Drosera Species Research Articles

Flavonoids occurring in the sticky resin on Roridula dentata and Roridula gorgonias (Roridulaceae)

The leaves of Roridula dentata L. and Roridula gorgonias Planch., two South African plant species, bear numerous glandular hairs, with droplets of sticky liquid at their tips. The plants’ habitus thus largely resembles that of many Drosera species, and also Drosophyllum lusitanicum (L.) Link (Droseraceae)1. The resemblance is further indicated by the fact that Roridula plants trap insects very successfully.

Variations of Naphthoquinone Levels in Micropropaaated Drosera Species In Vitro, under Qreenhouse and Outdoor Growth Conditions

The naphthoquinone levels in clones of the sundew species Drosera communis, D. madagascariensis, D. peltata and D. rotundifolia were determined under in vitro, green house, and outdoor growth conditions. D. rotundifolia revealed a lower naphthoquinone content in vitro which rose upon transfer ex vitro. D. communis and D. madagascariensis exhibited higher levels in vitro which decreased in the greenhouse and further under outdoors conditions. Decreased naphthoquinone levels were found in D. peltata when in vitro cultures were moved to the greenhouse, which increased again when the plants were cultivated outdoors. The results underline that in the cultivation of the medicinally useful carnivorous genus Drosera species-specific differences in the biosynthesis of secondary metabolites under different environmental conditions have to be taken into consideration.

Ecophysiological characterization of carnivorous plant roots: Oxygen fluxes, respiration, and water exudation

Various ecophysiological investigations on carnivorous plants in wet soils are presented. Radial oxygen loss from roots of Droseraceae to an anoxic medium was relatively low 0.02 - 0.07 µmol(O2) m -2 s -1 in the apical zone, while values of about one order of magnitude greater were found in both Sarracenia rubra roots and Genlisea violacea traps. Aerobic respiration rates were in the range of 1.6 - 5.6 µmol kg -1 (f.m.) s -1 for apical root segments of seven carnivorous plant species and 0.4 - 1.1 µmol kg -1 (f.m.) s -1 for Genlisea traps. The rate of anaerobic fermentation in roots of two Drosera species was only 5 - 14 % of the aerobic respiration. Neither 0.2 mM NaN3 nor 0.5 mM KCN influenced respiration rate of roots and traps. In all species, the proportion of cyanide-resistant respiration was high and amounted to 65 - 89 % of the total value. Mean rates of water exudation from excised roots of 12 species ranged between 0.4 - 336 mm 3 kg -1 (f.m.) s -1 with the highest values being found in the Droseraceae. Exudation from roots was insensitive to respiration inhibitors. No significant difference was found between exudation rates from roots growing in situ in anoxic soil and those kept in an aerated aquatic medium. Carnivorous plant roots appear to be physiologically very active and well adapted to endure permanent soil anoxia. Additional key words: aerobic respiration, anaerobic CO2 release, CN - -resistant respiration, Dionea, Drosera, Genlisea, Sarracenia, soil anoxia.

Secondary metabolites inin vitro cultured plants of the genusDrosera

Extracts from plantlets of different species of the genus Drosera, grown as in vitro cultures, were evaluated for the level of phenolic secondary metabolites from the group of naphthoquinones and flavonols. The profiles of natural products in the extracts obtained from different species were monitored by HPLC with UV detection at 260 and 330 nm. On the basis of the data obtained, Drosera binata, the species with the highest amount of plumbagin, was selected for further studies. The most effective method of extraction of quinones was established and the composition of phenolic secondary metabolites in the tissues was determined. For the identification of phenolic compounds, HPLC-UV and HPLC-ESI/MS were applied.

Antimicrobial activity and chemical investigation of Brazilian Drosera

The antimicrobial activity of three different extracts (hexanic, ethyl acetate, methanol) obtained from Brazilian Drosera species (D. communis, D. montana var. montana, D. brevifolia, D. villosa var. graomogolensis, D. villosa var. villosa, Drosera sp. 1, and Drosera sp. 2 ) were tested against Staphylococcus aureus (ATCC 25923), Enterococcus faecium (ATCC23212), Pseudomonas aeruginosa (ATCC27853), Escherichia coli (ATCC11229), Salmonella choleraesuis (ATCC10708), Klebsiella pneumoniae (ATCC13883), and Candida albicans (a human isolate). Better antimicrobial activity was observed with D. communis and D. montana var. montana ethyl acetate extracts. Phytochemical analyses from D. communis, D. montana var. montana and D. brevifolia yielded 5-hydroxy-2-methyl-1,4-naphthoquinone (plumbagin); long chain aliphatic hydrocarbons were isolated from D. communis and from D. villosa var. villosa, a mixture of long chain aliphatic alcohols and carboxylic acids, was isolated from D. communis and 3b-O-acetylaleuritolic acid from D. villosa var. villosa.

Application of rapd in the determination of genetic fidelity in micropropagated Drosera plantlets

Random amplified polymorphic DNA (RAPD) markers were used to verify the clonal fidelity of two micropropagated Drosera species, D. anglica and D. binata, which were regenerated by adventitious budding from leaf explants and shoot tips, respectively. Twenty arbitrary decamers were used to screen 15 randomly selected plantlets of each species. No genetic variation was detected among D. binata regenerants, whereas a 0.08% polymorphism frequency was estimated for D. anglica plantlets. These results indicate that the regeneration of plants through shoot-tip culture is a low-risk method for generating genetic variability, whereas material regenerated through leaf explants requires further verification.

Phylogeny of the sundews, Drosera (Droseraceae), based on chloroplast rbcL and nuclear 18S ribosomal DNA Sequences

The sundew genus Drosera consists of carnivorous plants with active flypaper traps and includes nearly 150 species distributed mainly in Australia, Africa, and South America, with some Northern Hemisphere species. In addition to confused intrageneric classification of Drosera, the intergeneric relationships among the Drosera and two other genera in the Droseraceae with snap traps, Dionaea and Aldrovanda, are problematic. We conducted phylogenetic analyses of DNA sequences of the chloroplast rbcL gene for 59 species of Drosera, covering all sections except one. These analyses revealed that five of 11 sections, including three monotypic sections, are polyphyletic. Combined rbcL and 18S rDNA sequence data were used to infer phylogenetic relationships among Drosera, Dionaea, and Aldrovanda. This analysis revealed that all Drosera species form a clade sister to a clade including Dionaea and Aldrovanda, suggesting that the snap traps of Aldrovanda and Dionaea are homologous despite their morphological differences. MacClade reconstructions indicated that multiple episodes of aneuploidy occurred in a clade that includes mainly Australian species, while the chromosome numbers in the other clades are not as variable. Drosera regia, which is native to South Africa, and most species native to Australia, were clustered basally, suggesting that Drosera originated in Africa or Australia. The rbcL tree indicates that Australian species expanded their distribution to South America and then to Africa. Expansion of distribution to the Northern Hemisphere from the Southern Hemispere occurred in a few different lineages.

Drosera hartmeyorum spec. nov. (Droseraceae), a new sundew in sect. Arachnopus from Northern Australia

Drosera hartmeyerorum, a new species of Drosera (sect. Arachnopus) from Kununurra, northern Western Australia is described.

Observations on a new Drosera species in the Ord River region (Australia)

Observations on a new Drosera species in the Ord River region (Australia)

Naphthoquinone contents of in vitro cultured plants and cell suspensions of Dionaea muscipula and Drosera species

In vitro cultured carnivorous plants were grown on a hormone-free medium. They produced the following naphthoquinones: Dionaea muscipula (plumbagin: 5.3%), Drosera rotundifolia (7-methyljuglone: 0.6%), D. binata (plumbagin: 1.4%), and D. capensis (7-methyljuglone: 0.5%). A red, slow-growing suspension culture of D. muscipula was maintained in a modified McCowns Woody Plant (McC) medium and produced plumbagin (2.59%) after 30 days growth. A suspension culture of D. rotundifolia grew slowly as multicoloured small aggregates only in a modified Murashige and Skoog (MS) medium. No quantifiable amounts of naphthoquinones were produced. Several cell lines of D. capensis were developed. Green aggregates grown in a modified MS medium contained 7-methyljuglone (0.33%) and differentiated into plants when placed onto hormone-free medium. Pink cultures grown in modified McC medium contained 7-methyljuglone (1.24%), while dark red cultures produced ca. 1% in both modified McC and MS media. Though the latter medium was significantly better with regard to biomass production, cells excreted a mucin when cultured in both media (0.21 g dry mucin/g dry cells in McC) and (0.16 g dry mucin/g dry cells in MS). Effects of the presence or absence of light during the growth period of 30 days showed that there was no effect on biomass and only slight effects on mucin production and naphthoquinone contents.

A Chromosome Phylogeny of the Droseraceae by Using CMA-DAPI Fluorescent Banding.

Aldrovanda vesiculosa L., Dionaea muscipula Ellis, 20 species of Drosera L. and Drosophyllum lusitanicum Link. were investigated for a metaphase chromosome analysis by using the sequentially fluorescent CMA and DAPI staining methods. Aldrovanda vesiculosa and the Drosera species showed numerous small-sized chromosomes and some middle-sized chromosomes with no primary constriction. Dionaea muscipula had the middle-sized chromosomes with the localized centromeres and CMA-negative and DAPI-positive pericentric bands. Drosophyllum lusitanicum displayed quite large-sized chromosomes with well-defined localized-centromeres. Computer-aided measurements of metaphase chromosomes stained with CMA and DAPI showed that Aldrovanda vesiculosa and the Drosera species displayed the common features such as localization of CMA-positive and DAPI-negative satellites and non-staining region.

Chromosome Differentiation in Drosera, Subgenus Rorella, Section Rossolis.

The Drosera chromosomes studied were not localized-centromeric but diffused-centromeric. Among the Drosera taxa studied, only D. filiformis (2n=20) had 20 weak CMA-negative orDAPI-positive large bands more than 2.97 μm2 area each at the same site of 20 chromosomes. Thus, its hybrid with D. intermedia (=Drosera × hybrida, 2n=20) had ten CMA weakly-negative orDAPI-positive bands more than 3.00 μm2 each in the same site of ten chromosomes which could be of the gamete of D. filiformis. Drosera petiolaris (2n=14) displayed the meiotic chromosome configuration of six circular bivalents with four distinct chromatids held each other with end-to-end association and two univalents at metaphase I, while D. rotundifolia (2n=20) displayed ten ring-shaped bivalents, that were quite similar to the bivalents of the localized-centromeric chromosomes. These differences in CMA-positive and DAPI-negative bands, IBAS-area, and meiotic chromosome behavior might be correlated with chromosome differentiation and speciation in the species of Drosera of the Northern and the Southern Hemispheres.

The nitrogen supply from soils and insects during growth of the pitcher plants Nepenthes mirabilis, Cephalotus follicularis and Darlingtonia californica.

This study investigated the nitrogen (N) acquisition from soil and insect capture during the growth of three species of pitcher plants, Nepenthes mirabilis, Cephalotus follicularis and Darlingtonia californica. 15N/14N natural abundance ratios (δ15N) of plants and pitchers of different age, non-carnivorous reference plants, and insect prey were used to estimate proportional contributions of insects to the N content of leaves and whole plants. Young Nepenthes leaves (phyllodes) carrying closed pitchers comprised major sinks for N and developed mainly from insect N captured elsewhere on the plant. Their δ15N values of up to 7.2‰ were higher than the average δ15N value of captured insects (mean δ15N value = 5.3‰). In leaves carrying old pitchers that are acting as a N source, the δ15N decreased to 3.0‰ indicating either an increasing contribution of soil N to those plant parts which in fact captured the insects or N gain from N2 fixation by microorganisms which may exist in old pitchers. The δ15N value of N in water collected from old pitchers was 1.2‰ and contained free amino acids. The fraction of insect N in young and old pitchers and their associated leaves decreased from 1.0 to 0.3 mg g-1. This fraction decreased further with the size of the investigated tiller. Nepenthes contained on average 61.5 ± 7.6% (mean ± SD, range 50-71%) insect N based on the N content of a whole tiller. In the absence of suitable non-carnivorous reference plants for Cephalotus, δ15N values were assessed across a developmental sequence from young plants lacking pitchers to large adults with up to 38 pitchers. The data indicated dependence on soil N until 4 pitchers had opened. Beyond that stage, plant size increased with the number of catching pitchers but the fraction of soil N remained high. Large Cephalotus plants were estimated to derive 26 ± 5.9% (mean ± SD of the three largest plants; range: 19-30%) of the N from insects. In Cephalotus we observed an increased δ15N value in sink versus source pitchers of about 1.2‰ on average. Source and sink pitchers of Darlingtonia had a similar δ15N value, but plant N in this species showed δ15N signals closer to that of insect N than in either Cephalotus or Nepenthes. Insect N contributed 76.4 ± 8.4% (range 57-90%) to total pitcher N content. The data suggest complex patterns of partitioning of insect and soil-derived N between source and sink regions in pitcher plants and possibly higher dependence on insect N than recorded elsewhere for Drosera species.

2-methylnaphthazarin 5- O-glucoside from the methanol extracts of in vitro cultures of Drosera species

The methanol extracts of Drosera rotundifolia and D. spathulata obtained by in vitro micropropagation yielded the new pigment 2-methylnaphthazarin (5,8-dihydroxy-2-methyl-1,4-naphthoquinone) 5- O-glucoside, which is an artefact formed from rossoliside (7-methylhydrojuglone 4- O-glucoside) during extraction with methanol.

Self-incompatibility, Seed Abortion and Clonality in the Breeding Systems of Several Western Australian Drosera species (Droseraceae)

Western Australian Drosera L. species include one annualand many tuberous and pygmy perennials. In 20 species or subspecies, 17 taxawere self-incompatible (SI) and three were self-compatible (SC), as assessedby patterns of seed set and pollen tube growth. All SI species were clonal(tubers or gemmae), but two SC species were clonal (gemmae) and one wasannual. Self-pollen tube inhibition confirmed that SI species werepre-zygotically self-sterile. The sites of SI pollen tube inhibition variedfrom early (stigmatic) to late (stylar, placental, ovular), which suggestscontinuing evolution in the expression of the SI response. Self-compatiblespecies showed little inbreeding depression, but SI species showedconsiderable inbreeding depression as measured by seed abortion. In the threespecies tested, open-pollinated capsules were typically more fecund thanhand-pollinated capsules. In D. glanduligera Lehm., thismight represent position effects in an inflorescence that were reflected inthe sampling method. In other species, however, this might also reflectbiparental inbreeding depression in the glasshouse plants. Interspecificcrosses between D. tubaestylis N.Marchant & A.Lowrie(n = 14) and D. rosulataLehm. (n = 13) were slightly successful, with nopollen–pistil incompatibility interaction, but with extensive seedabortion. This is the first report of SI in Droseraceae.

Comparative C-banding and Fluorescent-banding Analysis of Seven Species of Drosera (Droseraceae).

Seven species of Australian Drosera were investigated for a comparative karyotype analysis with different banding schedules, namely Giemsa C-band fluorescent- (CMA- and DAPI-) bandings. Chromosome numbers of D. callistos (2n=28), D. scorpioides (2n=18), D. ericksonea (2n=28), D. pulchella (orange flower) (2n=15), D. scorpioides (2n=16) and D. spilos (2n=18) were reported here for the first time. All the taxa showed asymmetric karyotype in chromosome length. Bimodal karyotypes were observed in D. callistos, D. ericksonea, D. pulchella (pink flower) that perhaps resulted from interspecific hybridization. Sat-chromo-somes were found in D. callistos, D. petiolaris, D. pulchella (pink flower) and D. spilos. The appearance of satellites were strictly stain specific. Three chromosomes of D. pulchella (pink flower) and two chromosomes of D. scorpioides could be identified by their specific response to Giemsa stain. Fluorescent banding revealed that genomic DNA of D. callistos and D. scorpioides rich in AT base composition. A marked differences regarding chromosome numbers, orcein, C-banded and fluorescent banded karyotypes were observed between the two taxa of D. pulchella (pink flower and orange flower), thus needs apeer reinvestigation to elucidate their taxonomic position.

Differential Staining with Orcein, Giemsa, CMA, and DAPI for Comparative Chromosome Study of 12 Species of Australian Drosera (Droseraceae)

Differential stainings with orcein, Giemsa, CMA, and DAPI were compared in 12 species of Western Australian Drosera. Chromosome numbers of D. roseana, D. barbigera, D. leioblasta, D. oreopodion, D. mannii, D. walyunga, D. sewelliae, D. helodes, and D. echinoblasta are reported here for the first time. A marked difference regarding chromosome number was observed in Drosera dichrosepala (2n = 12) from that of the previous report (2n = 18). The karyotypes of the species showed commonly that degree of asymmetry in chromosome length was directly proportional to the mean chromosomal length whereas the number of chromosomes was inversely proportional. Bimodal karyotypes were observed in D. oreopodion, D. walyunga, D. barbigera, and D. echinoblasta, which perhaps resulted from interspecific hybridization of the former two and fragmentation in the latter two. Sat-chromosomes found in D. falconeri, D. sewelliae, D. helodes, and D. echinoblasta responded differently in differential staining. The C and fluorescent bands at the mostly terminal region revealed that maximum C-positive heterochromatin-rich segments, GC-rich segments, and AT-rich segments were accumulated at the ends of Drosera chromosomes. Some chromosomes could be identified by their specific staining property. On the basis of chromosome number and C- and fluorescent-banding pattern, we suggest that D. helodes and D. sewelliae are closely related.

DIFFERENTIAL STAINING WITH ORCEIN, GIEMSA, CMA, AND DAPI FOR COMPARATIVE CHROMOSOME STUDY OF 12 SPECIES OF AUSTRALIAN DROSERA (DROSERACEAE)

Differential stainings with orcein, Giemsa, CMA, and DAPI were compared in 12 species of Western Australian Drosera. Chromosome numbers of D. roseana, D. barbigera, D. leioblasta, D. oreopodion, D. mannii, D. walyunga, D. sewelliae, D. helodes, and D. echinoblasta are reported here for the first time. A marked difference regarding chromosome number was observed in Drosera dichrosepala (2n = 12) from that of the previous report (2n = 18). The karyotypes of the species showed commonly that degree of asymmetry in chromosome length was directly proportional to the mean chromosomal length whereas the number of chromosomes was inversely proportional. Bimodal karyotypes were observed in D. oreopodion, D. walyunga, D. barbigera, and D. echinoblasta, which perhaps resulted from interspecific hybridization of the former two and fragmentation in the latter two. Sat‐chromosomes found in D. falconeri, D. sewelliae, D. helodes, and D. echinoblasta responded differently in differential staining. The C and fluorescent bands at the mostly terminal region revealed that maximum C‐positive heterochromatin‐rich segments, GC‐rich segments, and AT‐rich segments were accumulated at the ends of Drosera chromosomes. Some chromosomes could be identified by their specific staining property. On the basis of chromosome number and C‐ and fluorescent‐banding pattern, we suggest that D. helodes and D. sewelliae are closely related.

Relationship between types of prey captured and growth form in Drosera in southwestern Australia

Abstract Sympatrically growing species of Drosera were examined, including rosette forms, climbers and upright, self‐supporting species, in southwestern Australia, to see whether the height above ground of the capturing leaves influenced the kinds of prey caught. The leaves examined for invertebrate prey remains were all collected at the same time and the results thus represent a snapshot of the prey situation. Although the number of fully opened, active leaves and leaf size among species varied 40‐fold and 22‐fold, respectively, total catch per unit leaf area was relatively constant, regardless of growth form. Growth form was strongly correlated with the kinds of prey caught. Prostrate species caught mainly walking, non‐aerial prey, while self‐supporting and climbing species caught predominantly aerial prey.

Contrasting effects of supplementary feeding of insects or mineral nutrients on the growth and nitrogen and phosphorous economy of pygmy species of Drosera.

Growth responses and accumulation of N and P were studied in two pygmy south-west Australian species of Drosera following supplementary feeding of arthropods (collembolans, Hypogastrura vernalis and fruit flies, Drosophila melanogaster) and/or a balanced mineral nutrient supplement (N as nitrate) via the roots. One feeding experiment used glasshouse-raised germlings from vegetative propagules (gemmae) of the perennial Drosera closterostigma, the other three (two on D. closterostigma and one on the annual D. glanduligera) involved natural populations engaging in natural captures of indigenous prey. All experiments recorded highly significant increases in plant dry matter, N and P (all plant age groups) and in reproductive performance (adult plants only) from artificial feeding of arthropods, but no apparent benefits from minerals alone or additive effects of minerals above that due to insects. Unresponsiveness to mineral nutrients was suggested to relate to inability of the species to use nitrate, while up to three-fold growth and nutrient uptake response to insects indicated that growth of natural populations might be severely limited by inadequate catches of prey. It is concluded that the highly nutrient-poor conditions typical of the habitat of pygmy species of Drosera may have promoted marked specialization towards carnivory and an attendant decline in ability to utilize soil-derived sources of nutrients.