RAD-seq data reveals robust phylogeny and morphological evolutionary history of Rhododendron

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(cladeⅠ)formed the basal lineage.Subg.Tsutsusi and Azaleastrum formed cladeⅡand had sister relationships.CladeⅢincluded all scaly rhododendron species.Subg.Pentanthera(cladeⅣ)formed a sister group to Subg.Hymenanthes(cladeⅤ).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.

Projecting the potential distribution and analyzing the bioclimatic factors of four Rhododendron subsect.Tsutsusi species under climate warming

Tsutsusi is one of the eight subgenera of the Rhododendron genus.Four Tsutsusi species,R.indicum,R.simisii,R.oldhamii,and R.schlippenbachii,have high ornamental and medicinal values,resulting in an increasing market demand.These species thrive in cool and humid environments and are widely distributed in Europe and Asia.Whether global climate warming will affect the distribution of these valuable resources remains unclear.Thus,this study analyzed the climatic suitability of these species for the first time on the basis of 1552 geographical distribution points and 19 bioclimatic factors using the maximum entropy model.The results show that a suitable distribution area for all four species would decrease under climate warming.The main bioclimatic factors affecting their distribution are the mean temperature of the coldest quarter for R.indicum,the mean diurnal range for R.simisii,and precipitation of the warmest quarter for R.oldhamii and R.schlippenbachii.In addition,the contribution of the temperature-related bioclimatic factors to the distribution of R.indicum and R.simisii is higher than that of the associated precipitation-related climatic factors;in contrast,the contribution of precipitation-related bioclimatic factors to the distribution of R.oldhamii and R.schlippenbachii is higher than that of the temperature-related climatic factors.These results provide references for the introduction,conservation,sustainable development,and utilization of these four species in the future,and may also provide information with regards to other Rhododendron species.

Structural characterization of four Rhododendron spp.chloroplast genomes and comparative analyses with other azaleas

Azalea is a general designation of Rhododendron in the Ericaceae family.Rhododendron not only has high ornamental value but also has application value in ecological protection,medicine,and scientific research.In this study,we used Illumina and PacBio sequencing to assemble and annotate the entire chloroplast genomes(cp genomes)of four Rhododendron species.The chloroplast genomes of R.concinnum,R.henanense subsp.lingbaoense,R.micranthum,and R.simsii were assembled into 207,236,208,015,207,233,and 206,912 bp,respectively.All chloroplast genomes contain eight rRNA genes,with either 88 or 89 protein-coding genes.The four cp genomes were compared and analyzed by bioinformatics,and the phylogenetic analysis based on chloroplast genomes of 26 species of Ericaceae,Actinidiaceae,and Primulaceae under Ericales was conducted.A comparison of the linear structure of cp genomes of four Rhododendron showed that there were substantial sequence similarities in coding regions,but high differences in non-coding regions.A phylogenetic analysis,based on chloroplast whole genome sequences,showed that all Rhododendron species are in the clade Ericaceae.This study provides valuable genetic information for the study of population genetics and evolutionary relationships in Rhododendron and other azalea species.

Ecosystem Service Value Assessment of Wutong Mountain Rhododendron moulmainense Ecological Landscape Forest in Shenzhen City in 2021

Taking Wutong Mountain Rhododendron moulmainense ecological landscape forest in Shenzhen City as an example,the value of the forest was assessed by constructing an ecological service value assessment system and accounting method.The assessment results showed that the total ecosystem service value of R.moulmainense ecological landscape forest was 13.195 billion yuan,and the top three services included the value of forestry products,the value of biodiversity maintenance and the value of leisure and recreation,indicating that the ecosystem service of Wutong Mountain R.moulmainense ecological landscape forest in Shenzhen has great ecological and economic value,especially in forestry products,biodiversity maintenance,and leisure and recreation.

Two New Compounds from Rhododendron Przewalskii Maxim

Two new ionone derivatives, rhododendrone A and rhododendronside, have been isolated from the alcoholic extract of the aerial parts of Rhododendron Przewalskii Maxim . The structures of the two compounds, (3R,6S) -3-hydroxy- α -ionone 1 and 1,1,5-trimethyl-6-(3-hydroxyl)cyclohexene-5-yl-1- β-D -pyranoglucoside 2, have been elucidated on the basis of the spectroscopic analyses.

Two New Ionone Derivatives from Rhododendron przewalskii Maxim.

Two new ionone derivatives, named rhododendrone and rhododendronside, were isolated from the alcoholic extract of the aerial parts of Rhododendron przwalskii Maxim. Their structures were elucidated on the basis of spectroscopic analysis

Rhododendron dauricum的木材解剖学研究

Rhododendron dauricum是 Ericaceae,Rhododendron植物 ,对其木材进行解剖发现其为散孔材 ,射线为异 型 ,在离析材料可见维管管胞和纤维管胞 。

Genetic diversity and structure of Rhododendron meddianum,a plant species with extremely small populations

Rhododendron meddianum is a critically endangered species with important ornamental value and is also a plant species with extremely small populations.In this study,we used double digest restriction-siteassociated DNA sequencing(ddRAD)technology to assess the genetic diversity,genetic structure and demographic history of the three extant populations of R.meddianum.Analysis of SNPs indicated that R.meddianum populations have a high genetic diversity(p?0.0772±0.0024,HE?0.0742±0.002).Both FST values(0.1582e0.2388)and AMOVA showed a moderate genetic differentiation among the R.meddianum populations.Meanwhile,STRUCTURE,PCoA and NJ trees indicated that the R.meddianum samples were clustered into three distinct genetic groups.Using the stairway plot,we found that R.meddianum underwent a population bottleneck about 70,000 years ago.Furthermore,demographic models of R.meddianum and its relative,Rhododendron cyanocarpum,revealed that these species diverged about 3.05(2.21e5.03)million years ago.This divergence may have been caused by environmental changes that occurred after the late Pliocene,e.g.,the Asian winter monsoon intensified,leading to a drier climate.Based on these findings,we recommend that R.meddianum be conserved through in situ,ex situ approaches and that its seeds be collected for germplasm.

Pollen morphology of Rhododendron subgen. Tsutsusi and its systematic implications

Eighty-four pollen samples were obtained for 80 taxa, of which, 13 species and one variety are from sect. Brachycalyx Sweet, 58 species and two varieties from sect. Tsutsusi Sweet, and six species from subgen. Pentanthera （G. Don） Pojarkova, respectively. Pollen morphology of all samples was observed using LM and SEM. Pollen grains are revealed to be spheroidal and tetrahedral with tricolporate apertures. Pollen sizes of subgen. Tsutsusi （Sweet） Pojarkova range from 37.67 μm to 61.06μm, and the exine sculptures are more or less compactly granulated. Pollen sizes are significantly different between sect. Brachycalyx and sect. Tsutsusi of subgen. Tsutsusi. Rhododendron tashiroi Maxim. of sect. Tsusiopsis Sleumer shows a close affinity to sect. Brachycalyx. Pollen size and exine are consistent with general morphology in differentiating species in sect. Tsutsusi. Rhododendron huadingense B. Y. Ding ＆ Y. Y. Fang, once placed as a member of sect. Brachycalyx, should be considered as a species in subgen. Pentanthera.

Studies on the Chemical Constituents of the Roots of Rhododendron Molle G. Don

The compounds from the root of Rhododendron molle G.Don were isolated, purified by various chromatographic techniques, and their structures were identified according to the physical and chemical features and spectral data. Three compounds were separated from the root of Rhododendron molle G.Don and identified as Rhodojaponin-Ⅲ, taraxerol, β-sitosterol for the first time.

Multiple Spatial Scale Analysis of the Niche Characteristics of the Rhododendron dauricum Plant Communities in Northeast China

This study aims to verify the concept of niches at multiple spatial scales in plant communities.To this end,we analyzed the niche characteristic of Rhododendron dauricum plant communities in Northeast China at three spatial scales.At the local scale,we calculated the Importance Value(IV)of species in five communities in the north of the Da Hinggan Mountains.At the intermediate scale,we examined five communities in their entirety,calculated the niche breadth of the species,and integrated niche overlap and interspecific association to analyze interspecific relationships.Further,the generalized additive model(GAM)was used to analyze the impact of topography and soil factors on niche characteristics.At the regional scale,we analyzed the geographical distribution of dominant species of R.dauricum plant communities in Northeast China and used principal component analysis(PCA)to analyze the impact of geographical and climate factors on species distribution.The results show that at the local scale,the IV of the species in each community varies widely.At the intermediate scale,species with a wide niche breadth tend to have a high value for IV.Larix gmelinii,Betula platyphylla,R.dauricum,Ledum palustre,and Vaccinium vitis-idaea had a relatively wide niche breadth and a high niche overlap,and the interspecific associations were almost all positive.Elevation and soil nutrients were the most dominant environmental factors.At the regional scale,species with a wide niche breadth tend to have a wide range of distribution,and temperature and precipitation were the most dominant environmental factors.This study suggests that the niche characteristics at three scales are both related and different.Niche characteristics at the local scale were various and labile,and niche characteristics at the intermediate and regional scales were relatively regular.These results show some degree of consistency with previous studies from an evolutionary perspective.The action mechanisms of these communities are related to differences in the dominant environmental factors.In addition,the integration of niche overlap and interspecific association determine interspecific relationships more accurately.

One New Diterpene Glucoside from the Roots of Rhododendron molle

One new grayanane diterpene glucoside, rhodomoside A 1 was isolated from the roots of Rhododendron molle G. Don (Ericaceae). Its structure was elucidated on the basis of spectral analysis.

Phenolic Components from Rhododendron latoucheae Part 5 in the series "Chemical Studies on Ericaceae Plants

From the leaves of Rhododendron latoucheae (Ericaceae), two new natural phenolic compounds named (+)-rhodolatouchol 1 and isoepirhododendrin 4 were identified. Six other known compounds, (+)-rhododendrol, epirhododendrin, 4-[3'-O-beta-D-glucopyranosyl-4'-hydroxyphenyl]-2-butanone, 4-(4'-O-beta-D-glucopyranosylphenyl)-2-butanone, benzyl-O-beta-D-glucopyranoside and arbutin were also obtained.

Comparative population genetic analyses suggest hybrid origin of Rhododendron pubicostatum,an endangered plant species with extremely small populations endemic to Yunnan,China

Gene flow between sympatric congeneric plants is thought to be very common and may pose serious threats to endangered species.In the present study,we evaluate the genetic diversity and divergence of three sympatric Rhododendron species in Jiaozi Mountain using newly developed microsatellites through the Illumina MiSeq sequencing approach.Genetic diversity of all three Rhododendron species studied was moderate in comparison to genetic parameters previously reported from species of this genus.Interestingly,genetic structure analysis of the three species identified a possible hybrid origin of the threatened Rh.pubicostatum.This sympatry should be considered a unimodal hybrid zone,since Rh.pubicostatum is predominant here.Unimodal hybrid zones are uncommon in Rhododendron,despite the fact that hybridization frequently occurs in the genus.Issues pertaining to the conservation of Rh.pubicostatum resulting from admixture of genetic material from its parental species are discussed.

Induction and characterization of polyploids from seeds of Rhododendron fortunei Lindl.

Most Rhododendron species are ornamental flowering species widely distributed in Asia,North America,and West Europe.Rhododendron fortunei,one of the endemic Rhododendron species in China,has beautiful flowers with bright colors and is being exploited to meet the needs of the flower market.Polyploid plants usually show superiority in growth,disease resistance,and adaption over their diploid relatives.Here,we report the first case of polyploid induction in R.fortunei.In order to induce polyploidy in R.fortunei,germinating seeds were treated with different concentrations of oryzalin for 16 h.By evaluating ploidy level with flow cytometry,a total of 34 polyploid R.fortunei lines,including 27 tetraploid lines and seven octoploid lines,were obtained.A comparison of treatments indicated that 7.5 mg L^-1 oryzalin was the optimal concentration for polyploid induction in seeds of R.fortunei.Compared with diploid plants,tetraploid and octoploid plants exhibited slower growth rates and had thicker and rounder curled leaves with more leaf epidermal hairs.Moreover,larger stomata at lower density were also observed in the leaves of polyploid plants.Chlorophyll contents were also significantly increased in polyploid plants,which leads to a darker green leaf color.Both small and large individuals exhibiting the same characteristics were observed among the obtained tetraploid plants.Overall,our study establishes a feasible method for polyploid induction in R.fortunei,thus providing a basis for breeding new R.fortunei varieties.

Adaptability of Rhododendrons in high altitude habitats

Tree species dominate many ecosystems throughout the world and their response to climate,in light of global warming,is a matter of primary concern.This review describes past and ongoing research in Rhododendron,an ecologically important and well-adapted genus of more than 1000 species,occupying diverse habitats.Research to date indicates survival ability and mechanisms,with an emphasis on cold tolerance.The capability of longdistance gene flow in these species increases their genetic variability which in turn enhances their adaptability to newer niches as well as to environmental gradients(mainly temperature).Attempts to explain the molecular basis of morphological and behavioural changes in Rhododendron against cold-induced damage has been made.Gradual advances in‘omics’have led to an enriched genomic resource dissecting the role and interaction of multiple molecular factors participating in cold adaptability.However,fewer genetic studies are available on species with an inherent or a default cold-tolerance ability.Considering this fact,understanding specific features of an adapted species can provide insights on overriding the effects of desiccation and determining phase transitions in other plants as well.We propose to integrate ecological and evolutionary studies with functional genomics to improve predictions of tree responses to their environment.

Diversity of root-associated fungi of Rhododendron simsii in subtropical forests: fungal communities with high resistance to anthropogenic disturbances

Species of the Ericaceae or heath family are widely distribute in continental ecosystems and their special ericoid mycorrhizas(ERM)are considered benefi cial to their survival and persistence in variable habitats.Currently,increasing anthropogenic disturbances and improper forest management are aff ecting subtropical forests of China where these native species located.These activities not only aff ect plant communities above-ground,but also impose pressures on microbial communities below-ground.In this study,rootassociated fungal communities of Rhododendron simsii in four forest types under diff erent anthropogenic disturbances were identifi ed using an Illumina Miseq platform,i.e.,old growth forests,secondary forests with one cutting(SECⅠ),secondary forests with two cuttings(SECⅡ),and Chinesefi r plantations(PLF).Intra-and inter-annual variations were analyzed by comparing samples taken in diff erent seasons and years.The results show that:(1)over 1000 OTUs were found in hair roots with most from the division Ascomycota and Basidiomycota belonging to diff erent functional groups;(2)while there were a few indicator OTUs specifi c to diff erent forest types,seasons and years,the proportion of shared taxa was quite large,accounting for 44.9–79.4%of the total OTUs;(3)signifi cantly positive correlations were found between disturbance sensitivity and temporal variations in common fungal orders,and both in major fungal orders were signifi cantly diff erent among fungal functional groups in which putative and possible ERM fungi were highly resistant to disturbances and low temporal variations.The high disturbance resistance and temporal persistence of putative ERM fungi may be essential for the successful adaptation of R.simsii in disturbed subtropical forests of China.

Antihyperglycemic and antihyperlipidemic activity of ethyl acetate fraction of Rhododendron arboreum Smith flowers in streptozotocin induced diabetic rats and its role in regulating carbohydrate metabolism

Objective:To explore and identify the most potent antihyperglycemic fraction from the ethanol extract of Rhododendron arboreum(R.arboreum)flowers.Methods:Normal and streptozotocin induced diabetic rats were treated with all four fractions of R.arboreum flowers for short term and with fraction 3 for long term study.On completion of the treatment,a range of indicators were tested including fasting blood glucose,plasma protein,haemoglobin A1C,insulin secretion,body weight,blood lipid profile and carbohydrate metabolism regulating enzymes of liver.Results:In short term study,the fraction 3(Active fraction)produced a significant(P<0.0001)reduction(73.6%)in blood glucose level at a dose of 200 mg/kg after the treatment in the diabetic rats.Administration of active fraction(200 and 400 mg/kg)once daily for 30 d in streptozotocin diabetic rats resulted in a significant(P<0.001 to P<0.0001)fall in blood glucose level,hemoglobin A1C,serum urea and creatinine with significant but a increase in insulin level similar to standard drug glybenclamide.Further,the active fraction showed antihyperlipidemic activity as evidenced by significant(P<0.001 to P<0.0001)decreases in serum serum total cholesterol,triglycerides,low density lipoprotein cholesterol and very low density cholesterol levels coupled together with elevation of high density lipoprotein cholesterol in the diabetic rats.Conclusions:The active fraction of R.arboreum flowers decreases streptozotocin induced hyperglycemia by promoting insulin secretion and glycolysis and by decreasing gluconeogenesis.

Two New Phenolic Glycosides from the Roots of Rhododendron molle

Two new phenolic glycosides, everninic acid methyl ester-2-O-b-D- xylopyran- osyl-(16)-b-D-glucopyranoside 1 and 7-hydroxy-5-methoxyphthalide-7-b-D- xylopyranosyl- (16)-b-D-glucopyranoside 2 were isolated from the roots of Rhododendron molle G. Don. Their structures were determined by spectral evidence including 2D NMR techniques.

Rhododendron kuomeianum(Ericaceae),a new species from northeastern Yunnan(China),based on morphological and genomic data

Rhododendron kuomeianum Y.H.Chang,J.Nielsen&Y.P.Ma,a new species of Rhododendron(Ericaceae)within subsect.Maddenia in sect.Rhododendron from Yiliang County,NE Yunnan,China,is described and illustrated.The new species is similar to R.valentinianum,but it can be easily distinguished by its sparse scales on the abaxial surface of the leaf blade,fewer flowers per inflorescence and white corolla with pale red margins.There are also differences in the widths of calyx lobes,leaf blade shape and indumentum characteristics of the petiole between the new species and Rhododendron linearilobum.We confirmed that R.kuomeianum is a new species closely related to R.valentinianum and R.changii with phylogenomic studies of 10 species within this subsection based on restriction site-associated DNA sequencing(RADseq)data.These phylogenomic analyses also clarified additional taxonomic problems in this subsection previously raised by morphological analysis.Our findings make a strong case for using next-generation sequencing to explore phylogenetic relationships and identify new species,especially in plants groups with complicated taxonomic problems.