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Blue flowers, which are rare, have long been a focus for researchers engaged in colored flower breeding. In this study, Plumbago auriculata, a plant with blue flowers, and its white flower forma Plumbago auriculata f. alba were used as research materials. Flower color quantification, environmental scanning electron microscopy (ESEM) observation of petal epidermal cells, and determination of the cell sap pH were carried out; moreover, metabolomic analysis was used to analyze the flavonoid metabolites of both types of petals. The results showed that the flower color of P. auriculata was bluish violet, and there was no significant difference in the epidermal cell distribution of the white and blue petals. The key substance that determined the bluish violet flower color was cyanidin-3-O-(6″-p-coumaroylglucoside) (Cy3-pC·G). Compared to the white petal cells, the blue petal cells exhibited up to 40 upregulated flavonoid compounds that were copigments. Together with the significantly increased pH (5.92 ± 0.12) of the petal cell sap, these copigments affected the color presentation of Cy3-pC·G, causing the final petal color of P. auriculata to be bluish violet. The results of this study indicate that cyanidin is an important anthocyanidin in blue flowers, which provides new insights into the breeding of blue flowers.

Zinc oxide nanoparticles (ZnO NPs) were synthesized by using an alcoholic extract of the flowering aerial parts of Plumbago auriculata Lam. Dynamic Light Scattering (DLS) revealed that the average size of synthesized ZnO NPs was 10.58 ± 3.350 nm and the zeta potential was −19.6 mV. Transmission electron microscopy (TEM) revealed that the particle size was in the range from 5.08 to 6.56 nm. X-ray diffraction (XRD) analysis verified the existence of pure hexagonal shaped crystals of ZnO nanoparticles with an average size of 35.34 nm in the sample, which is similar to the particle size analysis acquired by scanning electron microscopy (SEM) (38.29 ± 6.88 nm). HPLC analysis of the phenolic ingredients present in the plant extract showed that gallic acid, chlorogenic acid, and catechin were found as major compounds at concentrations of 1720.26, 1600.42, and 840.20 µg/g, respectively. Furthermore, the inhibitory effects of ZnO NPs and the plant extract against avian metapneumovirus (aMPV) subtype B were also investigated. This assessment revealed that the uncalcinated form of Nano-ZnO mediated by P. auriculata Lam. extract possessed a significant antiviral activity with 50% cytotoxic concentration (CC50) and 50% inhibition concentration (IC50) of 52.48 ± 1.57 and 42.67 ± 4.08 µg/mL, respectively, while the inhibition percentage (IP) was 99% and the selectivity index (SI) was 1.23.

Heteromorphic self-incompatibility (HetSI), which is regulated by sporophytes, occurs in some species as a strategy to promote cross-pollination. This research aimed to reveal metabolic changes occurring in HetSI. We used fluorescence microscopy as a tool to compare growth behavior in self-incompatible (SI) and self-compatible (SC) pollination in both pin and thrum flowers of Plumbago auriculata and to identify the ideal timepoint for sample collection for subsequent experiments. We also employed scanning electron microscopy (SEM) to evaluate intermorph structural differences in the pollen grains and stigmas in relation to HetSI. Importantly, UPLC-MS/MS was applied in this study to identify metabolites, compare metabolic differences between pin and thrum styles and monitor metabolic changes in SC and SI pollinations in the two types of flowers. The metabolites mainly included amino acids/peptides, flavonoids, glycosides/sugars, phenols, other organic acids, fatty acids (derivatives)/lipids, amines, aldehydes, alkaloids, alcohols and other compounds. Surprisingly, energy-related nutrients such as amino acids/peptides and tricarboxylic acid cycle-related metabolites were found at higher levels in SI pollinations than in SC pollinations. This result indicates that physiological changes in pollen-stigma interactions differ in pin and thrum styles and SC and SI pollinations and that energy deficiency is not one of the reasons for HetSI.

Plumbago auriculata Lam. is an ornamental plant native to South Africa and widely cultivated in China, but the cultivated plants are dominated by a single variety. The development of new varieties is of great commercial interest, and genetic diversity is the foundation of breeding programs. In this study, 85 progenies were obtained by crosses between Plumbago auriculata and Plumbago auriculata f. alba. The genetic diversity of these hybrids was evaluated using horticultural traits and ISSR and SRAP markers. Of the 25 horticultural traits evaluated, the largest variation was found in the beginning of the blooming period, and sepal length was the least variable trait. Correlation analysis showed that the wider the plant, the greater the number of inflorescences and the earlier the flowering. Seven factors explained 65.171% of the total variance; the first factor was leaf morphology, and the second factor was flower morphology. The genetic diversity of the 85 progenies was analyzed using seven pairs of SRAP primers and eight ISSR primers. The average number of effective alleles for 85 hybrids was 1.638, and the average Shannon index value was 0.507. The Nei genetic similarity coefficient indicated that the similarity between WLBS and WSBL was the highest, while that between BLWS and BSWL was the lowest. Analysis of molecular variance (AMOVA) indicated that the main variation was within populations. Cluster analysis based on horticultural traits and molecular markers divided all progenies into seven and five groups, respectively, and there were obvious differences between the two clusters. In this study, we created intermediate materials for future breeding, taking the first step in the cross-breeding of P. auriculata.

This work reports the synthesis of silver nanoparticles (AgNPs) using aqueous extract of Plumbago auriculata, and evaluates their antibacterial and larvicidal activities. The synthesized silver nanoparticles were characterized by various spectroscopy techniques, such as FTIR, XRD, TEM, EDX, Zeta potential, and DLS. The synthesized AgNPs exhibited significant antibacterial activity against Gram-positive and Gram-negative bacteria, such as Bacillus subtilis, Staphylococcus aureus, Escherichia coli, and Klebsiella pneumoniae. Furthermore, synthesized nanoparticles inhibited the fourth instars larvae of Aedes aegypti and Culex quinquefasciatus at the concentration of 45.1 and 41.1 &micro, g/mL respectively. Results of dose-dependent studies showed that synthesized nanoparticles were also effective at low concentrations. Molecular docking studies performed with the salivary protein and odorant-binding protein of Aedes aegypti and Culex quinquefasciatus demonstrated that the naphthoquinone compound plumbagin exhibited reliable binding affinity towards the two enzymes. The findings thus reveal that the plant extract and its nanoparticles can be a better alternative to available chemicals to control mosquitos.

With its rare and naturally blue corolla, Plumbago auriculata Lam. has received attention and been introduced and planted worldwide. However, it is sensitive to low temperatures. Continuous low temperatures cause the stagnation of plant growth and the disappearance of ornamental traits. Currently, there is no report on the response of P. auriculata to low temperature. In this study, the chlorophyll fluorescence parameters of P. auriculata leaves were analysed after 10 days of low-temperature stress, and 943 differentially expressed genes were identified via high-throughput RNA sequencing. P. auriculata copes with low-temperature stress by changing the pathways of sugar metabolism, glutathione metabolism and lipid metabolism; however, the decrease in the assimilation level caused by damage to the photoreaction system is an important reason for plant growth stagnation. In addition, we identified 47 differentially expressed transcription factors, including the upregulated MYBS3 transcription factor, which is involved in the MYBS3-dependent pathway that is distinct from the DREB/CBF pathway. Our data reveal the cause of P. auriculata stagnation at low temperatures and provide valuable information for further studies on cold-response mechanisms and the genetic improvement of cold tolerance in P. auriculata.

Plumbago auriculata (Plumbaginaceae) is a perennial ornamental shrub with many therapeutic values and native to South Africa (Saji & Antony, 2015). Several groups of phytoplasma have been reported to infect ornamental and…

In this study, the chromosome karyotype of Plumbago auriculata was analyzed by using a chromosome mounting technique with the primary root tip of seed germination. The aim was to find out the most suitable method for Plumbago auriculata by comparing the effect of different pre-treatment and dissociation time on chromosome. The results showed that the best pretreatment was 0.05% colchicine solution under 0℃ - 4℃ or 2 h and then 1 mol/L HCL under 60℃ water for 6 min. Karyotype analysis of Plumbago auriculata showed that the chromosome number was 12 and the karyotype formula was 2n = 2x = 12 = 8 m (4 sat) + 4 sm. The karyotype belonged to 2B and the karyotype asymmetry coefficient was 59.41%. The absolute average length of chromosome was 0.40 μm and the average arm ratio was 1.54. The chromosome of Plumbago auriculata belonged to minichromosome, including a couple of SAT-chromosomes.

With the explants of young nodals and leaves of Plumbago auriculata, we studied multiple shoots induction and plant regeneration in the medium with different PGR proportions. The results showed the nodals of Plumbago auriculata could be used as the explant to induce multiple shoots. After culturing young nodals for 30 d, optimum single shoot formation was achieved on MS medium supplemented with 0.3 mg/L 6-BA and the induction rate was 70.79%. After being transferred to the medium containing 1.0 mg/L 6-BA, 1.0 mg/L NAA and 0.2 mg/L IAA for 1 - 2 generation, single shoot was induced to form multiple shoots with the multiplication rate was 506.45%. After multiple shoots grew to 3 cm high, the multiple shoots were cut into single shoots and transferred onto half-strength MS medium supplemented with 0.5 mg/L NAA and the rooted rate was 94.33%. Finally the intact plants were obtained.

A natural compound plumbagin (5-hydroxy-2-methyl-1,4-naphthoquinone) was isolated from the leaves of Plumbago auriculata and found to inhibit the enzyme, 8-amino-7-oxononanoate synthase (AONS, also known as 7-keto-8-aminopelargonate synthase, KAPAS) an IC 50 of 2.1 μM in vitro . Biotin supplement significantly rescued the plant injury caused by the plumbagin treatment, and this result confirmed the target site, AONS. Foliar application of 1000 ∼ 2000 μg/mL plumbagin in a greenhouse condition showed lethal activity against eight species of weeds, containing three grass species of Sorghum bicolor , Echinochloa crus-galli , Digitaria sanguinalis and five broad leaf species of Solanum nigrum , Aeschynomene indica , Abutilon avicennae , Xanthium strumarium , Calystegia japonica . Field trial of foliar application with plumbagin 2000 μg/mL have successfully controlled 10 ∼ 15 leaf-stages and 2 ∼ 3 m vine lengths of Sicyos angulatus at the natural habitats around riparian zone in the Nam-Han River in Korea. Visual symptom of desiccation might be induced by the physiological cellular leakage which was significantly dose dependent on the plumbagin treatment regardless of light.

Roots that form from non-root tissues (adventitious roots) are crucial for cutting propagation in the forestry and horticulture industries. Strigolactone has been demonstrated to be an important regulator of these roots in both Arabidopsis and pea using strigolactone deficient mutants and exogenous hormone applications. Strigolactones are produced from a carotenoid precursor which can be blocked using the widely available but broad terpenoid biosynthesis blocker, fluridone. We demonstrate here that fluridone can be used to promote adventitious rooting in the model species Pisum sativum (pea). In addition, in the garden species Plumbago auriculata and Jasminium polyanthum fluridone was equally as successful at promoting roots as a commercial rooting compound containing NAA and IBA. Our findings demonstrate that inhibition of strigolactone signaling has the potential to be used to improve adventitious rooting in commercially relevant species.

Males of the predaceous stink bug Podisus maculiventris (Say) (Heteroptera: Pentatomidae: Asopinae) emit low frequency tremulatory signals. Laser vibrometry was used to record and analyze naturally emitted signals, focusing on variation in signal velocity and frequency during transmission through plants (Phaseolus vulgaris L. and Plumbago auriculata Lam.) as a function of distance from the vibrational source. Signal velocity varied individually between 2 and 15 mm/s recorded on a plant close to the calling male and decreased by 0.3 to 1.5 dB/cm on bean and 0.3 to 0.9 dB/cm on plumbago. The dominant frequency of signals was variable at frequencies below 50 Hz. On bean frequencies centered around 10 Hz or 20 Hz were dominant for signals recorded at the source. Transmission through bean resulted in an increase in the 20 Hz peak relative to other frequencies in the signal. Variation of the dominant frequencies of signals transmitted through plumbago stems were more predictable, showing typical changes in amplitude relative to the distance from the source. The regular variation of the dominant frequency along the stem with linear increase of signal velocity at decreasing distance from the source may provide plant-dwelling insects with information about the distance to the calling individual.

Plants with hermaphrodite flowers risk conflict between male and female sexual function due to close proximity of sexual organs. Heterostyly, a genetic floral polymorphism characterized mainly by reciprocal herkogamy, may reduce this sexual conflict by increasing the precision of pollen transfer between morphs. This sexual organ reciprocity is often associated with various ancillary characters and a heteromorphic incompatibility system. Here we describe the morphometrics associated with heterostyly and ancillary characters in Plumbago auriculata. Using controlled pollination experiments, we show that this species has a heteromorphic incompatibility system. We also document the fauna of long-proboscid fly and butterfly pollinators in a P. auriculata population in KwaZulu-Natal, South Africa. © 2009 SAAB. Published by Elsevier B.V. All rights reserved.

Dichloromethane and 90% methanol extracts from 51 South African medicinal plants were evaluated for potential genotoxic effects using the bacterial Ames and VITOTOX® tests with and without metabolic activation. Dichloromethane extracts from bulbs of Crinum macowanii showed mutagenicity in strain TA98 with and without metabolic activation, whereas extracts from leaves of Chaetacme aristata and foliage of Plumbago auriculata showed mutagenicity and/or toxicity. Extracts from the leaves of Catharanthus roseus and twigs of Combretum mkhzense were mutagenic with metabolic activation only. The only 90% methanol extracts that were mutagenic in strain TA98 were from the leaves of C. roseus and Ziziphus mucronata in the presence of metabolic activation. No genotoxic effects were found in strain TA100 or in the VITOTOX® test.

The genus Plumbago belongs to the family Plumbaginaceae, order Plumbaginales. Comparative chemical profile of P. scandens (native) and P. auriculata (cultivated) was obtained by normal and reversed-phase high performance liquid chromatography with photodiode array detector. Comparison of the ultraviolet espectra and the retention times for the compounds allowed to find similar metabolic patterns in roots, stems and leaves. Four flavonoids, one phenolic acid or derivative and the naphtoquinone plumbagin were comparatively identified to standards.

Three locally available Plumbago species (Plumbago auriculata, Plumbago rosea and Plumbago zeylanica) have been quantitatively screened for the bioactive marker plumbagin by high performance thin layer chromatography. In general, the root parts were found to be the rich sources for plumbagin. Most significantly, P. rosea was found to accumulate maximum plumbagin in the roots. In contrast, P. auriculata and P. zeylanica are high yielding species for the leaf and stem parts, respectively. Studies have also been extended to evaluate some P. rosea samples collected from southern India and a traditional medicine, Chitrakadi vati, which contains P. zeylanica as the major constituents.

We characterized the behavior of plastid (pt) and mitochondrial (mt) nucleoids during male gametogenesis in Plumbago auriculata in three dimensions. The behavior of pt-nucleoids and mt-nucleoids differed throughout male gametogenesis. Pt-nucleoids were distributed in a characteristic manner in three stages: in the early microspore, pt-nucleoids assemble around cell nucleus; in the mid-generative cell, pt-nucleoids gather at the internal side of the pollen; in the late-generative cell, pt-nucleoids aggregation turns its pole to the external side of the pollen. We also studied organelle nucleoids in the egg and the central cell by a method in which semi-thick sections of resin-embedded anthers and ovaries were observed by confocal laser scanning microscopy. The number of pt-nucleoids in the sperm cell did not differ significantly from that in the egg. These results suggest that the behavior of DNA-containing organelles is regulated strictly during male gametogenesis in P. auriculata, and that a biparental inheritance of plastids in the Plumbago embryo is more favored than was previously thought.

The main aim of this study was to develop a rapid and cheap bioassay to identify germination inhibitory compounds directly from plant crude extracts. Extracts of Plumbago auriculata and Carya illinoinensis as well as their previously identified allelopathic compounds, plumbagin and juglone, respectively, were developed on TLC plates. The plates were covered with a thin layer of agar (2–4 mm) and Lactuca sativa (lettuce) and Arabidopsis thaliana seeds placed onto it. After incubation of the plates for three days complete germination inhibition correlating to specific compounds in the extract was clearly visible. Plumbagin and juglone inhibited the growth of the seeds completely while a second compound in the P. auriculata extract also showed inhibition. This compound was identified through chemical synthesis as plumbagin epoxide. This is the first report of its presence in P. auriculata . By using this bioassay on TLC, plant extracts can be tested cheaply and rapidly and the compounds responsible for germination inhibition be identified.

To examine whether cytoplasmic rRNA are present at high density in the cytoplasm of generative and sperm cells (generative/sperm cells) in pollen grains of various plant species, in situ hybridization of 18S/25S rRNA was performed in thin sections of samples embedded in Technovit 7100 resin. The five plant species studied were Lilium longiflorum, Pharbitis nil, Silene latifolia, Pelargonium zonale and Plumbago auriculata. The timing and mode of pollen mitosis II (PM II) and the distribution of organelle nucleoids in generative/sperm cells differ in these species. In situ hybridization revealed that the density of rRNA was the same as or higher in generative/sperm cells than in vegetative cells, suggesting that the presence of rRNA in the generative/sperm cells at high density may be a general characteristic of mature pollen grains of various plant species.

Most synthetic herbicides are used for controlling troublesome weed species in modern agriculture all over the world. However, consecutive use of the same herbicide brings about resistant weed problems and many countries are restricting repeated treatment in agricultural lands [1]. For these and environmental reasons, new herbicide discovery and subsequent registration is very challenging. Recently, evaluating natural products of ani‐ mals, plants, microorganisms and minerals for developing environmental friendly herbi‐ cides has increased [2]. Several compounds have been developed or in development as natural herbicides such as bialaphos [3], methoxyhygromycin (MHM) [4], and pelargonic acid [5]. Essential oils such as clove oil and cinnamon oil also contain allelochemicals that control a broad spectrum of weeds and can be used as natural herbicide source [6,7]. Plumbagin isolated from Drosophyllum lusitanicum and Plumbago auriculata inhibited the seed germination of lettuce and wheat [8,9]. Several classes of natural compounds in‐ cluding triketones, benzoquinones, naphthoquinones and anthraquinones have been re‐ ported as hydroxyphenylpyruvate dioxygenase (HPPD) inhibitors and hence the novel classes of HPPD inhibitors could be developed based on their structural backbones [10].

Phytochemical investigations of blue plumbago ( Plumbago auriculata Poir. syn. Plumbago capensis Thunb.) flowers have led to the isolation of six new anthocyanins based on three new anthocyanidins with 5,7-dimethoxylated A-rings. Their structures were identified by 2D nuclear magnetic resonance and high-resolution mass spectrometry as the 3-O-β-galactopyranosides (1,2,4) and 3-O-α-rhamnopyranosides (3,5,6) of 5,7-dimethyldelphinidin, 5,7-dimethylpetunidin, and 5,7-dimethylmalvidin. Identification of 1-6 implies new structures for the previously reported anthocyanidins pulchellidin, europinidin, and capensinidin to be 5,7-dimethoxy-3,3',4',5'-tetrahydroxyflavylium, 5,7,3'-trimethoxy-3,4',5'-trihydroxyflavylium, and 5,7,3',5'-tetramethoxy-3,4'-dihydroxyflavylium cations, respectively. The anthocyanins (0.4 mg/g flowers) were accompanied by the dihydroflavonol taxifolin 3'-O-β-glucopyranoside (1.4 mg/g) and the flavonols 5-methylquercetin 3-O-α-rhamnopyranoside (8.8 mg/g) and 5-methylquercetin (0.4 mg/g). The anthocyanins 1-6 are the first reported natural anthocyanins with no free hydroxyl groups in their 5- and 7-positions on their A-rings. They have thus no possibility of forming the tautomeric quinonoidal bases (anhydrobases), which are related to the free hydroxyl groups in the 5- and 7-positions of previously reported anthocyanins. The genes behind the 5,7-dimethoxylated anthocyanins might be useful for making anthocyanins with special properties (colors, etc.).

The rapid clonal multiplication of two species of South African Drosera is described. Levels of plumbagin, (5-hydroxy-2-methyl-1,4-naphthoquinone) from in vivo and in vitro grown plants are compared to those present in Plumbago roots. P. auriculata Lam. roots contained more than twice as much plumbagin as in vivo grown D. capensis L. plants which in turn contained more than twice as much as comparable plants of D. natalensis Diels. It is concluded that the extraction of plumbagin from Drosera plants is not commercially feasible.

A study was conducted to evaluate establishment of root-bound vs. nonroot-bound container-grown Plumbago auriculata Lam. in a landscape. A total of 144 plants were transplanted from #1 containers in a rain-out shelter at Mid-Florida Research and Education Center, Apopka, Fla., in June 2004. The field soil type was amended with composted yard waste. The three treatment types used for the study were: 1) root-bound plants; 2) root-bound plants with a vertical slice made through the root ball at a 90° angle; and 3) nonroot-bound plants. To evaluate the effect of these three treatments during the course of establishment period, harvesting was done once every 2 weeks. Data on growth indices (height × width × width), shoot dry weight, root dry weight, and length of the longest root were recorded. The experimental design was a completely randomized design consisting of three treatments, 12 harvest dates (days after planting), and four replicates per harvest date. Plants were maintained according to the best management practices recommended by the UF/IFAS, and were irrigated once a day using microirrigation. Experimental data were analyzed for significance of correlation among variables using SAS version 9.1. Results of the correlation and regression analysis indicated that the increase in the shoot dry weights (g), root dry weights (g), growth indices (m3), and root: shoot ratio had significant relationship with the harvest dates. Correlation among harvest dates and shoot dry weight, root dry weight, or growth indices was found to be positive. However, results of the study indicated that as the number of days after planting increased, the root to shoot ratio decreased.

Historically, plants have proven their value as a source of phytochemicals with therapeutic potentials and recently they play an important role in the discovery of novel drugs. The current study aimed to investigate new antiobesity drugs from Plumbago europaea and Plumbago auriculata through the inhibition of the adsorption of dietary lipids. In vitro porcine pancreatic lipase inhibitory tests were conducted with weight reduction property as well as this study aimed to explore the antioxidant potential and to estimate total phenolic, flavonoid, and tannin contents in both of the studied species. Antioxidant capacity was evaluated using ferric reducing antioxidant power and DPPH assays, and porcine pancreatic lipase inhibitory tests were conducted using the UV spectrophotometric method, while total flavonoid, phenol, and tannin contents were estimated using standard phytochemical analytical methods. Antioxidant potential and total flavonoid, phenol, and tannin contents of P. europaea were significantly higher than those of P. auriculata, and both of the studied species have potential antiobesity activity in comparison with orlistat. Results of the present study show that both of the studied Plumbago species consist of bioactive compounds that can act as lipase inhibitors and therefore can be useful for the development of functional foods against obesity. It can also be used as a source of lead compounds for designing new antiobesity drugs. Further isolation, identification, and characterization of phyto-active compounds responsible for antiobesity action are required to evaluate the full therapeutic potentials of these plants.