Dahlia Variabilis Research Articles

Optimasi Produksi Inulinase oleh Khamir Pichia manshurica DUCC Y-015 pada Tepung Umbi Dahlia (Dahlia variabilis Willd.) dengan Variasi Konsentrasi K2HPO4 dan Waktu Inkubasi

Sugar national supply more and more decreases and can not meet the market needs. The research has been done to find alternative natural sweeteners including inulin from dahlia tubers (D. variabilis Willd). Dahlia tuber can produce 95% of yield of fructose syrup in an enzimatic reaction by inulinase (E.C.3.2.1.7). Inulinase is inductive enzyme that can be produce by P. manshurica. The production of fructose needs to be optimized to get optimum product. The optimization can be done by modifying the nutrient content in the medium such as K2HPO4 and variation of incubation time. The purpose of this study is to determine the concentration of K2HPO4 and optimum incubation time for P. manshurica. This research was conducted in Microbiology Laboratory, Biology Department, Faculty of Science and Mathematics Undip. The examined variable is the growth of yeast cell, inulinase activity, invertase, and the I/S ratio. This research was conducted experimentally using Randomized Complete Block Design (RCBD) factorial pattern with 2 factors, the first factor was the concentration of K2HPO4 (P), with concentration level (g/L) of 0.5 (P1), 1.0 (P2), and 1.5 (P3). The second factor was incubation time (W) with 12 hours (W12), 18 hours (W18), and 24 hours (W24). Every treatment was repeated three times. The collected data were analyzed using ANOVA. If there was a treatment effect, it will be continued with Duncan test on 5% significance level. The result of analysis show that the highest cell growth and the maximum production of inulinase enzyme was in P3W24 occurs in P3W24 (K2HPO4 1.5 g/L and 24 hours incubation time) treatment at 0.428 IU, but efficient in P1W12 treatment as much as 0.365 IU. Keywords: Dahlia variabilis Willd., Inulinase, K2HPO4, Pichia manshurica DUCC Y-015, incubation time

Phylogenetic distribution of an endogenous strain of Dahlia mosaic virus in members of Asteraceae

Dahlia mosaic virus (DMV) is a double-stranded DNA viral pathogen. A newly discovered strain of this virus called DMV-D10 was first observed in Dahlia variabilis. DMV-D10 does not induce visible symptoms of infection in the host plant, and is classified as an endogenous pararetrovirus. These viruses have the ability to integrate their viral sequences into the host plant genome, which can be transmitted vertically to offspring. Currently, no studies have examined the host range of DMV-D10. Because DMV-D10 has only been observed in Dahlia, the objective for this study was to determine if presence of DMV-D10 follows an evolutionary relationship among species closely related to Dahlia. It was hypothesized species in the same tribe (Coreopsideae) as Dahlia, such as Cosmos, were more likely to be infected with DMV-D10 compared to species within other tribes in the Asteraceae family. PCR results for a movement protein gene indicate DMV-D10 is more widely spread across Asteraceae than in Dahlia species. DMV-D10 was present in Callistephus chinensis (Astereae tribe), Centaurea cyanus (Cardueae tribe), and Dahlia variabilis (Coreopsideae tribe), but not in Tagetes erecta (Tageteae tribe) or Cosmos bipinnatus (Coreopsideae tribe). Therefore, phylogenetic relationship in host plants does not necessarily determine presence or absence of DMV-D10. This leads to questions of how this virus can move to other species in other tribes. Future work will further explore host range, and if there are physiological symptoms associated with DMV-D10 infection.

M&M reports on animal feed pigments, cosmetic colrants & plastics masterbatch

The spectral quality of photoperiodic lighting can affect flowering of short-day plants (SDPs) and long-day plants (LDPs) differently. When delivered during the middle of the night (night interruption, NI), red (R; 600–700 nm) light alone can inhibit flowering of SDPs, whereas a combination of R and far-red (FR; 700–800 nm) light promotes flowering of some LDPs. However, whether or not low-intensity (≈1–2 μmol m−2 s−1) blue (B; 400–500 nm) light, when added to R and/or FR light, influences flowering has not been established. We investigated the effects of mixed B, R, and FR light on flowering of five SDPs [chrysanthemum (Chrysanthemum × morifolium), cosmos (Cosmos sulfureus), two cultivars of dahlia (Dahlia pinnata), and marigold (Tagetes erecta)] and two LDPs [dianthus (Dianthus chinensis) and rudbeckia (Rudbeckia hirta)]. Plants were grown in a greenhouse at a constant set point of 20 °C and received a truncated 9-h short day (SD) with or without 4-h NI lighting from incandescent (INC) lamps or white (W), B, B + R, B + FR, B + R + FR, or R + FR light-emitting diodes (LEDs). Each NI lighting treatment delivered a mean photon flux of 1.5 μmol m−2 s−1 between 400 and 800 nm at plant height. Blue light alone was not perceived as a long day by all SDPs and LDPs tested. For all SDPs, W LEDs inhibited flowering most effectively. B + R NI was as effective as W NI at creating a long day for all SDPs except chrysanthemum. B + FR NI inhibited flowering of marigold and dahlia ‘Leanne’, but not chrysanthemum or dahlia ‘Gallery Pablo’. For marigold, B + FR NI was less effective than other NI lighting treatments with R light. B + R + FR and R + FR NI similarly delayed flowering of all SDPs except dahlia ‘Gallery Pablo’. NI lighting treatments containing R light similarly promoted flowering of rudbeckia. We conclude that in at least the crops studied, low-intensity B light during the night does not influence flowering. In addition, W LEDs that emit little FR light are effective at creating long days for SDPs but only some LDPs.

Tobacco streak virus (strain dahlia) suppresses post-transcriptional gene silencing of flavone synthase II in black dahlia cultivars and causes a drastic flower color change.

Tobacco streak virus suppressed post-transcriptional gene silencing and caused a flower color change in black dahlias, which supported the role of cyanidin-based anthocyanins for black flower appearance. Black flower color of dahlia (Dahlia variabilis) has been attributed, in part, to the high accumulation of cyanidin-based anthocyanins that occurs when flavone synthesis is reduced because of post-transcriptional genesilencing (PTGS) of flavone synthase II (DvFNS). There are also purple-flowering plants that have emerged from a black cultivar 'Kokucho'. We report that the purple color is not caused by a mutation, as previously thought, but by infection with tobacco streak virus (TSVdahlia), which suppresses the PTGS of DvFNS. When TSVdahlia was eliminated from the purple-flowering 'Kokucho' by leaf primordia-free shoot apical meristem culture, the resulting flowers were black. TSVdahlia-infected purple flowers had lower numbers of siRNAs to DvFNS than black flowers, suggesting that TSVdahlia has a silencing suppressor. The graft inoculation of other black cultivars with TSVdahlia altered their flower color drastically except for 'Fidalgo Blacky', a very deep black cultivar with the highest amount of cyanidin-based anthocyanins. The flowers of all six TSVdahlia-infected cultivars accumulated increased amounts of flavones and reduced amounts of cyanidin-based anthocyanins. 'Fidalgo Blacky' remained black despite the change in pigment accumulation, and the amounts of cyanidin-based anthocyanins in its TSVdahlia-infected plants were still higher than those of other cultivars. We propose that black flower color in dahlia is controlled by two different mechanisms that increase the amount of cyanidin-based anthocyanins: DvFNS PTGS-dependent and -independent mechanisms. If both mechanisms occur simultaneously, the flower color will be blacker than if only a single mechanism is active.

Characterization and comparative analysis of promoters from three plant pararetroviruses associated with Dahlia (Dahlia variabilis).

Two distinct caulimoviruses, Dahlia mosaic virus (DMV) and Dahlia common mosaic virus (DCMV), and an endogenous plant pararetroviral sequence (DvEPRS, formerly known as DMV-D10) were reported from dahlia (Dahlia spp). Promoter elements from these dahlia-associated pararetroviruses were identified and characterized. The TATA box, the CAAT box, the transcription start site, the polyadenylation signal, and regulation factors, characteristic of caulimovirus promoters, were present in each of these promoter regions. Each of the promoter regions was separately cloned into a binary vector containing β-glucuronidase (GUS) reporter gene and delivered into Agrobacterium tumefaciens by electroporation followed by agroinfiltration into Nicotiana benthamiana. The activity of the 35S promoter homologs was determined by transient expression of the GUS gene both in qualitative and quantitative assays. The length of the promoter regions in DMV, DCMV, and DvEPRS corresponded to 438, 439, and 259 bp, respectively. Quantitative GUS assays showed that the promoters from DMV and DCMV resulted in higher levels of gene expression compared to that of DvEPRS in N. benthamiana leaf tissue. Significant differences were observed among the three promoters (p < 0.001). Qualitative GUS assays were consistent with quantitative GUS results. This study provides important information on new promoters for prospect applications as novel promoters for their potential use in foreign gene expression in plants.

Low-intensity blue light in night-interruption lighting does not influence flowering of herbaceous ornamentals

The spectral quality of photoperiodic lighting can affect flowering of short-day plants (SDPs) and long-day plants (LDPs) differently. When delivered during the middle of the night (night interruption, NI), red (R; 600–700nm) light alone can inhibit flowering of SDPs, whereas a combination of R and far-red (FR; 700–800nm) light promotes flowering of some LDPs. However, whether or not low-intensity (≈1–2μmolm−2s−1) blue (B; 400–500nm) light, when added to R and/or FR light, influences flowering has not been established. We investigated the effects of mixed B, R, and FR light on flowering of five SDPs [chrysanthemum (Chrysanthemum×morifolium), cosmos (Cosmos sulfureus), two cultivars of dahlia (Dahlia pinnata), and marigold (Tagetes erecta)] and two LDPs [dianthus (Dianthus chinensis) and rudbeckia (Rudbeckia hirta)]. Plants were grown in a greenhouse at a constant set point of 20°C and received a truncated 9-h short day (SD) with or without 4-h NI lighting from incandescent (INC) lamps or white (W), B, B+R, B+FR, B+R+FR, or R+FR light-emitting diodes (LEDs). Each NI lighting treatment delivered a mean photon flux of 1.5μmolm−2s−1 between 400 and 800nm at plant height. Blue light alone was not perceived as a long day by all SDPs and LDPs tested. For all SDPs, W LEDs inhibited flowering most effectively. B+R NI was as effective as W NI at creating a long day for all SDPs except chrysanthemum. B+FR NI inhibited flowering of marigold and dahlia ‘Leanne’, but not chrysanthemum or dahlia ‘Gallery Pablo’. For marigold, B+FR NI was less effective than other NI lighting treatments with R light. B+R+FR and R+FR NI similarly delayed flowering of all SDPs except dahlia ‘Gallery Pablo’. NI lighting treatments containing R light similarly promoted flowering of rudbeckia. We conclude that in at least the crops studied, low-intensity B light during the night does not influence flowering. In addition, W LEDs that emit little FR light are effective at creating long days for SDPs but only some LDPs.

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/cm2 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 and properties of inulinase from Penicillium sp. NFCC 2768 grown on inulin-rich vegetal infusions

Inulinase production by Penicillium sp. NFCC 2768 isolated from the rhizosphere soil of dahlia was studied on media containing inulin-rich plant extracts. The maximum inulinase activity (64.54 nkat/ml) was observed with the tuber extract of dahlia (Dahlia pinnata). The fungus produced substantial inulinase activity on asparagus root powder (45.23 nkat/ml) and garlic extracts (41.32 nkat/ml). The apparent molecular weight of the purified inulinase was 68 kDa. The optimum pH and temperature for enzyme activity were 5.0 and 50°C, respectively. Mn2+ and Ca2+ were found to enhance the inulinase activity, while Hg2+ was found to be a strong inhibitor. Inulinase liberated fructose, glucose, sucrose, kestose (GF2), nystose (GF3), and inulooligosaccharides (IOS). This study suggested the use of dahlia tuber extract and asparagus root powder as suitable substrates for inulinase production by the newly isolated Penicillium sp. NFCC 2768, and its application in the generation of fructose and IOS.

Sequence analysis and genetic diversity of five new Indian isolates of cucumber mosaic virus.

Cucumber mosaic virus (CMV) is an important virus since it causes severe losses to many economically important crops worldwide. Five new isolates of CMV were isolated from naturally infected Hippeastrum hybridum, Dahlia pinnata, Hemerocallis fulva, Acorus calamus and Typhonium trilobatum plants, all exhibiting severe leaf mosaic symptoms. For molecular identification and sequence analyses, the complete coat protein (CP) gene of these isolates was amplified by RT-PCR. The resulting amplicons were cloned and sequenced and isolates were designated as HH (KP698590), DP (JF682239), HF (KP698589), AC (KP698588) and TT (JX570732). For study of genetic diversity among these isolates, the sequence data were analysed by BLASTn, multiple alignment and generating phylogenetic trees along with the respective sequences of other CMV isolates available in GenBank Database were done. The isolates under study showed 82-99% sequence diversity among them at nucleotide and amino acid levels; however they showed close relationships with CMV isolates of subgroup IB. In alignment analysis of amino acid sequences of HH and AC isolates, we have found fifteen and twelve unique substitutions, compared to HF, DP and TT isolates, suggesting the cause of high genetic diversity.

Rapid colorimetric detection of Hg2+ ion by green silver nanoparticles synthesized using Dahlia pinnata leaf extract

AbstractIn this study, we for the first time reported green synthesis of silver nanoparticles from silver nitrate solution using leaf extract of

Sequencing and de novo assembly of a Dahlia hybrid cultivar transcriptome.

Dahlia variabilis, with an exceptionally high diversity of floral forms and colors, is a popular flower amongst both commercial growers and hobbyists. Recently, some genetic controls of pigment patterns have been elucidated. These studies have been limited, however, by the lack of comprehensive transcriptomic resources for this species. Here we report the sequencing, assembly, and annotation of the transcriptome of the developing leaves, stems, and floral buds of D. variabilis. This resulted in 35,638 contigs, most of which seem to contain the complete coding sequence, and of which 20,881 could be successfully annotated by similarity to UniProt. Furthermore, we conducted a preliminary investigation to identify contigs with expression patterns consistent with tissue-specificity. These results will accelerate research into the genetic controls of pigmentation and floral form of D. variabilis.

Biological studies of three caulimoviruses associated with dahlia (Dahlia variabilis)

Two distinct caulimoviruses, Dahlia mosaic virus (DMV) and Dahlia common mosaic virus (DCMV), were found to be associated with dahlia mosaic disease. Additionally, an endogenous caulimovirus, Dahlia variabilis endogenous plant pararetroviral sequence (DvEPRS), was found to be present in many cultivated and wild Dahlia spp. Biological properties including mechanical and aphid transmission were investigated for DMV, DCMV and DvEPRS using Verbesina encelioides (crownbeard) as an experimental host. DMV and DCMV were transmitted by Myzus persicae at the rate of 50 and 73%, respectively. DMV and DCMV were mechanically transmissible to V. encelioides and the two effective buffers for mechanical transmission were phosphate buffer (pH 7.0) with nicotinic acid (1%) and sodium bisulfite (5%). Mechanical transmission rates of 58% and 36% were obtained for DMV and DCMV, respectively. DvEPRS was not transmissible by either aphids or mechanical inoculation. Availability of aphid and mechanical inoculation protocols for DMV and DCMV would facilitate further biological studies on caulimoviruses associated with Dahlia.

Comparative analysis of endogenous plant pararetroviruses in cultivated and wild Dahlia spp.

Two distinct caulimoviruses, Dahlia mosaic virus (DMV) and Dahlia common mosaic virus, and an endogenous plant pararetroviral sequence (DvEPRS) were reported in Dahlia spp. DvEPRS, previously referred to as DMV-D10, was originally identified in the US from the cultivated Dahlia variabilis, and has also been found in New Zealand, Lithuania and Egypt, as well as in wild dahlia species growing in their natural habitats in Mexico. Sequence analysis of three new EPRSs from cultivated dahlias from Lithuania [D10-LT; 7,159 nucleotide level (nt)], New Zealand (D10-NZ, 7,156 nt), and the wild species, Dahlia rupicola, from Mexico (D10-DR, 7,133 nt) is reported in this study. The three EPRSs have the structure and organization typical of a caulimovirus species and showed identities among various open reading frames (ORFs) ranging between 71 and 97 % at the nt when compared to those or the known DvEPRS from the US. Examination of a dataset of seven full-length EPRSs obtained to date from cultivated and wild Dahlia spp. provided clues into genetic diversity of these EPRSs from diverse sources of dahlia. Phylogenetic analyses, mutation frequencies, potential recombination events, selection, and fitness were evaluated as evolutionary evidences for genetic variation. Assessment of all ORFs using phylogenomic and population genetics approaches suggests a wide genetic diversity of EPRSs occurring in dahlias. Phylogenetic analyses show that the EPRSs from various sources form one clade indicating a lack of clustering by geographical origin. Grouping of various EPRSs into two host taxa (cultivated vs. wild) shows little divergence with respect to their origin. Population genetic parameters demonstrate negative selection for all ORFs, with the reverse transcriptase region more variable than other ORFs. Recombination events were found which provide evolutionary evidence for genetic diversity among dahlia-associated EPRSs. This study contributes to an increased understanding of molecular population genetics and evolutionary pathways of these reverse transcribing viral elements.

Penambahan Filtrat Tepung Umbi Dahlia (Dahlia variabilis Willd.) sebagai Prebiotik dalam Pembuatan Yoghurt Sinbiotik

Yoghurt is a fermented milk product that can provide beneficial effects to the health of consumers. Increasing the quality of yoghurt can be made by combining the benefits of probiotic with prebiotic to produce sinbiotic yoghurt. Inulin is a prebiotic that found in many dahlia tuber (Dahlia variabilis Willd.). Pure inulin were expensive, so the alternative is using dahlia tuber flours filtrate as prebiotic ingredients. This study aimed to examine the addition of Dahlia Tuber Flours Filtrate (DTFF) as a prebiotic in sinbiotic yoghurt making using Lactic Acid Bacteria (LAB) Lactobacillus bulgaricus, Streptococcus termophilus dan Lactobacillus acidopilus as probiotic. This research using Completely Randomized Design (CRD) with 4 concentration treatments DTFF 0%, 3%, 6% and 9% with 3 replications. Observed variables consist of the number of total LAB, lactic acid level, pH and organoleptic attributes (aroma, flavor, consistency and impression). Data the number of total LAB, lactic acid level and pH values ​​were analyzed by ANOVA, continued by Duncan test, while the organoleptic data was analyzed by Mann-Whitney U test with 95% significant level. The results showed that the addition of DTFF significantly affect the increasing of total LAB, lactic acid level, organoleptic assessment and decreasing pH of sinbiotic yoghurt. Sinbiotic yoghurt with 3% of DTFF concentration is most preferred by panelists and required the criteria of Indonesian National Standard (SNI) for yoghurt with enough likely aroma, sour taste/specify and enough thick texture with total LAB 2,4 x 108 CFU/ml, 1.3% lactic acid levels and 4.2. pH. Keywords : prebiotic, probiotic, inulin, dahlia tuber, sinbiotic yoghurt, lactobacillus bulgaricus, streptococcus termophilus, lactobacillus acidopilus

Expression of endogenous para-retroviral genes and molecular analysis of the integration events in its plant host Dahlia variabilis

The dahlia (Dahlia variabilis) genome contains an endogenous pararetrovirus sequence (EPRS) tentatively designated as DvEPRS. The DvEPRS shares genome structure and organization that is typical of members of the Caulimovirus genus. Studies were carried out to better understand the nature of this integration and to determine the gene expression of this DvEPRS. Genomic Southern hybridization showed multiple and random integration events of the DvEPRS in the dahlia genome. To investigate the presence of DvEPRS transcripts, RT-PCR was done on DNase-treated total RNA from DvEPRS-infected dahlia plants. Results showed the expression of open reading frames I, V, and VI. Direct PCR from sap extracts produced more intense DNA amplicons of Dahlia mosaic virus and Dahlia common mosaic virus which are believed to exist as typical episomal caulimoviruses, whereas significantly less intense amplicon was seen in case of DvEPRS in comparison with internal transcribed spacer region of dahlias amplicon. The DvEPRS in wild and cultivated species of Dahlia offer a model system to study the molecular events underlying the ecology, evolution and spread of DvEPRS within natural and managed ecosystems and the factors affecting integration of these EPRS in the plant genome.

Cloning and bioinformation analysis of flavone synthase Ⅱ gene of Erigeron breviscapus

Erigeron breviscapus is a medicinal plant with the most developmental potential in Yunnan province, which is belongs to Erigeron genus of Compositae family. Scutellarin, the main active component of Erigeron breviscapus is one of flavone 7-O-glucuronide derivatives, its biosynthesis pathway is still not clear.Full length cDNA encoding flavone syhthase II gene in E. breviscapus was cloned in this study using R-PCR, 3'-RACE and 5'-RACE.The opening reading frame of FS II cDNA of E. breviscapus is 1 557 bp long and encoding 518 amino acids, designed as EbFS II, which is highly homologous with FS II of Compositae species, like Callistephus chinensis, Cynara cardunculus var. scolymus, Gerbera hybrida, Dahlia pinnata and Lobelia erinus.Phylogenetic analysis showed that EbFS II might has the function of directly converting flavanone to flavone.

A basic helix-loop-helix transcription factor DvIVS determines flower color intensity in cyanic dahlia cultivars

The study was aimed to identify the factors that regulate the intensity of flower color in cyanic dahlia (Dahlia variabilis), using fifteen cultivars with different color intensities in their petals. The cultivars were classified into three groups based on their flavonoid composition: ivory white cultivars with flavones; purple and pink cultivars with flavones and anthocyanins; and red cultivars with flavones, anthocyanins, and chalcones. Among the purple, pink, and ivory white cultivars, an inverse relationship was detected between lightness, which was used as an indicator for color intensity and anthocyanin content. A positive correlation was detected between anthocyanin contents and the expression of some structural genes in the anthocyanin synthesis pathway that are regulated by DvIVS, a basic helix-loop-helix transcription factor. A positive correlation between anthocyanin content and expression of DvIVS was also found. The promoter region of DvIVS was classified into three types, with cultivars carrying Type 1 promoter exhibited deep coloring, those carrying Type 2 and/or Type 3 exhibited pale coloring, and those carrying Type 1 and Type 2 and/or Type 3 exhibited medium coloring. The transcripts of the genes from these promoters encoded full-length predicted proteins. These results suggested that the genotype of the promoter region in DvIVS is one of the key factors determining the flower color intensity.

First report of powdery mildew on Dahlia (Dahlia variabilis) caused by Golovinomyces cichoracearum in Lahore, Pakistan

Dahlia (Dahlia variabilis Desf.) plants infected by powdery mildew were collected from different areas of Lahore Pakistan, in April 2011. Infected plants leaves surfaces were covered with white mycelium. The powdery mildew patches were slightly whitish gray with cylindric to doliform, hyaline conidia borne in chains. The conidia were 30–50 μm long × 14–20 μm wide. Conidiophores were unbranched, 110–220 long × 6–13 μm wide, composed of a foot cell and three to eight barrel-shaped conidia. Foot cells were 55–90 μm long and 6–13 μm wide, slightly swollen with constriction at the base. The cleistothecia were not observed. Fibrosin bodies were absent in conidiophores and conidia. Morphological characteristics and pathogenicity test confirmed the identification as Golovinomyces cichoracearum (DC.) V.P. Heluta. This is thought to be the first report of G. cichoracearum on D. variabilis in Pakistan.

Endogenous post-transcriptional gene silencing of flavone synthase resulting in high accumulation of anthocyanins in black dahlia cultivars

Black color in flowers is a highly attractive trait in the floricultural industry, but its underlying mechanisms are largely unknown. This study was performed to identify the bases of the high accumulation of anthocyanidins in black cultivars and to determine whether the high accumulation of total anthocyanidins alone leads to the black appearance. Our approach was to compare black dahlia (Dahlia variabilis) cultivars with purple cultivars and a purple flowering mutant of a black cultivar, using pigment and molecular analyses. Black cultivars characteristically exhibited low lightness, high petal accumulation of cyanidin and total anthocyanidins without flavones, and marked suppression of flavone synthase (DvFNS) expression. A comparative study using black and purple cultivars revealed that neither the absence of flavones nor high accumulation of total anthocyanidins is solely sufficient for black appearance, but that cyanidin content in petals is also an important factor in the phenotype. A study comparing the black cultivar 'Kokucho' and its purple mutant showed that suppression of DvFNS abolishes the competition between anthocyanidin and flavone synthesis and leads to accumulation of cyanidin and total anthocyanidins that produce a black appearance. Surprisingly, in black cultivars the suppression of DvFNS occurred in a post-transcriptional manner, as determined by small RNA mapping.

The generation of novel species hybrids between garden dahlias and Dahlia macdougallii to increase the gene pool for variety breeding

AbstractTo transfer new traits into the gene pool of garden dahlias (Dahlia variabilis), crosses between garden dahlias (2n = 64) and the epiphytic species Dahlia macdougallii (2n = 32) from the section Epiphytum were conducted. Six hybrid plants were obtained. The hybrid status was verified using three SSR markers. In addition, flow cytometry was performed to determine the genome size of the hybrids and to show that the hybrids were hexaploid as expected from crosses between tetraploids and octoploids. The open pollinated progeny of the hybrids produced four progeny with octoploid genomes. The hybrids exhibited indeterminate vegetative growth and the formation of flowers from axillary buds, similar to the father D. macdougallii. This result is of interest for breeding new varieties of dahlia with traits that are not present in the current gene pool.