and intracellular enzyme profiles were found to be considerably different in terms of titers and end products.

Fructo-oligosaccharide production from inulin through partial citric or phosphoric acid hydrolyses.

Purified inulin from Dahlia tubers was partially hydrolyzed to form fructo-oligosaccharides by using citric or phosphoric acids (pH, 2.0-2.5) as mild acid catalysts. The ideal kinetic conditions to ensure a high yield of fructo-oligosaccharides relative to free fructose were a temperature range of 85°C-95°C, a hydrolysis time of 15-25 minutes, and a catalyst pH of 2.5. At the higher temperature and the longest hydrolysis time, an inversion of the product ratio occurred. Under these conditions, co-generation of hydroxymethylfurfural occurred, and it was eliminated by activated charcoal. Unlike in classic hydrolysis with hydrochloric or sulfuric acid, deionization of the actual hydrolysates was not necessary because the catalyst neutralization with common bases results in the formation of co-nutrients with alternative uses as foods or fermentation substrates. These whole hydrolysates can be advantageously added as nutraceuticals to carbonated beverages and acidic foods, such as soft drinks and yogurts.

Delta inulin: a novel, immunologically active, stable packing structure comprising ß-D-[2 -> 1] poly(fructo-furanosyl) α-D-glucose polymers.

We report a novel isoform of ß-D-[2 → 1] poly(fructo-furanosyl) α-D-glucose termed delta inulin (DI), comparing it with previously described alpha (AI), beta (BI) and gamma (GI) isoforms. In vitro, DI is the most immunologically active weight/weight in human complement activation and in binding to monocytes and regulating their chemokine production and cell surface protein expression. In vivo, this translates into potent immune adjuvant activity, enhancing humoral and cellular responses against co-administered antigens. As a biocompatible polysaccharide particle, DI is safe and well tolerated by subcutaneous or intramuscular injection. Physico-chemically, DI forms as an insoluble precipitate from an aqueous solution of suitable AI, BI or GI held at 37-48°C, whereas the precipitate from the same solution at lower temperatures has the properties of AI or GI. DI can also be produced by heat conversion of GI suspensions at 56°C, whereas GI is converted from AI at 45°C. DI is distinguished from GI by its higher temperature of solution in dilute aqueous suspension and by its lower solubility in dimethyl sulfoxide, both consistent with greater hydrogen bonding in DI's polymer packing structure. DI suspensions can be dissolved by heat, re-precipitated by cooling as AI and finally re-converted back to DI by repeated heat treatment. Thus, DI, like the previously described inulin isoforms, reflects the formation of a distinct polymer aggregate packing structure via reversible noncovalent bonding. DI forms the basis for a potent new human vaccine adjuvant and further swells the growing family of carbohydrate structures with immunological activity.