Rhododendron Flower Research Articles

Evolutionary correlation between floral monosymmetry and corolla pigmentation patterns in Rhododendron

Floral symmetry and pigmentation are features of flowers that are believed to be associated due to their shared influence on pollinator behaviour. However, the evolution of such associations has so far not been examined. We analysed variation in Rhododendron flowers, in a phylogenetic context, to test whether the evolution of floral symmetry types and pigment patterns are correlated. Variation in floral symmetry due to variation in corolla form, stamen flexion, stamen arrangement, pistil flexion, as well as corolla pigment patterns was documented in 98 species of Rhododendron. Phylogenetic relations among these species were estimated using maximum likelihood (ML) and Bayesian methods, building on a published molecular dataset of sequences of RNA Polymerase II subunit (RPB2-I). Evolution of the floral traits was studied using phylogenetic correlation tests and ancestral state reconstructions (maximum parsimony, MP and ML methods). Significant correlations were found between corolla pigment pattern and type of floral symmetry at the level of corolla form, stamen flexion or arrangement, and pistil flexion. As expected from their similar roles in enhancing attractability to pollinator, monosymmetric corollas and presence of pigment pattern are correlated; in addition, monosymmetry involving other whorls too shows such a relationship with pigment patterns, and with each other. Multiple evolutionary shifts were detected between monosymmetry and polysymmetry of floral traits in Rhododendron. The relationship between floral monosymmetry attributes and presence of corolla pigment patterns, and additionally, frequent evolutionary shifts in these traits suggest pollinator-mediated selective pressures in Rhododendron.

Cardiovascular collapse due to wild honey Intoxication: A case report

Background: Wild honey has been traditionally been used by indigenous people for its medicinal, aphrodisiac and hallucinogenic properties in Nepal and some other countries. Wild (mad) honey intoxication is one of the rarest presentations to emergency department and is caused by ingestion of wild honey obtained from the nectar of Rhododendron species on the higher altitudes. The cause of mad honey poisoning is the toxin grayanotoxin, found in such wild honey. It can also be caused by consuming the leaves, flowers of Rhododendron from Himalayan belt. Wild honey intoxication has widely been reported from Turkey and the regions around the Black Sea. Some cases have been reported in the few hospitals in Kathmandu and Chitwan. However, such cases have rarely been reported in eastern Nepal. The intoxication might present with mild symptoms of gastrointestinal, cardiovascular and neurological systems or might also present in rare life threatening form with AV block and cardiovascular collapse. Here, we report a case of a seventy three years old man who presented to our emergency department with cardiovascular collapse in the form of severe bradycardia, AV block and hypotension after wild honey consumption.Health Renaissance 2015;13(2): 170-172

Preparation and Evaluation of Functionally Enriched Squash from Rhododendron (Rhododendron arboreum Sm.) Flowers

This study was conducted to prepare functionally enrich squash from Rhododendron (Rhododendron arboreum Sm.) petals. The prepared product was evaluated for various physico-chemical functional properties. The addition of extract effected all the parameters positively. Antioxidant compounds viz. ascorbic acid 33.12±0.03, 14.93±0.09 and 18.80±0.11mg/100g, total anthocyanins 29.67±0.85, 10.88±0.21 and 14.10±0.18mg/100g and total phenols 34.14±0.43, 20.61±0.15 and 21.00±0.11mg/100g were documented in Rhododendron flowers, sugar based Rhododendron squash and honey based Rhododendron squash, respectively. The advancement of storage decreased TSS, total sugars, reducing sugars, acidity, ascorbic acid, total anthocyanins and total phenols but slight increase in pH value of both type of squashes took place. Overall, 30 per cent rhododendron juice and final TSS 45°Brix is recommended to prepare a good quality honey based rhododendron squash.

Evaluation of Antioxidant and Antimicrobial Activity of Rhododendron arboreum Flowers Extract

Ethanolic extract of Rhododendron arboreum flowers was analyzed for antioxidant and antimicrobial activity. Antioxidant activity was determined by DPPH (1, 1-diphenyl-2-picrylhydrazyl) and FRAP (Ferric reducing antioxidant power) assays. The antioxidant activity of flowers extract for DPPH assay was 134.1±2.34 mM TE/g and for FRAP assay was 140.6±2.76 mM TE/g. The antimicrobial activity was measured by agar well diffusion method against six different bacterial species out of which; three were Gram-positive and three were Gram-negative. The minimum inhibitory concentration (MIC) and the minimum bacteriocidal concentration (MBC) were also determined for each pathogen using a 96-well microtiter plate method. The results reported in mg/ml, indicated that all the bacterial strains (Gram-positive and Gram-negative) were effectively inhibited by the ethanolic extract of Rhododendron flowers. E.coli exhibited highest sensitivity to flowers extracts with maximum zone of inhibition (17mm) at extract concentration 50mg/ml and Bacillus cereus and Bacillus subtilis showed minimum inhibition (8mm each) at extract concentration of 25mg/ml. Highest MIC was observed against E.coli (1 mg/ml) and Shigella flexneri (1 mg/ml).

Selection of Reliable Reference Genes for Gene Expression Studies on Rhododendron molle G. Don.

The quantitative real-time polymerase chain reaction (qRT-PCR) approach has become a widely used method to analyze expression patterns of target genes. The selection of an optimal reference gene is a prerequisite for the accurate normalization of gene expression in qRT-PCR. The present study constitutes the first systematic evaluation of potential reference genes in Rhododendron molle G. Don. Eleven candidate reference genes in different tissues and flowers at different developmental stages of R. molle were assessed using the following three software packages: GeNorm, NormFinder, and BestKeeper. The results showed that EF1-α (elongation factor 1-alpha), 18S (18s ribosomal RNA), and RPL3 (ribosomal protein L3) were the most stable reference genes in developing rhododendron flowers and, thus, in all of the tested samples, while tublin (TUB) was the least stable. ACT5 (actin), RPL3, 18S, and EF1-α were found to be the top four choices for different tissues, whereas TUB was not found to favor qRT-PCR normalization in these tissues. Three stable reference genes are recommended for the normalization of qRT-PCR data in R. molle. Furthermore, the expression profiles of RmPSY (phytoene synthase) and RmPDS (phytoene dehydrogenase) were assessed using EF1-α, 18S, ACT5, RPL3, and their combination as internals. Similar trends were found, but these trends varied when the least stable reference gene TUB was used. The results further prove that it is necessary to validate the stability of reference genes prior to their use for normalization under different experimental conditions. This study provides useful information for reliable qRT-PCR data normalization in gene studies of R. molle.

Modelling flowering time of rhododendron

Plant phenology, primarily affected by temperature and photoperiod, is a useful indicator to study the effects of climate change. Even though, it is a proven fact that climate change has affected the phenology of a wide range of species, but degree of impact varies across the species. It is very important to understand the sequence and timing of developmental stages (phenological events) such as bud development and flowering time in response to change in environmental conditions. Along with the identity of being a national flower of Nepal, the beauty of the rhododendron flower welcomes thousands of foreign tourist every year. Non uniformity in flowering time of rhododendron in recent years across the region is commonly expressed by local people and also reported in recent local news. To understand the flowering time behavior of rhododendron a flowering time model was developed in this study. The good agreement between observed and simulated flowering time during the calibration process showed that the developed model has the potential for predicting flowering time of Rhododendron arboreum in response to temperature and photoperiod. Simulation results (Late flowering in higher elevation and early in lower elevation) showed that there exists a linear relationship between altitude and flower onset time of rhododendron in Nepal. In addition, flowering time prediction in response to future climate data showed that phenology of rhododendron is going to shift early as the year advances.

Grayanotoxin-III Detection and Antioxidant Activity of Mad Honey

“Mad honey” is a complex mixture of numerous chemicals produced by honeybees from Rhododendron flowers. Consumption of mad honey leads to diarrhea, perspiration, dizziness, changes in consciousness, syncope, diplopia, as well as blurred vision, hypotension, and bradycardia due to the presence of grayanotoxins (GTXs). Therefore, it is important to detect the level grayanotoxins in mad honey. Besides its toxicity, mad honey also has antioxidant activity. This study was designed to determine the level of grayanotoxin-III toxin and antioxidant activity of ten different mad honey samples collected from the Black Sea region of Turkey. Liquid chromatography-tandem mass spectrometry was used for the quantitation of grayanotoxin-III. Antioxidant activity was evaluated using total phenolic contents, total ferric reducing antioxidant power, scavenging of 2,2-diphenyl-1-picrylhydrazyl and 3-(2-pyridyl)-5, 6-diphenyl-1,2,4-triazine-4’,4’’-disulfonic acid radicals. Quantities of grayanotoxin-III levels ranged from 68.754 to 0.701 µg grayanotoxin-III/g honey. Mad honey MH7 from Artvin/Hopa had the highest grayanotoxin-III level. Although there were varying levels of grayanotoxin-III, mad honey samples were outstanding in terms of antioxidant activity. MH3 had the highest antioxidant potential. Although toxicity effect comprises, a metered dose of mad honey might also be explored as a potential source in clinical trials due to high bioactivity levels.

Ice nucleation activity in various tissues of Rhododendron flower buds: their relevance to extraorgan freezing.

Wintering flower buds of cold hardy Rhododendron japonicum cooled slowly to subfreezing temperatures are known to undergo extraorgan freezing, whose mechanisms remain obscure. We revisited this material to demonstrate why bud scales freeze first in spite of their lower water content, why florets remain deeply supercooled and how seasonal adaptive responses occur in regard to extraorgan freezing in flower buds. We determined ice nucleation activity (INA) of various flower bud tissues using a test tube-based assay. Irrespective of collection sites, outer and inner bud scales that function as ice sinks in extraorgan freezing had high INA levels whilst florets that remain supercooled and act as a water source lacked INA. The INA level of bud scales was not high in late August when flower bud formation was ending, but increased to reach the highest level in late October just before the first autumnal freeze. The results support the following hypothesis: the high INA in bud scales functions as the subfreezing sensor, ensuring the primary freezing in bud scales at warmer subzero temperatures, which likely allows the migration of floret water to the bud scales and accumulation of icicles within the bud scales. The low INA in the florets helps them remain unfrozen by deep supercooling. The INA in the bud scales was resistant to grinding and autoclaving at 121∘C for 15 min, implying the intrinsic nature of the INA rather than of microbial origin, whilst the INA in stem bark was autoclaving-labile. Anti-nucleation activity (ANA) was implicated in the leachate of autoclaved bud scales, which suppresses the INA at millimolar levels of concentration and likely differs from the colligative effects of the solutes. The tissue INA levels likely contribute to the establishment of freezing behaviors by ensuring the order of freezing in the tissues: from the primary freeze to the last tissue remaining unfrozen.

Effect of rhododendron flower juice on the bioavailability of amlodipine in rats

The aim of the study was to determine the effect of rhododendron flower juice on the bioavailability of Amlodipine in rats. This study was carried out in rats as a parallel design study. After the analysis of blood samples, it has been concluded that a component (s) of rhododendron flower juice inhibits the CYP3A4 mediated metabolism of Amlodipine. AUC was determined with the help of Trapezoidal rule. C max and T max were determined from the area under the plasma concentration-time curve. Statistical analysis was performed on the data obtained from both the group of rats. One way Analysis of Variance (ANOVA) from which Tukey-Kramer Multiple Comparisons Test was applied to the data obtained. This test compared all the parameters such as AUC, C max and T max without flower juice and after giving flower juice and the standard deviation of AUC of amlodipine with and without juice was found to be 14.25 and 10.44 respectively. AUC of the amlodipine after giving rhododendron flower juice to rats was significantly increased in comparison to the control group. The Overall result indicates that the oral bioavailability of amlodipine after giving rhododendron flower juice was increased as compared to the amlodipine with water.

The Honey, The Poison, The Weapon

The Honey, The Poison, The Weapon

Biological activities and chemical composition of three honeys of different types from Anatolia

In this study, we investigated and compared some chemical properties and in vitro biological activities of three different types of Turkish honey. The first two honey samples were monofloral from chestnut and rhododendron flowers, collected from the east Black Sea region, and the third sample was the heterofloral form of astragalus ( Astragalus microcephalus Willd.), thyme ( Thymus vulgaris) and other several mountain flowers, collected from Erzincan in Eastern Anatolia. The chemical properties of the honey samples, such as total moisture, ash, total protein, sucrose, invert sugar, diastase activity, hydroxymethylfurfural content and acidity, were determined. Total phenolics, superoxide radical- and peroxynitrite-scavenging activities, and ferric reducing/antioxidant power measurements were used as antioxidant capacity determinants with ±-catechin, butylated hydroxytoluene, ascorbic acid, and trolox ® used as reference. The antimicrobial activity was studied by the agar diffusion method, using eight bacteria and two yeasts. The mineral contents were also determined by an AAS method. The chestnut flower honey had the highest phenolic content, superoxide radical-scavenging activity and reducing power, while the heterofloral honey sample exhibited the highest peroxynitrite-scavenging activity. The antioxidant activities were also found to be related to the sample concentrations. The mineral content of the chestnut honey was much higher than the others. The samples showed moderate antimicrobial activity against some microorganisms, especially Helicobacter pylori ATCC 49503, Staphylococcus aureus ATCC 25923, Bacillus subtilis ATCC 6633, Candida tropicalis ATCC 13803 and Candida albicans ATCC 10231. The honey samples studied proved to be a good source of antioxidants and antimicrobial agents that might serve to protect health and fight against several diseases.

Supercooling Ability, Water Content and Hardiness of Rhododendron Flower Buds during Cold Acclimation and Deacclimation

Supercooling Ability, Water Content and Hardiness of Rhododendron Flower Buds during Cold Acclimation and Deacclimation

Supercooling ability of Rhododendron flower buds in relation to cooling rate and cold hardiness

Supercooling ability of Rhododendron flower buds in relation to cooling rate and cold hardiness

Supercooling ability of Rhododendron flower buds in relation to cooling rate and cold hardiness

Supercooling ability of Rhododendron flower buds in relation to cooling rate and cold hardiness

The Rest Period ofRhododendronFlower Buds

Rhododendron flower development occurs in three easily defined stages: a pre-rest stage, during which petal growth is mainly by cell elongation; an indeterminate rest period; and an after-rest stage, that begins when the flowers resume growth and ends at anthesis. Early in the pre-rest stage of development, protein bodies and amyloplasts accumulate in the petals. The epidermal cells accumulate only protein bodies and the mesophyll cells accumulate amyloplasts that have a few small protein bodies around the periphery. The subepidermal cells and the cells around the vascular bundles accumulate both large protein bodies and amyloplasts. During the rest period there is a cessation of cell elongation and the reserve protein bodies and amyloplasts remain intact. The protein bodies in all of the cells including those around the amyloplasts are proteolized early in the after-rest stage of development. Digestion of the starch granules occurs when the petals are about one-half their final size. Epidermal-cell expansion during after-rest is relatively uniform; the walls between adjacent epidermal cells remain attached to each other. The mesophyll cells elongate irregularly and the walls of adjacent cells separate giving rise to large intercellular spaces. At anthesis the petal cells consist of a cell wall, a parietal cytoplasm, and a large central vacuole.

The Rest Period ofRhododendronFlower Buds: II. STUDIES ON THE REST PERIOD IN TISSUE 3IN SITU

Shortly after the onset of rest in Rhododendron flower buds, the buds were transferred to a tissue-culture medium. The results reported here show that the rest period in culture was identical to the rest period of buds in situ. In both environments the duration of rest and the frequnency distribution of elongation of the buds were the same. Histograms of bud development against time were bimodal, with about 20 per cent of the buds elongating during the second peak. In culture, the rest period was not affected by changes in pH, temperature, or the addition of nutrient salts. The results further show that the duration of the rest period of each bud was independent of the time of the onset of rest. Buds that were supplied with either indol-3yl-acetic acid or gibberellic acid in culture or in situ remained in rest. Only a low temperature treatment had a rest-breaking influence.

Occurrence of flavonol 5-methyl ethers in higher plants and their systematic significance

Kaempferol 5-methyl ether has been identified for the first time in plants. It was found in leaves or flowers of Rhododendron spp., of Erica, Kalmiopsis and Rhodothamnus (all Ericaceae) and in Tetracera (Dilleniaceae). Surveys of the Ericaceae have also revealed that quercetin 5-methyl ether (azaleatin) is common as a leaf as well as a flower constituent; it is widespread in Rhododendron and also occurs in seven other genera. It is accompanied by the 3,5-dimethyl ether, caryatin, in leaves of some of these plants; in Rhododendron, caryatin is confined to species of the subgenus Eurhododendron. The presence of azaleatin in Tetracera (Dilleniaceae) has been confirmed. Together with earlier results, these findings show that flavonol 5-methyl ethers occur in fifteen genera from six plant families. Their systematic value is mainly confined to their distribution within these families but their presence in only woody families may have phyletic significance.

Plant polyphenols: 5. Occurrence of azalein and related pigments in flowers of Plumbago and Rhododendron species

Azalein (5-methylquercetin 3-rhamnoside) and a new anthocyanidin, present as the 3-rhamnoside, have been isolated from Plumbago capensis. The 3-rhamnosides of pelargonidin, cyanidin, delphinidin and kampferol have been found in Plumbago rosea. Azalein has also been found in 44 out of 83 Rhododendron species examined. The 3-galactoside and 3-arabinoside of quercetin and the 3-arabinoside of cyanidin have been found for the first time in Rhododendron flowers.

マルハナバチ類の訪花性

Flower-visiting habits of 3 species of the genus Bombus were examined during from spring to autumn of 1951-1959. Nesting or flower-visiting activities were observed till early summer in B. ardens, and till autumn in B. ignitus and B. diversus, respectively. The number of flower-visiting workers became maximum during the periods of April-May in B. ardens, and June in B. diversus and B. ignitus.The workers of B. diversus visited flowers of 76 species belonging to 31 families. Particularly, the flowers of Leguminosae, Labiatae and Liliaceae were visited predominantly by this workers. Moreover, they preferred mostly the flowers of Cirsium japonicum, Rosa multiflora, Vicia unijuga, Prunella vulgaris, Trifolium repens, Salvia chinensis, Impatiens textori, Pertya ovata, Astragalus sinicus and Styrax japonica.The workers of B. ignitus visited flowers of 24 species belonging to 14 families. The flowers of Leguminosae were visited predominantly by them. These workers preferred mostly the flowers of Trifolium pratense and Vicia unijuga.The workers of B. ardens visited flowers of 32 species of 18 families, especially, the flowers of Leguminosae, Rosaceae and Caprifoliaceae predominantly. And these workers rather preferred the flowers of Rosa multiflora, Rhododendron sp., Styrax japonica, Rubus parvifolius and Diospyros Kaki.

Crystalline chemical components of the flowers ofRhododendron nilagiricum Zenk

The flowers ofRhododendron nilagiricum Zenk. have been examined for their crystalline components by extraction with organic solvents and fractionation along usual lines. Quercitrin and ursolic acid could be isolated as such and quercetin after hydrolysis of one of the crude fractions.