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This study determined the allelopathic potential of Rhododendron arboreum Sm. on the germination and growth of 4-crops (Eleusine coracana (L.) Gaertn., Echinochloa frumentacea Link, Glycine max (L.) Merr. and Vigna umbellata (Thunb.) Ohwi & H. Ohashi) of Garhwal Himalaya. Both in-vitro and pot culture bioassays were conducted to evaluate the impact of leaf and bark aqueous extracts (2 %, 5 % and 10 %) on germination (%), mean germination time (MGT), germination index (GI), and root and shoot growth of test crops. The crop species had significant and variable impacts on germination and growth parameters in both in-vitro and pot-culture bioassays. In contrast, extract types greatly influenced these parameters under in-vitro conditions than in pot culture. Under in-vitro conditions, leaf extracts significantly inhibited the germination and seedling development of Eleusine coracana and Glycine max, with reductions in radicle and plumule length. Bark extracts exhibited both inhibitory as well as stimulatory effect on germination and growth. In pot culture, both extract types elicited variable germination responses in all crops. Stimulatory effects on root and shoot growth were observed in V. umbellata and E. frumentacea. E. coracana showed inhibition in shoot growth but stimulation in root growth, while in G. max root and shoot development was inhibited. The allelopathic effects of R. arboreum extracts both inhibited and stimulated crop growth depending on extract concentration and crop type. R. arboreum longer-term interactions enhanced the growth of V. umbellata and E. frumentacea. Further research is needed to identify the specific allelochemicals involved and their mechanisms of action and to explore the broader ecological and agricultural implications of these interactions. [ABSTRACT FROM AUTHOR]

Plant reproduction is often inhibited by herbivorous leaf damage, which affects the resource pool allocated for reproduction. Rhododendron kaempferi var. kaempferi is a semi‐evergreen shrub widely distributed in Japan, and its leaves are occasionally damaged by sawfly larvae (Arge similis). This species is partially self‐compatible, but its selfed seedlings suffer from inbreeding depression. Our study aimed to clarify (1) the magnitude of herbivorous damage under natural conditions, (2) the effects of foliage damage on seed number and mass, and (3) the possibility of selective abortion of selfed seeds to maintain outcrossed seed production under resource limitation. In the 2022 survey, 2 of the 20 ramets observed were collectively parasitized by sawfly larvae, and the most damaged ramet had a 59.6% foliage loss. In contrast, the herbivorous damage in 2023 was consistently low throughout the growing season, averaging a 3.2% loss. Leaf excision reduced the seed number per fruit (i.e., low seed‐set rate) but did not affect the individual seed mass. The outcrossing rate of the excision treatment (81.7%) was significantly higher than that of the control (72.0%). The values of seed‐set rate × outcrossing rate were 0.172 for the excision treatment and 0.171 for the control, nearly equal. Our results indicated that (1) sawfly larvae damage was concentrated on a few specific plants, (2) intense foliage damage reduced seed number but not seed mass, and (3) R. kaempferi mitigated the decline in outcrossed seed production by the abortion of selfed seeds when leaves were intensively damaged. [ABSTRACT FROM AUTHOR]

This study investigated chemical compositions and biocidal activities from the aerial parts of Rhododendron thymifolium against Tribolium castaneum, Lasioderma serricorne, and Ditylenchus destructor. In total, 13 components were isolated from the aerial parts of R. thymifolium by chromatographic separation techniques. Based on the results of MS, 1H NMR, and 13C NMR spectrometry, their structures were determined as ent-kaurane-16β-ol (1), pentacosane (2), undecanoic acid, ethyl ester (3), 1-Tridecanethiol (4), 1-Dodecanol (5), 4-Methyl-7-hydroxycoumarin (6), tertradecan-1-ol (7), apocynin (8), 3-Methoxy-4-methylbenzaldehyde (9), scopoletin (10), hyperin (11), quercetin (12), acetophenone (13). In addition, ent-kaurane-16β-ol (1) was isolated from R. thymifolium for the first time. Then, the insecticidal toxicities against T. castaneum, L. serricorne, and D. destructor. of compounds 1–13 were evaluated, and the results showed that apocynin (8) and acetophenone (13) exhibited obvious contact activity against the storage pests with LD50 values of 6.46 and 8.72 μg/adult respectively. Acetophenone (13) showed excellent contact activity against D. destructor with LC50 values of 0.08 mg/mL. The study clearly showed the active fractions from R. thymifolium have might potential to be developed into potential compounds on storage insect prevention. [ABSTRACT FROM AUTHOR]

The N2-fixing trees Alnus spp. have been widely encroaching into boreal peatlands, but the nutrient responses of native vascular plants remain unclear. Here, we compared nutrient concentrations and isotope signal of six common plants (Betula fruticosa, Salix rosmarinifolia, Vaccinium uliginosum, Rhododendron tomentosum, Chamaedaphne calyculata, and Eriophorum vaginatum) between Alnus hirsuta island and open peatland and assessed plant nutrient responses to A. hirsuta encroachment in boreal peatlands. Alnus hirsuta encroachment increased nitrogen (N) concentration of leaf, branch, and stem. Despite no significant interspecific difference in branch and stem, the increment magnitude of leaf N concentration varied among species, with greatest magnitude for R. tomentosum (55.1% ± 40.7%) and lowest for E. vaginatum (9.80% ± 4.40%) and B. fruticosa (18.4% ± 10.7%). Except for E. vaginatum, the significant increase in δ15N occurred for all organs of shrubs, with interspecific differences in change of leaf δ15N. According to the mass balance equation involving leaf δ15N, R. tomentosum and E. vaginatum, respectively, obtained highest (40.5% ± 19.8%) and lowest proportions (–14.0% ± 30.5%) of N from A. hirsuta. Moreover, the increment magnitudes of leaf N concentration showed a positive linear relationship with the proportion of N from A. hirsuta. In addition, A. hirsuta encroachment reduced leaf phosphorus (P) concentration of deciduous shrubs (i.e., B. fruticosa, S. rosmarinifolia, and V. uliginosum), thus increasing N:P ratio. These findings indicate that Alnus encroachment improves native plant N status and selectively intensifies P limitation of native deciduous shrubs, and highlight that the N acquisition from the symbiotic N2-fixing system regulates plant N responses in boreal peatlands. [ABSTRACT FROM AUTHOR]

Increased temperatures are altering rates of organic matter (OM) breakdown in stream ecosystems with implications for carbon (C) cycling in the face of global change. The metabolic theory of ecology (MTE) provides a framework for predicting temperature effects on OM breakdown, but differences in the temperature dependence of breakdown driven by different organismal groups (i.e., microorganisms vs. invertebrate detritivores) and litter species remain unresolved. Over two years, we conducted 12 60‐day leaf litterbag incubations in 20 headwater streams in the southern Appalachian Mountains (USA). We compared temperature dependence (as activation energy, Ea) between microbial and detritivore‐mediated breakdown, and between a highly recalcitrant (Rhododendron maximum) and a relatively labile (Acer rubrum) leaf species. Detritivore‐mediated breakdown had a higher Ea than microbial breakdown for both leaf species (Rhododendron: 1.48 > 0.56 eV; Acer: 0.97 > 0.29 eV), and Rhododendron breakdown had a higher Ea than Acer breakdown for both organismal groups. Similarly, the Ea of total (coarse‐mesh) Rhododendron breakdown was higher than the Ea of total Acer breakdown (0.89 > 0.52 eV). These effects for total breakdown were large, implying that the number of days to 95% mass loss would decline by 40% for Rhododendron and 26% for Acer between 12°C (our mean temperature value) and 16°C (+4°C, reflecting projected increases in global surface temperature due to climate change). Despite patterns in Ea, overall breakdown rates were higher for microbes than detritivores, and for Acer than Rhododendron over most of our temperature gradient. Additionally, the Ea for a subset of the microbial breakdown data declined from 0.40 to 0.22 eV when fungal biomass was included as a model predictor, highlighting the key role of fungi in determining the temperature dependence of litter breakdown. Our results imply that, as streams warm, routing of leaf litter C to detritivore‐mediated fates will increase faster than predicted by previous studies and MTE, especially for labile litter. As temperatures rise, earlier depletion of autumn‐shed, labile leaf litter combined with rapid breakdown rates of recalcitrant litter could exacerbate seasonal resource limitation and alter carbon storage and transport dynamics in temperate headwater stream networks. [ABSTRACT FROM AUTHOR]

Rhododendron resources are abundant in China, and hybridization breeding technology is the primary method for cultivating Rhododendron varieties. In order to optimize the utilization of wild Rhododendron resources for distant hybridization, this study took three horticultural varieties of Rhododendron subgenus Tsutsusi and the Rhododendron decorum Franch. of the subgenus Hymenanthes as the research objects, and the cross-compatibility between subgenera was analyzed from the aspects of pollen tube growth and ovary and seed development. At the same time, the statistics of ovary swelling rate and fruit bearing rate, numbers of capsule seeds, 1000 seed weight of hybrid seeds, germination rate, green seedling rate, and other indexes were analyzed to comprehensively evaluate hybrid fertility. The results showed that there was obvious pre-fertilization and post-fertilization barriers existing in the hybridization of Rhododendron × hybridum hort. and R. decorum. During the growth of pollen tubes, a large amount of callus appeared, which led to the entanglement, distortion, and abnormal development of the pollen tubes; only part of the pollen tubes entered into the ovary or ovule. The pre-fertilization barriers can be overcome by early pollination and delayed pollination. According to the observation of the ovary paraffin section, 45 d after pollination, the seed was shriveled and developed abnormally. The comprehensive evaluation of hybrid fertility showed that 'Sima' × R. decorum was fertile, 'Yin Taohong' × R. decorum was a weakly fertile, and 'Little Taohong' × R. decorum was sterile. This study provided a scientific basis for intergeneric hybridization breeding between the subgenus Tsutsusi and the subgenus Hymenanthes. [ABSTRACT FROM AUTHOR]

Two new species of Vireya Rhododendron, Rhododendron mulyaniae sp. nov. and R. engelbertii sp. nov. were discovered in Tambrauw, Papua, Indonesia. Rhododendron mulyaniae resembles R. angiense in that the scales under the leaf are dendroid, but differs in having elliptic to narrowly elliptic leaves, lacking hairs on petiole, having a tubular funnel shaped corolla. Rhododendron engelbertii resembles to R. carstensense in leaf shape but differs by having narrowly tapering leaf base, scales present on the petiole, and a corolla densely scaly on the outside. Detailed descriptions, illustrations and provisional conservation threat status of these newly described species are provided. [ABSTRACT FROM AUTHOR]

Summary: Rhododendron boninense Nakai, illustrated here, is a critically endangered endemic rhododendron from the Ogasawara Islands, whose population was once reduced to a single individual. Since the 1980s, Koishikawa Botanical Garden has made efforts to propagate and reintroduce this species to its original habitat, resulting in a current population of 60 mature plants and several natural seedlings. The pure white corolla, which lacks a nectar guide, is distinctive among related rhododendrons, suggesting that a pollinator shift occurred after colonisation of the Ogasawara Islands, where the ancestral pollinators are absent. [ABSTRACT FROM AUTHOR]

The article discusses the extended distribution of Kuepferia doxiongshangensis to Sikkim Himalaya and comments on the name "Gentiana taylorii Harry Sm." Two species of Euphorbia were also discovered in West Bengal during botanical excursions. The taxonomic treatment of these species, along with detailed descriptions, habitat information, and distribution, is provided. The study highlights the importance of these findings in expanding our understanding of plant diversity in these regions. [Extracted from the article]

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Fertilization significantly influences soil quality and its sustainable use in urban garden maintenance. The widespread application of inorganic fertilizers has raised ecological concerns due to their potential environmental impacts. Organic fertilizers, while beneficial, often have slow effects and are costly. Biofertilizers, with their eco-friendly nature and low carbon footprint, are gaining attention for their multifaceted role in supporting plant growth. Despite the focus on fruit trees, vegetables, and medicinal plants, ornamental plants have been understudied. This study aims to evaluate the efficacy of a novel microbial fertilizer, 'natural soil biotin', on Rhododendron plants, specifically the Azalea hybrid 'Carnation'. The study employed a comparative approach to assess the impact of different fertilization strategies on soil properties, microbial diversity, enzyme activity, plant morphology, and physiological parameters. The application of 'natural soil biotin' was compared with the use of inorganic and organic fertilizers. The combined application of 'natural soil biotin' was found to effectively enhance soil properties and mitigate the impact of other fertilizers on soil pH. It also improved the relative abundance of beneficial microbial groups such as Proteobacteria, Ascomycota, and Basidiomycota. Furthermore, the mixed application significantly increased the activities of urease and sucrase in Rhododendron plants, which promoted their growth, development, and stress resistance. The results indicate that the mixed application of 'natural soil biotin' with inorganic and organic fertilizers not only improved the soil quality but also enhanced the efficiency of fertilizer utilization. This approach led to increased economic and environmental benefits in Rhododendron cultivation. The findings contribute to the foundation for soil improvement and ecological restoration, suggesting that 'natural soil biotin' could be a promising alternative or supplement to traditional fertilization methods in sustainable landscape architecture. [ABSTRACT FROM AUTHOR]

This in vitro and in silico study was designed to validate acclaimed anti-inflammatory or pain-relieving properties of fermented ethnic beverages prepared from Rhododendron or Guras flowers in the Singalila ridge- the famous Rhododendron growing region of the Himalayas. Traditional beverages Guras wine and its distilled version Guras Raksi were considered in this study which were collected from Gairibas, a village situated in Indo-Nepal Singalila Ridge of the Himalayas. In vitro protein (albumin) denaturation inhibition assay was conducted to evaluate anti-inflammatory activity of the samples and later GC-MS analysis was carried out to identify anti-inflammatory compounds present in those beverages. From GC-MS results, eleven major metabolites such as 5-hydroxymethylfurfural; quinic acid; clionasterol; l-(+)-ascorbic acid, 2,6-dihexadecanoate; d-sorbitol; cis-cinnamic acid; tyrosol; lupeol; methyl commate A; 2-hydroxy-gamma-butyrolactone; and 1,3-propanediol, 2-(hydroxymethyl)- 2-nitro- were chosen for molecular docking with human cyclooxygenase-1 (hCOX-1), an important targets in the drug-design for nonsteroidal anti-inflammatory drugs. Among all query compounds, phytosterol- clionasterol and triterpenoid- lupeol and methyl commate A exhibited considerably high binding energy scores (<-8 kcal/mol) even compared to anti-inflammatory drugs- acetaminophen and ibuprofen. Outcome of this research affirmed the potential of Gurasbased traditional drinks in the healing of different forms of high-altitudinal stress induced pain. [ABSTRACT FROM AUTHOR]

Rhododendron williamsianum Rehder & E. H. Wilson 1913, is a plant with important horticultural value. Here we report its chloroplast genome. The total length of the chloroplast genome was 205,424 bp, with a GC content of 35.8%. It consisted of a 107,968 bp large single copy, a 2606 bp small single copy, and a pair of 47,425 bp inverted repeats separating them. Within the chloroplast genome, there were a total of 110 unique genes, which included 76 protein-coding genes, 4 rRNA genes, and 30 tRNA genes. Our phylogenetic analyses indicated that R. williamsianum was closely genetically related to R. sutchuenense and R. jingangshanicum. The findings from this study not only contribute to the genetic database of Rhododendron plants but also have implications for evolutionary research within the family Ericaceae. [ABSTRACT FROM AUTHOR]

Within the scope of eco-friendly green technology, the interest in alternative biosorbents in heavy metal removal from water is increasing. However, chemical- or thermal- activation pretreatments are needed for biomass to have good biosorbent properties. The thermal processes such as carbonization and pyrolysis, which are frequently applied for activation, cause high energy consumption and lead to severe degradation in biomass structure and in surface functional groups. The importance of this study stems from the torrefaction of various biomass species at low temperatures for the purpose of biosorbent preparation and the testing of the biosorbents' heavy metal removal capacity. Thus, biomasses such as tea production waste, corn stalk, pine cone, brown seaweed, rhododendron, and grape seed were torrefied at temperatures of 150–300 °C and the obtained biosorbents were used to remove Pb(II), Cr(VI), and Cd(II) from aqueous solution where concentrations of each metal were 1000 ppm. Effects of the torrefaction temperature, solution temperature, and solution pH on metal uptake were studied by batch adsorption tests. It was determined that the biomasses torrefied at 150 °C has the optimum metal removal capacity. When torrefied corn stalk was used, 17.9 mg/g for Pb(II) and 16.8 mg/g Cr(VI) could be separated from solution, while the maximum Cd(II) uptake was 20.8 mg/g for torrefied tea production waste. It was concluded that the heavy metal removal capacity of biosorbents prepared by low-temperature torrefaction is at non-negligible levels. [ABSTRACT FROM AUTHOR]

Rhododendrons produce a variety of methoxyflavonoids, including rarely found 3-methoxyflavonoids and 5-methoxyflavonoids. It was thus suggested that they have a series of regiospecific flavonoid O-methyltransferases (FOMTs). The 18 Class II O-methyltransferase (OMT) genes were retrieved from the Rhododendron delavayi genome, designating them as RdOMTs. A comprehensive biochemical characterization of RdOMTs was performed to identify functional FOMTs. The FOMT activity of recombinant RdOMTs was assayed with flavonoid substrates of different subclasses. Among the examined RdOMTs, RdOMT3, RdOMT10, and RdOMT12 showed FOMT activity for diverse flavonoids. In particular, RdOMT3 consumed only flavonols as a substrate. Structural analyses of the methylated products demonstrated that RdOMT3, RdOMT10, and RdOMT12 catalyze regiospecific methylation of flavonoids at the 3'/5'-, 3-, and 4'-hydroxyl groups, respectively. Their broad substrate spectrum and different regiospecificity suggest that these RdOMTs contribute to the formation of complex methoxyflavonoids in R. delavayi. Bioconversion of flavonoids using E. coli harboring each RdOMT demonstrated that RdOMT3, RdOMT10, and RdOMT12 are useful tools for the biotechnological production of valuable methoxyflavonoids, including the rarely found 3-methoxyflavonoids. [ABSTRACT FROM AUTHOR]

Rhododendron petals are considered high‐value owing to their commercial utility, national/state flower status in certain countries, and bioactive potential from recent studies. Profiling and quantitative analysis of the bioactive metabolites would evaluate if they can be natural sources. This study is focused on the comprehensive profiling of secondary metabolites in the hot aqueous petal extracts of Red and Pink Rhododendron flowers (Rhododendron arboreum and Rhododendron campanulatum) using separation and fragmentation patterns from mass spectrometry (MS) (gas chromatography‐MS and liquid chromatography‐tandem MS) and chemical shifts from proton‐nuclear magnetic resonance spectroscopy. The complementary analytical platforms highlighted the petals to be rich in promising bioactive molecules such as quinic acid, chlorogenic acid (caffeoyl quinic acid), protocatechuic acid, coumaroyl quinic acids, catechin, epigallocatechin, and shikimic acid. The analysis also reflected the activity of shikimic acid, phenolic acid, and flavonoid biosynthetic pathways in Rhododendron flowers. These metabolites are well reported for their bioactive potential as anti‐oxidative, anti‐viral, anti‐cancerous, anti‐diabetic, anti‐inflammatory, etc. While the quantitative and multivariate analysis showed variations in the levels of phenolic acids and flavonoids, it is established that red and pink Rhododendron flower petals are a rich source of bioactive phytochemicals of interest to the phytochemical Industry. [ABSTRACT FROM AUTHOR]

The Japanese subalpine zone is dominated by an ecologically important forest biome, subalpine coniferous forest, constituting a distinct assemblage of cold‐tolerant angiosperm and conifer species. While being relatively intact compared to other forest biomes in Japan, subalpine coniferous forests are under significant threat from deer browsing, global warming and small population size effects. However, there is a severe lack of genetic resources available for this biome's major constituent plant species. This study aimed to develop chloroplast genome‐based genetic resources for 12 widespread subalpine tree and shrub species (7 angiosperms and 5 conifers) via genome skimming of whole‐genomic DNA using short reads (100–150 bp in length). For 10 species, whole chloroplast genomes were assembled via de novo‐based methods from 4 to 10 individuals per species sampled from across their ranges in Japan and, for non‐Japanese endemic species, elsewhere in northeast Asia. A total of 566 single nucleotide polymorphisms for Japanese samples and 768 for all samples (varying from 2 to 202 per species) were identified which were distributed in geographically restricted lineages in most species. In addition, between 9 and 58 polymorphic simple sequence repeat regions were identified per species. For two Ericaceae species (Rhododendron brachycarpum and Vaccinium vitis‐idaea) characterised by large chloroplast genomes, de novo assembly failed, but single nucleotide polymorphisms could be identified using reference mapping. These data will be useful for genetic studies of species taxonomic relationships, investigating phylogeographic patterns within species, developing chloroplast‐based markers for conservation genetic studies and has potential application for studies of environmental and ancient DNA. [ABSTRACT FROM AUTHOR]

UV-B stress can affect plant growth at different levels, and although there is a multitude of evidence confirming the effects of UV-B radiation on plant photosynthesis, there are fewer studies using physiological assays in combination with multi-omics to investigate photosynthesis in alpine plants under stressful environments. Golden 2-like (G2-like/GLK) transcription factors (TFs) are highly conserved during evolution and may be associated with abiotic stress. In this paper, we used Handy-PEA and Imaging-PAM Maxi to detect chlorophyll fluorescence in leaves of Rhododendron chrysanthum Pall. (R. chrysanthum) after UV-B stress, and we also investigated the effect of abscisic acid (ABA) on photosynthesis in plants under stress environments. We used a combination of proteomics, widely targeted metabolomics, and transcriptomics to study the changes of photosynthesis-related substances after UV-B stress. The results showed that UV-B stress was able to impair the donor side of photosystem II (PSII), inhibit electron transfer and weaken photosynthesis, and abscisic acid was able to alleviate the damage caused by UV-B stress to the photosynthetic apparatus. Significant changes in G2-like transcription factors occurred in R. chrysanthum after UV-B stress, and differentially expressed genes localized in the Calvin cycle were strongly correlated with members of the G2-like TF family. Multi-omics assays and physiological measurements together revealed that G2-like TFs can influence photosynthesis in R. chrysanthum under UV-B stress by regulating the Calvin cycle. This paper provides insights into the study of photosynthesis in plants under stress, and is conducive to the adoption of measures to improve photosynthesis in plants under stress to increase yield. [ABSTRACT FROM AUTHOR]

Rhododendron arboreum, belonging to the Ericaceae family, is primarily distinguished by its vivid red or light pink flowers. The flower is often known as "Lali Gurans" in Nepali and is recognized as the official flower of Nepal. Rhododendron flowers have traditionally been used to cure various human ailments including blood dysentery, headache, asthma, cough, stomachache, fever, inflammation and fungal infections. Moreover, it has medicinal and pharmacological importance. The present study aimed to investigate the beneficial effects of dietary laligurans flower as the growth promotor and immunostimulant in common carp (Cyprinus carpio) fingerlings. Rhododendron flowers taken from the Phulchowki hills of Kathmandu Valley were taxonomically identified by the National Herbarium Center, Govt. of Nepal following ethanol (70%) extract (LGE) and plain powder (LGP) were prepared. There was a total of 7 diets used in the study in which the control diet (T1) did not have any supplementation. The other diets 0.2% (T2), 0.4% (T3), 0.8% (T4) and 1.6% (T5) were supplemented with ethanol extract (LGE) while 0.2% (T6) and 0.4% (T7) were with dry powder (LGP). The experiment was specifically built as a recirculating aquaculture system and was carried out at the Central Fisheries Promotion and Conservation Center (CFPCC), Government of Nepal located in Balaju, Kathmandu. The aquaria were divided into 7 diets, with 3 replicates for each diet hence, fingerlings of common carp (Cyprinus carpio) weighing 2.43±0.21g allocated to 21 glass aquaria randomly. The fish were provided with food equivalent to 5% of their body weight and the sampling was conducted after a period of 90 days of feeding experiments. Statistically significant growth (p< 0.05) was seen in all the treated fish. However, carp fed with LGE performed better and the maximum amount of growth was obtained in carp fed with the 0.8% (T4) diet. The levels of total protein, albumin and globulin demonstrated an upward trend, but the levels of SGOT, SGPT and ALP showed a downward trend when compared to the control and LGP-treated diet. The haematological parameters of the fish given a T4 treated diet were within the normal range, however the levels of hemoglobin (Hb) and hematocrit (PCV) were elevated. Based on the evidence, it is advised that aqua culturists use the ethanol extract of laligurans flower to promote fish growth and improve the socioeconomic activities of farmers. [ABSTRACT FROM AUTHOR]

Rhododendron ponticum (L.) is a highly invasive, non-native woody shrub that prevents tree regeneration and kills native flora. Achieving successful control of rhododendron can be difficult due to its thick waxy leaf surfaces, which discourage the absorption of foliar-applied herbicides. The spray adjuvant Mixture B NF® has therefore been used for many years to improve the efficacy, absorption, and rainfastness of foliar applications of glyphosate. We established an experiment to test if alternative non-hazardous adjuvants could be equally effective. Treatments were applied as foliar sprays and then subjected to artificial rainfall to examine rainfastness. We found that the non-hazardous adjuvants Codacide Oil® and Toil® (both based on rapeseed oil), and also SU Wett®, offered little or no benefit to the efficacy or rainfastness of glyphosate applications to rhododendron. However, further research using these adjuvants on other weed species is recommended. The only treatment in our study that showed acceptable levels of rhododendron control was glyphosate plus Mixture B NF®. Current recommendations for the control of rhododendron are therefore still valid. When foliar sprays of rhododendron bushes are required, apply 2.88–3.60 kg a.i. ha− 1 glyphosate and add Mixture B NF® adjuvant at a rate of 2 per cent of final spray volume. A minimum rain-free period of 6 h should occur after application of glyphosate products to any weed type, but if there is a risk of rainfall occurring earlier than this, and the application cannot be delayed, the use of Mixture B NF® is likely to improve rainfastness, reduce run-off and improve control. [ABSTRACT FROM AUTHOR]

In the Arctic tundra, warming is anticipated to stimulate nutrient release and potentially alleviate plant nutrient limitations. Typically simulated by fertilization experiments that saturate plant nutrient demand, future increases in soil fertility are thought to favor ectomycorrhizal (EcM) over ericaceous shrubs and have often been identified as a key driver of Arctic shrub expansion. However, the projected increases in fertility will likely vary in their alleviation of nutrient limitations. The resulting responses of shrubs and their mycorrhizae across the gradient of nutrient limitation may be nonlinear and could contradict the current predictions of tundra vegetation shifts. We compared the functional responses of two dominant shrubs, EcM dwarf birch (Betula nana) and ericaceous Labrador tea (Rhododendron tomentosum), across a long‐term nitrogen and phosphorus fertilization gradient experiment in Arctic Alaska. Using linear mixed‐effects modeling, we tested the responses of shrub cover, height, and root enzyme activities to soil fertility. We found that B. nana cover and height linearly increased with soil fertility. In contrast, R. tomentosum cover initially increased, but decreased after surpassing the intermediate levels of increased soil fertility. Its height did not change. Enzyme activity did not respond to soil fertility on EcM‐colonized B. nana roots, but sharply declined on R. tomentosum roots. Overall, the nonlinear responses of shrubs to our fertility gradient demonstrate the importance of experiments grounded in replicated regression design. Our results indicate that under moderate increases in soil fertility, Arctic shrub expansion may not only include deciduous EcM shrubs but also ericaceous shrubs. Regardless of shifts aboveground, changes in root enzyme activity belowground point to some EcM shrub species playing a more influential role in tundra soils; as EcM roots remained steady in their liberation of soil organic nutrients with heightened soil fertility, degradative root enzyme activity on the dominant ericaceous shrub dropped—in some instances with even the slightest increase in fertility. [ABSTRACT FROM AUTHOR]

In Japan, secondary forests associated with agriculture (satoyama) had been maintained traditionally by small-scale clearcutting and short-rotation coppice forestry. After forest management was discontinued due to modernization, shade-intolerant, deciduous trees such as Q. serrata and Q. variabilis have become dominant in many secondary forests of southwestern Japan. In recent years, however, tree death from Japanese oak wilt has become wide-spread. To identify forest communities that will be most affected by oak wilt, we investigated stand structure and species composition in a 64-ha unmanaged secondary forest in Kobe, Japan. We identified three forest communities using cluster analysis of 27 survey plots. We then analyzed and visualized vegetation similarity among the communities using non-metric multidimensional scaling (nMDS). In secondary forests, Pinus densiflora–Rhododendron macrosepalum and Quercus serrata–Quercus variabilis communities, which established after pine wilt were identified. We also found communities dominated by Cryptomeria japonica, a plantation species. We predicted that Quercus serrata–Quercus variabilis communities will experience significant vegetation change after oak wilt and become low-statured, evergreen-deciduous forests. These communities, therefore, should be prioritized for active management by small-scale clear cutting to prevent further spread of oak wilt and subsequent biodiversity decline. [ABSTRACT FROM AUTHOR]

Cardamine diphylla is an understory herb of rich forests that exhibits a wintergreen life history strategy in western North Carolina. Unlike many forest floor plants, C. diphylla is able to persist under the evergreen shrub Rhododendron maximum, which is known to inhibit the growth of woody and herbaceous plants. We compared morphological and chemical characteristics of C. diphylla leaves in areas of a mesic cove forest with and without R. maximum during the winter. We also compared soil properties and the taxonomic richness of co-occurring herbaceous and woody plants. Results showed that C. diphylla growing under R. maximum produced significantly less foliar biomass but had significantly higher levels of foliar nitrogen and sulfur. Plants under R. maximum also had a higher proportion of green (rather than purple) abaxial leaf surfaces. Soils under R. maximum contained significantly less total nitrogen and humic matter, but cation exchange capacity and pH did not differ between the two areas. Compared to the surrounding forest, plots in R. maximum thickets supported 35% fewer woody taxa and 41% fewer herbaceous taxa, demonstrating the challenges of this microhabitat to understory plants. The ability of C. diphylla to persist under R. maximum may be advantageous if R. maximum continues its opportunistic expansion in southern Appalachian forests. [ABSTRACT FROM AUTHOR]

Aluminum (Al) toxicity is an important factor restricting the normal growth of plants in acidic soil. Rhododendron (Ericaceae) can grow relatively well in acidic soil. To uncover the adaptive mechanisms of photosynthesis under Al stress, the influence of Al stress on the photosynthetic activities of Al-sensitive (Baijinpao) and Al-resistant (Kangnaixin) rhododendron cultivars was examined by measuring gas exchange, chlorophyll fluorescence, and the modulated reflection of light at 820 nm. Under Al stress conditions, the net photosynthetic rate and stomatal conductance of the rhododendron leaves decreased, whereas the intercellular CO2 concentration increased. The Al stress treatment damaged the oxygen-evolving complex of the rhododendron seedlings, while also inhibiting electron transport on the photosystem II (PSII) donor side. In addition, the exposure to Al stress restricted the oxidation of plastocyanin (PC) and the photosystem I (PSI) reaction center (P700) and led to the re-reduction of PC+ and P700+. The comparison with Kangnaixin revealed an increase in the PSII connectivity in Baijinpao. Additionally, the donor-side electron transport efficiency was more inhibited and the overall activity of PSII, PSI, and the intersystem electron transport chain decreased more extensively in Baijinpao than in Kangnaixin. On the basis of the study findings, we concluded that Al stress adversely affects photosynthesis in rhododendron seedlings by significantly decreasing the activity of PSII and PSI. Under Al stress, Kangnaixin showed stronger tolerance compared with Baijinpao. [ABSTRACT FROM AUTHOR]

Rhododendron delavayi Franch. predominantly thrives in broad-leaved evergreen forests and bushes at altitudes of 1,200–3,200 meters. It favors a cool, moist climate and thrives in acidic soils. Due to its high ornamental, medicinal, and scientific values, understanding its ecological needs and optimal cultivation ranges is crucial. This study analyzing the key environmental factors and their thresholds affecting its distribution and predicts the future potential habitats of R. delavayi using existing distribution data alongside current and projected climate data. The results indicate that the primary environmental influencers are soil pH (4.9–5.4), precipitation in the driest month (10–20 mm), and altitude, contributing 41.8, 24.1, and 18.3%, respectively. It also shows a declining trend in suitable habitats: from 27.75 × 104 km² under current conditions, to 3.69 × 104 km² by the 2050s, and further to 2.65 × 104 km² by the 2070s. [ABSTRACT FROM AUTHOR]

Rhododendron arboreum: Sm., also known as Burans is traditionally used as an antiinflammatory, anti-diabetic, hepatoprotective, adaptogenic, and anti-oxidative agent. It has been used since ancient times in Indian traditional medicine for various liver disorders. However, the exact mechanism behind its activity against NAFLD is not known. The aim of the present study is to investigate the molecular mechanism of Rhododendron arboreum flower (RAF) in the treatment of NAFLD using network pharmacology and molecular docking methods. Bioactives were also predicted for their drug-likeness score, probable side effects and ADMET profile. Protein-protein interaction (PPI) data was obtained using the STRING platform. For the visualisation of GO analysis, a bioinformatics server was employed. Through molecular docking, the binding affinity between potential targets and active compounds were assessed. A total of five active compounds of RAF and 30 target proteins were selected. The targets with higher degrees were identified through the PPI network. GO analysis indicated that the NAFLD treatment with RAF primarily entails a response to the fatty acid biosynthetic process, lipidmetabolic process, regulation of cell death, regulation of stress response, and cellular response to a chemical stimulus. Molecular docking andmolecular dynamic simulation exhibited that rutin has best binding affinity among active compounds and selected targets as indicated by the binding energy, RMSD, and RMSF data. The findings comprehensively elucidated toxicity data, potential targets of bioactives and molecular mechanisms of RAF against NAFLD, providing a promising novel strategy for future research on NAFLD treatment. [ABSTRACT FROM AUTHOR]

Lysine acetylation of proteins plays a critical regulatory function in plants. A few advances have been made in the study of plant acetylproteome. However, until now, there have been few data on Rhododendron chrysanthum Pall. (R. chrysanthum). We analyzed the molecular mechanisms of photosynthesis and stress resistance in R. chrysanthum under UV−B stress. We measured chlorophyll fluorescence parameters of R. chrysanthum under UV−B stress and performed a multi−omics analysis. Based on the determination of chlorophyll fluorescence parameters, R. chrysanthum Y(NO) (Quantum yield of non−photochemical quenching) increased under UV−B stress, indicating that the plant was damaged and photosynthesis decreased. In the analysis of acetylated proteomics data, acetylated proteins were found to be involved in a variety of biological processes. Notably, acetylated proteins were significantly enriched in the pathways of photosynthesis and carbon fixation, suggesting that lysine acetylation modifications have an important role in these activities. Our findings suggest that R. chrysanthum has decreased photosynthesis and impaired photosystems under UV−B stress, but NPQ shows that plants are resistant to UV−B. Acetylation proteomics revealed that up- or down-regulation of acetylation modification levels alters protein expression. Acetylation modification of key enzymes of the Calvin cycle (Rubisco, GAPDH) regulates protein expression, making Rubisco and GAPDH proteins expressed as significantly different proteins, which in turn affects the carbon fixation capacity of R. chrysanthum. Thus, Rubisco and GAPDH are significantly differentially expressed after acetylation modification, which affects the carbon fixation capacity and thus makes the plant resistant to UV−B stress. Lysine acetylation modification affects biological processes by regulating the expression of key enzymes in photosynthesis and carbon fixation, making plants resistant to UV−B stress. [ABSTRACT FROM AUTHOR]

Rhododendron plants have ornamental, commercial, and medicinal value to people. Flavonoids are one of the components used in traditional remedies, and Rhododendron plants are found to be rich in flavonoids. Flavonoids can reduce the risk of human disease and participate in the regulation of antioxidant defense systems in response to heat stress. Rhododendron prefers cold climates, so the relatively high temperatures of cities affect the extraction of medicinal ingredients and limit the cultivation environment. Recent studies found that the exogenous application of calcium acts to alleviate heat stress in Rhododendron plants. This study explores the mechanism by which exogenous calcium alleviates heat stress and the role of flavonoids in regulating the antioxidative system in Rhododendron × pulchrum Sweet using combined transcriptomic and metabolomic methods. The activities of peroxidase, catalase and superoxide enzymes were found to increase in response to heat stress and external CaCl2 in the leaves of R. × pulchrum. In total, 433 metabolic components and 370 DEGs were identified as being differentially expressed in response to heat stress and external calcium chloride (CaCl2) in the leaves of R. × pulchrum. These results illustrate that heat stress induces oxidative stress and that external CaCl2 can enhance the heat tolerance of Rhododendron. Flavonoid compounds are responsible for the antioxidant scavenging of reactive oxygen species in R. × pulchrum leaves exposed to heat stress and external calcium. [ABSTRACT FROM AUTHOR]

Six ionone glycosides (1–3 and 5–7), including three new ones, named capitsesqsides A−C (1–3), together with an eudesmane sesquiterpenoid glycoside (4) and three known triterpenoid saponins (8–10) were isolated from Rhododendron capitatum. The structures of these compounds were determined by extensive spectroscopic techniques (MS, UV, 1D-NMR, and 2D-NMR) and comparison with data reported in the literature. The absolute configurations were determined by comparison of the experimental and theoretically calculated ECD curves and LC-MS analyses after acid hydrolysis and derivatization. The anti-inflammatory activities of these compounds were evaluated in the LPS-induced RAW264.7 cells. Molecular docking demonstrated that 2 has a favorable affinity for NLRP3 and iNOS. [ABSTRACT FROM AUTHOR]

Summary: The present study describes two new Ditylenchus species, isolated from the growing medium of Rhododendron simsii imported from Japan, at the Ningbo plant quarantine laboratory, Ningbo, P.R. China. Ditylenchus parvicauda n. sp. is an amphimictic species. Females have six incisures in the lateral fields, a medium length slim body, a short delicate stylet with asymmetrical stylet knobs, the secretory-excretory (S-E) pore located posterior to the isthmus and in the anterior region of the basal pharyngeal bulb, a posteriorly located vulva (V = 80.9-83.0), post-uterine sac (PUS) tube-like, and the tail cylindrical, tapering gradually towards finely rounded terminus. Males are similar to females in general morphology and have 10.1-14.9 μ m long spicules. The second new species, D. gracicauda n. sp. is characterised by having a long and slender body, the presence of a vulval flap, four lines in the lateral field, a narrow and low lip region not offset, the S-E pore located posterior to the isthmus but not in the anterior region of the basal pharyngeal bulb, a posteriorly located vulva (V = 71.1-76.2), a short post-vulval uterine sac short (4.5-9.2 μ m), and the tail slender, tapering gradually towards finely rounded to wedge-shaped terminus. The two new species were also characterised molecularly using 18S, ITS and the D2-D3 expansion segments of 28S rRNA genes. Our phylogenetic analyses showed their independent place among available Ditylenchus species. Several Ditylenchus species are regulated pests, and the introduction of these species into a new environment may result in diseases among native plants or vegetation in the area. Therefore, careful attention must be directed towards newly discovered species, particularly those under quarantine observation. [ABSTRACT FROM AUTHOR]

Superoxide dismutases (SODs) are the first line of defense in the antioxidant defense system, and they play an essential role in various adversity stress adaptations in Rhododendron. In this study, 9 Rhododendron simsii SODs (RsSODs) and 11 Rhododendron delavayi SODs (RdSODs) genes were identified in the genomes of R. simsii and R. delavayi. Phylogenetic relationship analysis classified SOD proteins from two Rhododendron species and other related species into three subfamilies. The results of gene structure and conserved motif analysis show that SOD proteins are strongly evolutionarily conserved, and SODs of the same subfamily have similar motif distributions, positions, and lengths. Twenty-two light-responsive elements, eight phytohormone regulatory elements, five adversity stress-related elements, and three growth and development regulatory elements were detected in the RsSOD and RdSOD promoters. Quantitative real-time fluorescence polymerase chain reaction analysis showed that among the 20 candidate genes, except for RdCSD5, the other SODs were expressed in at least one of four tissues, and all of these gene family members had high expression levels in the leaves. We then investigated the response of the RsSOD and RdSOD gene families to high-temperature stress in combination with the following specific stressors: abscisic acid, ethephon, and hydrogen peroxide treatments, followed by high-temperature stress. Different degrees of upregulated expression of the detected SOD gene family members were found for exogenous reagent treatments and different times of high-temperature stress. Thus, we provide a basis for the further functional characterization of SOD genes in R. simsii and R. delavayi in the future. [ABSTRACT FROM AUTHOR]

Our study aims to identify the mechanisms involved in regulating the response of Rhodoendron Chrysanthum Pall. (R.chrysanthum) leaves to UV-B exposure; phosphorylated proteomics and metabolomics for phenolic acids and plant hormones were integrated in this study. The results showed that UV-B stress resulted in the accumulation of salicylic acid and the decrease of auxin, jasmonic acid, abscisic acid, cytokinin and gibberellin in R.chrysanthum. The phosphorylated proteins that changed in plant hormone signal transduction pathway and phenolic acid biosynthesis pathway were screened by comprehensive metabonomics and phosphorylated proteomics. In order to construct the regulatory network of R.chrysanthum leaves under UV-B stress, the relationship between plant hormones and phenolic acid compounds was analyzed. It provides a rationale for elucidating the molecular mechanisms of radiation tolerance in plants. [ABSTRACT FROM AUTHOR]

High species diversity, hybridization potential, broad geographical dispersal range and ornamental characteristics (i.e., attractive size, shape, structure, flowers, and evergreen) have fetched a good international market for Rhododendron. However, most species are restricted to specific geographic areas due to their habitat specificity in acidic soil and cold climates, resulting many species being classified under threat categories of the IUCN. In this review, advances in research on Rhododendron for improvement to floral display quality and stress resistance have been described. The low genetic barrier among species has created opportunities for extensive hybridization and ploidy alteration for introducing quality and adaptive traits during the development of new varieties. Recent technological advances have supported investigations into the mechanism of flower development, as well as cold tolerance and pathogen resistance mechanisms in the Rhododendron. However, most of the species have limited adaptability to drought, line-tolerance, pathogen resistance, and high-temperature conditions and this resistance ability present in few species largely remains unexplored. Additionally, the available genetic diversity and genomic information on species, and possibilities for their application in molecular breeding have been summarized. Overall, genomic resource data are scarce in the majority of the members of this genus. Finally, various research gaps such as genetic mapping of quality traits, understanding the molecular mechanism of quality-related traits and genomic assortment in Rhododendron members have been discussed in the future perspective section. [ABSTRACT FROM AUTHOR]

With the depletion of the ozone layer, the intensity of ultraviolet B (UV-B) radiation reaching the Earth's surface increases, which in turn causes significant stress to plants and affects all aspects of plant growth and development. The aim of this study was to investigate the mechanism of response to UV-B radiation in the endemic species of Rhododendron chrysanthum Pall. (R. chrysanthum) in the Changbai Mountains and to study how exogenous ABA regulates the response of R. chrysanthum to UV-B stress. The results of chlorophyll fluorescence images and OJIP kinetic curves showed that UV-B radiation damaged the PSII photosystem of R. chrysanthum, and exogenous ABA could alleviate this damage to some extent. A total of 2148 metabolites were detected by metabolomics, of which flavonoids accounted for the highest number (487, or 22.67%). KEGG enrichment analysis of flavonoids that showed differential accumulation by UV-B radiation and exogenous ABA revealed that flavonoid biosynthesis and flavone and flavonol biosynthesis were significantly altered. GO analysis showed that most of the DEGs produced after UV-B radiation and exogenous ABA were distributed in the cellular process, cellular anatomical entity, and catalytic activity. Network analysis of key DFs and DEGs associated with flavonoid synthesis identified key flavonoids (isorhamnetin-3-O-gallate and dihydromyricetin) and genes (TRINITY_DN2213_c0_g1_i4-A1) that promote the resistance of R. chrysanthum to UV-B stress. In addition, multiple transcription factor families were found to be involved in the regulation of the flavonoid synthesis pathway under UV-B stress. Overall, R. chrysanthum actively responded to UV-B stress by regulating changes in flavonoids, especially flavones and flavonols, while exogenous ABA further enhanced its resistance to UV-B stress. The experimental results not only provide a new perspective for understanding the molecular mechanism of the response to UV-B stress in the R. chrysanthum, but also provide a valuable theoretical basis for future research and application in improving plant adversity tolerance. [ABSTRACT FROM AUTHOR]

Rhododendron is famous for its high ornamental value. However, the genus is taxonomically difficult and the relationships within Rhododendron remain unresolved. In addition, the origin of key morphological characters with high horticulture value need to be explored. Both problems largely hinder utilization of germplasm resources. Most studies attempted to disentangle the phylogeny of Rhododendron, but only used a few genomic markers and lacked large-scale sampling, resulting in low clade support and contradictory phylogenetic signals. Here, we used restriction-site associated DNA sequencing (RAD-seq) data and morphological traits for 144 species of Rhododendron, representing all subgenera and most sections and subsections of this species-rich genus, to decipher its intricate evolutionary history and reconstruct ancestral state. Our results revealed high resolutions at subgenera and section levels of Rhododendron based on RAD-seq data. Both optimal phylogenetic tree and split tree recovered five lineages among Rhododendron. Subg. Therorhodion (clade I) formed the basal lineage. Subg. Tsutsusi and Azaleastrum formed clade II and had sister relationships. Clade III included all scaly rhododendron species. Subg. Pentanthera (clade IV) formed a sister group to Subg. Hymenanthes (clade V). The results of ancestral state reconstruction showed that Rhododendron ancestor was a deciduous woody plant with terminal inflorescence, ten stamens, leaf blade without scales and broadly funnelform corolla with pink or purple color. This study shows significant distinguishability to resolve the evolutionary history of Rhododendron based on high clade support of phylogenetic tree constructed by RAD-seq data. It also provides an example to resolve discordant signals in phylogenetic trees and demonstrates the application feasibility of RAD-seq with large amounts of missing data in deciphering intricate evolutionary relationships. Additionally, the reconstructed ancestral state of six important characters provides insights into the innovation of key characters in Rhododendron. [ABSTRACT FROM AUTHOR]

Rhododendron is the largest genus in Ericaceae and is well known for its diversity and beauty of flowers present in different species, making it a much‐revered lineage of ornamental plants. Many species of Rhododendron are intolerant of high temperatures, which are becoming more common and intense in urban areas under global climate change. Therefore, the discovery and description of genes from heat‐tolerant Rhododendron lineages are essential in the development of new climate‐resilient cultivars. One such species known to be heat tolerant is Rhododendron × pulchrum Sweet. To better understand the genomics of heat tolerance in this species, we assembled a haplotype‐resolved and chromosome‐scale genome for R. × pulchrum, which had a genome size of 509 Mb; a scaffold N50 of 37 251 370 bp; and contained 35 610 genes. In addition, based on the same reannotation pipeline, we conducted pan‐genomic analyses for all seven available chromosome‐scale Rhododendron genomes and found 14 415 gene groups shared across all species and 18 018 gene groups distributed in the other species, including 1879 gene groups found in only a single species. Finally, we analyzed the transcriptomic data from heat‐treated and non‐heat‐treated R. × pulchrum plants to quantify the genes that are most important during heat stress in an effort to inform the development of climate‐resilient cultivars. This study provides insight into the genome diversity in Rhododendron and targets several genes related to agronomic traits that may help in further analysis. [ABSTRACT FROM AUTHOR]

Background: Development and persistence of multidrug resistant (MDR) bacteria is considered to be one of the biggest threats to public health worldwide. Development of new antimicrobial agents and alternatives to the conventional antimicrobial agents to control the menace of AMR is the need of the hour. Plants based products can be effectively explored as potential antimicrobial, antibiofilm and antiquorum sensing agents against major bacterial pathogens of human and animals. This present study was conducted to explore the antimicrobial, antibiofilm and antiquorum sensing activity of aqueous and methanol extracts of leaf, flower, fruit and stem of Melastoma malabathricum against clinical isolates of Staphylococcus aureus and Escherichia coli. Methods: E. coli and S. aureus were isolated and identified from diarrhoeic pigs and poultry and mastitic milk of cattle of Mizoram, respectively. Leaf, flower, fruit and stem of M. malabathricum were collected from Mizoram and extracted by methanol and aqueous solvents. The antimicrobial activity and MIC was determined by using well diffusion method and 96 wells microtiter plate method, respectively. Antibiofilm activity of plant extracts was determined in 96 well tissue culture plate. Antiquorum sensing activity was determined by disc diffusion method. Result: Methanol leaf extract exhibited antimicrobial activity against E. coli but not against S. aureus with 18 mm and 6 mm zone of inhibition at 200 mg/mL and 12.5 mg/mL, respectively. Methanol flower extract showed antimicrobial activity against S. aureus but not against E. coli with 14 mm and 6 mm zone of inhibitions at 200 mg/ml and 12.5 mg/mL, respectively. Similarly, the aqueous leaf extract showed antimicrobial activity against S. aureus but not against E. coli with 12 mm and 6 mm zone of inhibition at 200 mg/mL and 100 mg/mL, respectively. The MIC of M. malabathricum methanol leaf extract against E. coli was 3.125 mg/mL, whereas the MIC value of methanol flower and leaf extracts was 6.25 mg/mL against S. aureus. Antibiofilm activity of M. malabathricum methanol leaf, methanol flower and aqueous leaf extracts was recorded only against S. aureus isolates with maximum inhibition at 0.05 mg/mL concentration. Good antiquorum sensing activities was exhibited by the M. malabathricum methanol leaf, methanol flower and aqueous leaf extracts against S. aureus isolates at 200 mg/mL concentration. [ABSTRACT FROM AUTHOR]

Background: This work explored the characteristics of the WRKY transcription factor family in Rhododendron henanense subsp. lingbaoense (Rhl) and the expression patterns of these genes under abiotic stress by conducting bioinformatics and expression analyses. Methods: RhlWRKY genes were identified from a gene library of Rhl. Various aspects of these genes were analyzed, including genetic structures, conserved sequences, physicochemical properties, cis-acting elements, and chromosomal location. RNA-seq was employed to analyze gene expression in five different tissues of Rhl: roots, stems, leaves, flowers, and hypocotyls. Additionally, qRT-PCR was used to detect changes in the expression of five RhlWRKY genes under abiotic stress. Result: A total of 65 RhlWRKY genes were identified and categorized into three subfamilies based on their structural characteristics: Groups I, II, and III. Group II was further divided into five subtribes, with shared similar genetic structures and conserved motifs among members of the same subtribe. The physicochemical properties of these proteins varied, but the proteins are generally predicted to be hydrophilic. Most proteins are predicted to be in the cell nucleus, and distributed across 12 chromosomes. A total of 84 cis-acting elements were discovered, with many related to responses to biotic stress. Among the identified RhlWRKY genes, there were eight tandem duplicates and 97 segmental duplicates. The majority of duplicate gene pairs exhibited Ka/Ks values <1, indicating purification under environmental pressure. GO annotation analysis indicated that WRKY genes regulate biological processes and participate in a variety of molecular functions. Transcriptome data revealed varying expression levels of 66.15% of WRKY family genes in all five tissue types (roots, stems, leaves, flowers, and hypocotyls). Five RhlWRKY genes were selected for further characterization and there were changes in expression levels for these genes in response to various stresses. Conclusion: The analysis identified 65 RhlWRKY genes, among which the expression of WRKY_42 and WRKY_17 were mainly modulated by the drought and MeJA, and WRKY_19 was regulated by the low-temperature and high-salinity conditions. This insight into the potential functions of certain genes contributes to understanding the growth regulatory capabilities of Rhl. [ABSTRACT FROM AUTHOR]

The azalea (Rhododendron simsii Planch.) is an important ornamental woody plant with various medicinal properties due to its phytochemical compositions and components. However little information on the metabolite variation during flower development in Rhododendron has been provided. In our study, a comparative analysis of the flavonoid profile was performed in Rhododendron pulchrum sweet at three stages of flower development, bud (stage 1), partially open flower (stage 2), and full bloom (stage 3). A total of 199 flavonoids, including flavone, flavonol, flavone C-glycosides, flavanone, anthocyanin, and isoflavone were identified. In hierarchical clustering analysis (HCA) and principal component analysis (PCA), the accumulation of flavonoids displayed a clear development stage variation. During flower development, 78 differential accumulated metabolites (DAMs) were identified, and most were enriched to higher levels at the full bloom stage. A total of 11 DAMs including flavone (chrysin, chrysoeriol O-glucuronic acid, and chrysoeriol O-hexosyl-O-pentoside), isoflavone (biochanin A), and flavonol (3,7-di-O-methyl quercetin and isorhamnetin) were significantly altered at three stages. In particular, 3,7-di-O-methyl quercetin was the top increased metabolite during flower development. Furthermore, integrative analyses of metabolomic and transcriptomic were conducted, revealing that the contents of isoflavone, biochanin A, glycitin, and prunetin were correlated with the expression of 2-hydroxyisoflavanone dehydratase (HIDH), which provide insight into the regulatory mechanism that controls isoflavone biosynthesis in R. pulchrum. This study will provide a new reference for increasing desired metabolites effectively by more accurate or appropriate genetic engineering strategies. [ABSTRACT FROM AUTHOR]

Flower color is an important ornamental feature that is often modulated by the contents of flavonoids. Chalcone synthase is the first key enzyme in the biosynthesis of flavonoids, but little is known about the role of R. delavayi CHS in flavonoid biosynthesis. In this paper, three CHS genes (RdCHS1-3) were successfully cloned from R. delavayi flowers. According to multiple sequence alignment and a phylogenetic analysis, only RdCHS1 contained all the highly conserved and important residues, which was classified into the cluster of bona fide CHSs. RdCHS1 was then subjected to further functional analysis. Real-time PCR analysis revealed that the transcripts of RdCHS1 were the highest in the leaves and lowest in the roots; this did not match the anthocyanin accumulation patterns during flower development. Biochemical characterization displayed that RdCHS1 could catalyze p-coumaroyl-CoA and malonyl-CoA molecules to produce naringenin chalcone. The physiological function of RdCHS1 was checked in Arabidopsis mutants and tobacco, and the results showed that RdCHS1 transgenes could recover the color phenotypes of the tt4 mutant and caused the tobacco flower color to change from pink to dark pink through modulating the expressions of endogenous structural and regulatory genes in the tobacco. All these results demonstrate that RdCHS1 fulfills the function of a bona fide CHS and contributes to flavonoid biosynthesis in R. delavayi. [ABSTRACT FROM AUTHOR]

Based on a critical examination of type specimens, images of living plants, and the literature has shown Rhododendron oligocarpum to be conspecific with R. leishanicum. Although slight variations in corolla colour exist amongst different populations of R. oligocarpum, it does not serve as a key distinguishing trait. Therefore, we reduced R. oligocarpum to a synonym of R. leishanicum, and recommend placing it in Subsection Maculifera. [ABSTRACT FROM AUTHOR]

Rhododendron chrysanthum (R. chrysanthum) development is hampered by UV-B sunlight because it damages the photosynthetic system and encourages the buildup of carotenoids. Nevertheless, it is still unclear how R. chrysanthum repairs the photosynthetic system to encourage the formation of carotenoid pigments. The carotenoid and abscisic acid (ABA) concentrations of the R. chrysanthum were ascertained in this investigation. Following UV-B stress, the level of carotenoids was markedly increased, and there was a strong correlation between carotenoids and ABA. The modifications of R. chrysanthum's OJIP transient curves were examined in order to verify the regulatory effect of ABA on carotenoid accumulation. It was discovered that external application of ABA lessened the degree of damage on the donor side and lessened the damage caused by UV-B stress on R. chrysanthum. Additionally, integrated metabolomics and transcriptomics were used to examine the changes in differentially expressed genes (DEGs) and differential metabolites (DMs) in R. chrysanthum in order to have a better understanding of the role that ABA plays in carotenoid accumulation. The findings indicated that the majority of DEGs were connected to carotenoid accumulation and ABA signaling sensing. To sum up, we proposed a method for R. chrysanthum carotenoid accumulation. UV-B stress activates ABA production, which then interacts with transcription factors to limit photosynthesis and accumulate carotenoids, such as MYB-enhanced carotenoid biosynthesis. This study showed that R. chrysanthum's damage from UV-B exposure was lessened by carotenoid accumulation, and it also offered helpful suggestions for raising the carotenoid content of plants. [ABSTRACT FROM AUTHOR]

Infraspecific floral trait variations may appear in response to elevational differences in alpine plant species. There is enormous information on the selection of such morphs mediated by biotic and/or abiotic variables. Whether such differences contribute to differences in reproductive strategy and mating outcomes is rarely investigated. We investigated these aspects in two distinct elevational floral morphs (Red and Pink) of Rhododendron arboreum Sm. in Western Himalaya. The red morphs occupy the lower elevations while pink morphs the higher elevations. The two morphs differ in floral traits like phenology, dimension, display, quality of floral rewards, and pollinators that happen to influence interaction with available pollinator pool at each elevation. The pink morph exhibits entomophily, while the red ones show ornithophily. Although experimental pollinations established that both the morphs are selfcompatible, selfing results in significantly lower fruit-set than either cross-or open-pollinations. The outcrossing rate in the red morph, as determined by using simple sequence repeat (SSR) markers, was higher (tm=0.82) than that in the pink morph (tm=0.76), with a tendency of the latter to be shifting towards mixedmating strategy. However, the extent of biparental inbreeding was comparable among the two morphs. It is inferred that the differences in the mating outcomes among the morphs in the tree species are linked to those emerging from floral traits and the pollination by different functional groups of floral visitors. [ABSTRACT FROM AUTHOR]

Simple Summary: This experiment is based on the treatment of two forms of R. chrysanthum with UV-B radiation and transcriptomic and metabolomic analyses. It aims to explore how plants adapt to UV-B stress from metabolomic and transcriptomic perspectives. Through this comparative study, potential UV-B stress biomarker and UV-B-responsive metabolites were identified. The main concentration sites of some differentially expressed genes under UV-B stress were summarized. The metabolic synthesis pathway of R. chrysanthum under UV-B stress and the relationship network of key metabolite-related and synthetic enzymes were constructed. The experimental results show that domesticated R. chrysanthum has a stronger UV-B tolerance. By comparing the differences in response to UV-B stress between the two forms of R. chrysanthum, we provide a reference for breeding domesticated plants with UV-B tolerance characteristics. These results will help to study the complex mechanisms of plant adaptation to UV-B radiation. Rhododendron chrysanthum Pall. (R. chrysanthum), a plant with UV-B resistance mechanisms that can adapt to alpine environments, has gained attention as an important plant resource with the ability to cope with UV-B stress. In this experiment, R. chrysanthums derived from the same origin were migrated to different culture environments (artificial climate chamber and intelligent artificial incubator) to obtain two forms of R. chrysanthum. After UV-B irradiation, 404 metabolites and 93,034 unigenes were detected. Twenty-six of these different metabolites were classified as UV-B-responsive metabolites. Glyceric acid is used as a potential UV-B stress biomarker. The domesticated Rhododendron chrysanthum Pall. had high amino acid and SOD contents. The study shows that the domesticated Rhododendron chrysanthum Pall. has significant UV-B resistance. The transcriptomics results show that the trends of DEGs after UV-B radiation were similar for both forms of R. chrysanthum: cellular process and metabolic process accounted for a higher proportion in biological processes, cellular anatomical entity accounted for the highest proportion in the cellular component, and catalytic activity and binding accounted for the highest proportion in the molecular function category. Through comparative study, the forms of metabolites resistant to UV-B stress in plants can be reflected, and UV-B radiation absorption complexes can be screened for application in future specific practices. Moreover, by comparing the differences in response to UV-B stress between the two forms of R. chrysanthum, references can be provided for cultivating domesticated plants with UV-B stress resistance characteristics. Research on the complex mechanism of plant adaptation to UV-B will be aided by these results. [ABSTRACT FROM AUTHOR]

With the rapid advancement of the global economy, there has been a noticeable escalation in the level of inhalable particulate matter (PM) pollution in the atmosphere. The utilization of plants has been recognized as an effective means to mitigate the escalation in the atmospheric PM concentration through the capture and retention of this particulate matter on their leaves. This research focuses on investigating the PM retention capacity of nine commonly found greening plant species in Changsha, China, located in the country's mid-subtropical region. In this study, we employed an air aerosol generator (QRJZFSQ-II) and a portable leaf area meter (LI-3000C) to systematically evaluate the PM retention in unit leaf area for different PM values. In addition, the leaf surface structure was observed via scanning electron microscopy, and the relationship between the leaf microstructure and the retained particles was quantitatively analyzed. The results showed that (1) there were significant differences in the retention of TSP, PM10, and PM2.5 per unit leaf area among the nine greening tree species analyzed. Rosa saturata was found to have the best retention effect regarding TSP and PM2.5, and Rhododendron simsii was found to have the best retention effect regarding PM10. (2) There were significant differences in the contents of TSP and PM2.5 per leaf area among the different tree species with different life forms (p < 0.05), with the order of retention being shrub > arbor (needle leaves) > arbor (broad leaves). (3) Coniferous plants have a deep leaf surface texture, which is conducive to capturing more particles on their leaf surface, and (4) the long stomata diameter was significantly negatively correlated with PM retention, and the stomata density was significantly positively correlated with PM retention. However, the short diameter and small area of stomata demonstrated no significant correlation with PM retention (p < 0.05). Considering the selection of suitable tree species for greening in urban air pollution control, we suggest that Osmanthus fragrans, Pseudolarix amabilis, Rosa saturata, and Rhododendron simsii be used more frequently in urban areas affected by severe air pollution. [ABSTRACT FROM AUTHOR]

To explore the population structures and dynamics of Rhododendron shrub communities at different stages of succession in northwest Guizhou, China, this study examined the populations of Rhododendron annae and Rhododendron irroratum shrub with two different stages. A space-for-time substitution was employed to establish the diameter class/height structures, static life tables, and survival/mortality rate/disappearance rate curves of both Rhododendron populations with different orders of succession. Their structural and quantitative dynamics were analyzed, and their development trends were predicted. The results showed that, quantitatively, the populations of R. annae and R. irroratum in the two Rhododendron communities with different orders of succession were dominated by age classes one, two, and three as well as height classes i, ii, and iii. The number of Rhododendron plants at the three age classes and the three height classes accounted for 97.61–100% of the total. The quantitative dynamic indices of R. annae and R. irroratum were both greater than 0, with and without considering external interference. In terms of age class and height structures, both Rhododendron populations were expanding populations, presenting "inverted-J-shaped" and irregular pyramid patterns. There was a sufficient number of young individuals, but few or no old individuals. Both survival curves of the populations of R. annae and R. irroratum in the two Rhododendron communities with different orders of succession belonged to the Deevy-II type. In the late stage of succession, the mortality curves and disappearance curves of both Rhododendron populations in these communities presented a trend of increasing first and then decreasing with increasing age class. This result indicates that at each age class, R. annae and R. irroratum showed a trend of gradual increase after two, four, and six years. In brief, the populations of R. annae and R. irroratum have rich reserves of seedlings and saplings, but high mortality and disappearance rates. In this context, it is necessary to reduce human interference and implement targeted conservation measures to promote the natural renewal of Rhododendron populations. [ABSTRACT FROM AUTHOR]