Deciphering complex reticulate evolution of Asian Buddleja (Scrophulariaceae): insights into the taxonomy and speciation of polyploid taxa in the Sino-Himalayan region.

BACKGROUND AND AIMS: Species of the genus Buddleja in Asia are mainly distributed in the Sino-Himalayan region and form a challenging taxonomic group, with extensive hybridization and polyploidization. A phylogenetic approach to unravelling the history of reticulation in this lineage will deepen our understanding of the speciation in biodiversity hotspots. METHODS: For this study, we obtained 80 accessions representing all the species in the Asian Buddleja clade, and the ploidy level of each taxon was determined by flow cytometry analyses. Whole plastid genomes, nuclear ribosomal DNA, single nucleotide polymorphisms and a large number of low-copy nuclear genes assembled from genome skimming data were used to investigate the reticulate evolutionary history of Asian Buddleja. Complex cytonuclear conflicts were detected through a comparison of plastid and species trees. Gene tree incongruence was also analysed to detect any reticulate events in the history of this lineage. KEY RESULTS: Six hybridization events were detected, which are able to explain the cytonuclear conflict in Asian Buddleja. Furthermore, PhyloNet analysis combining species ploidy data indicated several allopolyploid speciation events. A strongly supported species tree inferred from a large number of low-copy nuclear genes not only corrected some earlier misinterpretations, but also indicated that there are many Asian Buddleja species that have been lumped mistakenly. Divergent time estimation shows two periods of rapid diversification (8-10 and 0-3 Mya) in the Asian Buddleja clade, which might coincide with the final uplift of the Hengduan Mountains and Quaternary climate fluctuations, respectively. CONCLUSIONS: This study presents a well-supported phylogenetic backbone for the Asian Buddleja species, elucidates their complex and reticulate evolutionary history and suggests that tectonic activity, climate fluctuations, polyploidization and hybridization together promoted the diversification of this lineage.

Chemical investigation of Buddleja officinalis leaves and localization of defensive triterpenoids to its glandular trichomes.

Buddleja officinalis is a traditional Chinese medicinal plant covered with glandular and non-glandular trichomes on leaves. Phytochemical investigation of its leaves led to the identification of one undescribed tetranorcycloartane 3-oxo-25,26,27,29-tetranorcycloartan-24-oic acid (1) and one first identified natural product tetranorcycloartane 3-oxo-25,26,27,29-tetranorcycloartan-24-oic methyl ester (2), along with an undescribed megastigmane glucoside (3) and 14 known constituents (4-17). Structures of undescribed chemicals were elucidated by comprehensive 1D and 2D NMR, MS and CD analysis. Further chemical investigation resulted in six triterpenoids (4-9) being localized to the trichomes of B. officinalis. The major trichome components cycloeucalenone (4) and 24-oxo-29-norcycloartan-3-one (5) showed potent antifeedant activity against a generalist insect cotton bollworm (Helicoverpa armigera), but no obvious activity against the specialist herbivore Hyphasis inconstans. Compounds 4 and 7 also displayed inhibitory effects on seed germination of Arabidopsis thaliana. In addition, 1 and 4 exhibited moderate antibacterial activity toward three gram-positive bacteria.

Extraction and Purification of Flavonoids from Buddleja officinalis Maxim and Their Attenuation of H2O2-Induced Cell Injury by Modulating Oxidative Stress and Autophagy.

Cataracts are an ailment representing the leading cause of blindness in the world. The pathogenesis of cataracts is not clear, and there is no effective treatment. An increasing amount of evidence shows that oxidative stress and autophagy in lens epithelial cells play a key role in the occurrence and development of cataracts. Buddleja officinalis Maxim flavonoids (BMF) are natural antioxidants and regulators that present anti-inflammatory and anti-tumor effects, among others. In this study, we optimized the extraction method of BMFs and detected three of their main active monomers (luteolin, apigenin, and acacetin). In addition, a model of oxidative damage model using rabbit lens epithelial cells induced by hydrogen peroxide (H2O2). By detecting the levels of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), malondialdehyde (MDA), and OH (OH), the expression of autophagosomes and autolysosomes were observed after MRFP-GFP-LC3 adenovirus was introduced into the cells. Western blotting was used to detect the expression of Beclin-1 and P62. Our research results showed that the optimal extraction parameters to obtain the highest yield of total flavonoids were a liquid−solid ratio of 1:31 g/mL, an ethanol volume fraction of 67%, an extraction time of 2.6 h, and an extraction temperature of 58 °C. Moreover, the content of luteolin was 690.85 ppb, that of apigenin was 114.91 ppb, and the content of acacetin was 5.617 ppb. After oxidative damage was induced by H2O2, the cell survival rate decreased significantly. BMFs could increase the levels of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) and decrease the levels of malondialdehyde (MDA) and OH (OH). After the MRFP-GFP-LC3 virus was introduced into rabbit lens epithelial cells and detecting the expression of P62 and Beclin-1, we found that the intervention of BMF could promote the binding of autophagosomes to lysosomes. Compared with the model group, the level of P62 in the low-, middle-, and high-dose groups of BMF was significantly down-regulated, the level of Beclin-1 was significantly increased, and the difference was statistically significant (p < 0.05). In other words, the optimized extraction method was better than others, and the purified BMF contained three main active monomers (luteolin, apigenin, and acacetin). In addition, BMFs could ameliorate the H2O2-induced oxidative damage to rabbit lens cells by promoting autophagy and regulating the level of antioxidation.

[A new sesquiterpene from stems of Buddleja lindleyana].

The present study investigated the chemical constituents from the stems of Buddleja lindleyana. Ten compounds were isolated from the 95% EtOH extract of B. lindleyana stems by means of some techniques including polyamide, silica gel, MCI, Sephadex LH-20 column chromatography, and semi-preparative high-performance liquid chromatography(HPLC). Their structures were identified by spectral analysis and single-crystal X-ray diffraction as buddledin F(1), 6-O-4″-hydroxy-3″-methoxy-benzoyl ajugol(2), negundoin G(3),(+)-dihydrocubebin(4), 7-O-ethylguaiacylglycerol(5),(-)-jatrointelignan B(6), threo-1,2-bis-(4-hydroxy-3-methoxyphenyl)-propane-1,3-diol(7), vomifoliol(8), hinokinin(9), and isovanillic acid(10). Compound 1 was a new sesquiterpene named buddledin F. Compounds 3-8 were isolated from the Buddleja plant for the first time. The anti-inflammatory activities of compounds 1-10 in vitro were investigated, and the results failed to show the inhibitory activities of these compounds on the production of inflammatory factor NO.

Acidic polysaccharides from Buddleja officinalis inhibit angiogenesis via the Nrf2/ARE pathway to attenuate diabetic retinopathy.

The purpose of this study was to verify that acid polysaccharides from Buddleja officinalis Maxim (APBOM) could relieve diabetic retinopathy (DR) through inhibition of angiogenesis via activation of the Nrf2/ARE signaling pathway. Transgenic db/db mice were used to establish a DR model, and it was found that APBOM could improve levels of blood glucose, blood lipids and insulin, and further improve pathological retinal tissue structure as well as vascular network structure. Moreover, APBOM could lessen the amount of angiogenesis by reducing the expression of CD34 and VEGF, and then delay the development process of DR. In in vitro mechanistic experiments, the generation of ROS was inhibited after APBOM intervention, and the expression of CD34, CD31 and VEGF was decreased. Furthermore, the mRNA and protein levels of HO-1, NQO1, SOD and Nrf2 were increased, which indicated that APBOM might promote expression of the Nrf2/ARE signaling pathway. Overall, APBOM might alleviate DR by inhibiting angiogenesis and activating the Nrf2/ARE signaling pathway.

A Novel Fluorescent Dye Extracted from Buddleja officinalis for Labeling Mitochondria after Fixation.

Mitochondria are versatile organelles and function by communicating with cellular ecosystems. The fluorescent colocalization analysis after fixation is a highly intuitive method to understand the role of mitochondria. However, there are few fluorescent dyes available for mitochondrial staining after fixation. In this study, a novel fluorescent dye (BO-dye), extracted from Buddleja officinalis, was applied for mitochondrial staining in fixed immortalized human oral keratinocytes. The BO-dye (excitation: 414 nm, emission: 677 nm) is a small fluorescent molecular dye, which can cross the cytomembrane without permeabilization. We assume that the BO-dye could aggregate and bind to the mitochondria stably. BO-dye exhibited a mega-Stokes shift (>250 nm), which is an important feature that could reduce self-quenching and enhance the signal-to-noise ratio. Analysis of photophysical properties revealed that the BO-dye is temperature and pH insensitive, and it exhibits superior photostability. These results indicate that BO-dye can be considered an alternative fluorescent dye for labeling mitochondria after fixation.

Antioxidant and anti-inflammatory polyphenols in ultrasound-assisted extracts from salvilla (Buddleja scordioides Kunth).

Salvilla is a widely distributed plant used in treatments against gastrointestinal disorders due to its phenolic antioxidant and anti-inflammatory potential. Major yield and quality of bioactive polyphenols must be obtained with no degradation during suitable processes such as Ultrasound-Assisted Extraction (UAE), which allows an efficient extraction of metabolites at appropriate parameter conditions. Salvilla extractions were made using UAE and aqueous ethanolic solutions. Variables used in UAE were sonication time, wave amplitude and percentage of ethanol in solvent. Extracts were tested for total flavonoids, antioxidant activity (ABTS, FRAP and ORAC) and an identification and quantification of phenolic compounds was carried out by UPLC-PDA-ESI-MS/MS. Once elected the better extraction conditions, an anti-inflammatory test was performed for this treatment. As a result, total flavonoids content in extracts was 147 to 288 µg catechin equivalents/mg of dry salvilla extract. All extracts have shown good antioxidant activity (86 to 280 mM Trolox eq/mg dry salvilla extract). Flavonoids contents by chromatography were higher than hydroxybenzoic and hydroxycinnamic acids specially the flavone, flavanol and flavanone groups. Treatment T6 (75% ethanol, 30% amplitude and 10 min extraction time) was the best extract in terms of significant flavonols, antioxidant activity, and higher anti-inflammatory potential.

Anti-inflammatory and anti-arthritic effects of compounds from Buddleja coriacea.

Buddleja coriacea (B. coriacea) commonly known as 'Kiswara' is used as infusions for stomach and joint pain. This study aims to evaluate the in vitro and in vivo anti-inflammatory and anti-arthritic activity was evaluated by measuring inflammatory parameters (TNF-α, C-reactive protein and Fibrinogen) in murine models of the aqueous extract and isolated compounds of B. coriacea. A bio-guided phytochemical analysis based on NMR/MS was performed identifying three (1-3) compounds of the aqueous extract. All compounds inhibited the production of TNF-α in RAW 264.7 cell line, with IC50 of 13.44 (1), 1.13 (2) and 0.57 µM (3), respectively. In addition, compounds 2 and 3 decreased the levels of TNF-α, C-reactive protein and fibrinogen at a concentration of 5 mg/kg in murine models. Our research shows that the compounds isolated from B. coriacea have anti-inflammatory and anti-arthritic properties, providing scientific evidence for the traditional use of this plant species.

A new diterpene and bioactivities of labdanes isolated from Buddleja marrubiifolia.

The new labdane [(3R*,4aR*,7S*,10aS*,10bR*)-3-ethenyl-3,4a,7,10a-tetramethyl-dodecahydro-1H-naphtho-[2,1-b]-pyran-7-yl]-methylbenzoate together with other 7 labdanes were isolated from the aerial parts of Buddleja marrubiifolia. Compound structures were elucidated by spectroscopic methods. Some compounds showed moderate to weak antimicrobial activity towards a panel of bacterial and fungal pathogens. In addition, trans-biformene (2) and ribenol acetate (8) showed to be highly cytotoxic with LC50 < 1 µg/mL, the other compounds showed moderate cytotoxic effect with a LC50 range of 6.008-15.26 µg/mL. For all isolated compounds, no inflammatory response was observed.

Characterization of the Complete Chloroplast Genome of Buddleja lindleyana.

BACKGROUND: Buddleja lindleyana Fort., which belongs to the Loganiaceae with a distribution throughout the tropics, is widely used as an ornamental plant in China. There are several morphologically similar species in the genus Buddleja, but the lack of comprehensive molecular and phylogenetic studies makes it difficult to distinguish related species, which hinders further studies of this genus. OBJECTIVE: Using molecular biology techniques to sequence and analyze the complete chloroplast (cp) genome of B. lindleyana. METHODS: After sequencing of the genomic DNA using next-generation sequencing, a series of bioinformatics software were used to assemble and analyze the molecular structure of the cp genome of B. lindleyana. RESULTS: The complete cp genome of B. lindleyana is a circular 154 487-bp-long molecule with a GC (Guanine and Cytosine) content of 38.1%. It has a quadripartite structure, including a LSC region (85 489 base pair (bp)), a small single-copy region (17 898 bp), and a pair of inverted repeat regions (25 550 bp). A total of 133 genes were identified in this genome, including 86 protein-coding genes, 37 tRNA (transfer Ribonucleic Acid) genes, eight rRNA (ribosomal Ribonucleic Acid) genes, and two pseudogenes. CONCLUSION: These results suggest that the B. lindelyana cp genome could be used as a potential genomic resource to resolve the phylogenetic positions and relationships of Loganiaceae, and will offer valuable information for future research in the identification of Buddleja species and will conduce to genomic investigations into these species. HIGHLIGHTS: This paper study the B. lindelyana cp genome and it's structural characteristics, and analyze the phylogeny of Loganiaceae.

Glycosides from Buddleja officinalis with their protective effects on photoreceptor cells in light-damaged mouse retinas.

A new phenylethanoid, hebitol IV (1), along with fifteen known glycosides (2-16), were isolated from water extract of the flower buds of Buddleja officinalis. Their structures were elucidated on the basis of 1 D-NMR, 2 D-NMR and MS data. Molecular docking showed the potential activities of the natural products against VEGFR-2. Bioassay results revealed that the compounds 10 and 14 exhibited strong inhibitory activity against VEGFR-2 with IC50 values of 0.51 and 0.32 µM, respectively. Moreover, the potential retinal protective effects of 10 and 14 were then investigated in the mouse model featuring bright light-induced retinal degeneration. The results demonstrated remarkable photoreceptor protective activities of 10 and 14 in vivo.

Anti-inflammatory and antioxidant activities of chemical constituents from the flower buds of Buddleja officinalis.

Five new glycosides including mimenghuasu A and B (1-2), isolinarin (3), cyclocitralosides A and B (4-5), along with forty-seven known compounds were isolated from the flower buds of Buddleja officinalis. These structures were elucidated by extensive spectroscopic analysis (UV, IR, 1 D, 2 D NMR, and MS spectra). The anti-inflammatory activities of the isolated compounds were determined by enzyme-linked immunosorbent assay (ELISA) on the expression of TNF-α (LPS-activated RAW264.7 cells) and MTT experiment on LPS-induced HUVECs proliferation effects. Good suppressive effects on the expression of TNF-α were shown by 4 and 5 with IC50 values of 19.35 and 22.10 µM, respectively, compared to positive control indomethacin (IC50 16.40 µM). In addition to this, some isolated compounds exhibited excellent antioxidant activities including compounds 16, 18, 29, 39, and 47 (IC50 µM: 82.59, 72.94, 33.65, 46.67, and 20.81, respectively) with almost the same or stronger potency with reference to vitamin C as positive control (IC50 81.83 µM).

Phytochemical and pharmacognostic studies of Buddleja asiatica leaves.

Buddleja asiatica commonly known as "Booi" is a large deciduous shrub belongs to family Scrophulariaceae, traditionally used as antipyretic, analgesic, hypotensive, antimicrobial, anti-inflammatory, and antifungal agent recorded from essential oil obtained from leaves. The literature revealed that the plant has been widely used for many other purposes. The said plant has been analyzed through pharmacognostic techniques such as morphological, microscopic, and physio-chemical evaluations to keep the originality of the plant and to avoid adulteration. Morphologically, the plant is evergreen shrub, while organoleptic studies showed that the leaf has glabrous upper surface and tomentose lower surface, with slightly bitter taste and aromatic odor. Anatomically, the leaf showed typical dicot histological differentiation with hypostomatic nature having highest frequency (90%) of actinocytic stomata. The average stomatal number and stomatal index were 336 ± 39.5 and 30.01 ± 2.34, respectively. The palisade cell ratio, vein termination, and vein islet number were 9.2 ± 0.72, 10.2 ± 3.1, and 10.3 ± 3.3, respectively. Various tissue fragments have been observed during powdered drug analysis of the leaf. Preliminary phytochemical screening confirmed the presence of proteins, phenols, alkaloids, saponins, flavonoids, tannins, and glycosides. Fluorescence analysis in ordinary day light and under UV light along with extractive values was also analyzed. The above-mentioned studies that have been reported, for the first time, for the said plant may be significant to establish the pharmacognostic and phytochemical standards of the said species.

[A new hexenol glycoside from Buddleja officinalis].

The chemical constituents of the flower buds of Buddleja officinalis were investigated in this study. Eight compounds were isolated from the water extract of B. officinalis by column chromatography, and their structures were elucidated on the basis of physicochemical properties and spectral data. These compounds were identified as(Z)-hex-3-en-1-ol-1-O-ß-D-glucopyranosyl-(1→2)-[ß-D-xylcopyranosyl-(1→6)]-ß-D-glucopyranoside(1), ebracteatoside B(2), jasmonic acid-11-O-ß-D-glucopyranoside(3), 6-hydroxyluteolin-7-O-ß-D-glucopyranoside(4), luteolin-7-O-galacturonide(5), vicenin-2(6), decaffeoylverbascoside(7), and 6-O-(E)-feruloyl-D-glucopyranoside(8). Compound 1 is a new 3-hexenol glycoside. Compounds 2, 3, and 6 were isolated from Buddleja genus for the first time, and compounds 4 and 5 were isolated from this plant for the first time.

Photochemical reaction to increase melanogenesis using Buddleja officinalis and blue light-emitting diode irradiation in B16F10.

Recently, the incidence of vitiligo has increased because of stresses induced by external environment. Ultraviolet (UV) light therapy is the most commonly used method of treating the disease; however, UV light therapy requires a long treatment period, and prolonged exposure to UV radiation has side effects. The purpose of the present study was to investigate the effects of natural products and LED irradiation (LED-IR) on the synthesis of melanin. It was not possible to effectively increase intracellular melanin production through individual applications of Buddleja officinalis (BO), which is a natural substance selected through screening, or blue light irradiation (Blue-IR). However, when used in combination, these two agents stimulated adenylyl cyclase (AC) and melanin production was induced in the stimulated cells via the CREB/MITF/TYR pathway. Furthermore, the combined treatment with BO and Blue-IR generated low levels of cellular reactive oxygen species (ROS) and induced p38 phosphorylation, which in turn activated MITF in ROS-stimulated synthetic melanocytes, resulting in the promotion of melanogenic pathways other than the CREB/MITF/TYR pathway. In addition, this treatment combination effected melanin transport. These results suggested that the combined therapies can be used to treat melanin-deficiency skin diseases such as vitiligo.

Genome-wide analysis of butterfly bush (Buddleja alternifolia) in three uplands provides insights into biogeography, demography and speciation.

Understanding processes that generate and maintain large disjunctions within plant species can provide valuable insights into plant diversity and speciation. The butterfly bush Buddleja alternifolia has an unusual disjunct distribution, occurring in the Himalaya, Hengduan Mountains (HDM) and the Loess Plateau (LP) in China. We generated a high-quality, chromosome-level genome assembly of B. alternifolia, the first within the family Scrophulariaceae. Whole-genome re-sequencing data from 48 populations plus morphological and petal colour reflectance data covering its full distribution range were collected. Three distinct genetic lineages of B. alternifolia were uncovered, corresponding to Himalayan, HDM and LP populations, with the last also differentiated morphologically and phenologically, indicating occurrence of allopatric speciation likely to be facilitated by geographic isolation and divergent adaptation to distinct ecological niches. Moreover, speciation with gene flow between populations from either side of a mountain barrier could be under way within LP. The current disjunctions within B. alternifolia might result from vicariance of a once widespread distribution, followed by several past contraction and expansion events, possibly linked to climate fluctuations promoted by the Kunlun-Yellow river tectonic movement. Several adaptive genes are likely to be either uniformly or diversely selected among regions, providing a footprint of local adaptations. These findings provide new insights into plant biogeography, adaptation and different processes of allopatric speciation.

Polyphenolic Compounds Extracted and Purified from Buddleja Globosa Hope (Buddlejaceae) Leaves Using Natural Deep Eutectic Solvents and Centrifugal Partition Chromatography.

Chemical profiling of Buddleja globosa was performed by high-performance liquid chromatography coupled to electrospray ionization (HPLC-DAD-ESI-IT/MS) and quadrupole time-of-flight high-resolution mass spectrometry (HPLC-ESI-QTOF/MS). The identification of 17 main phenolic compounds in B. globosa leaf extracts was achieved. Along with caffeoyl glucoside isomers, caffeoylshikimic acid and several verbascoside derivatives (ß-hydroxyverbascoside and ß-hydroxyisoverbascoside) were identified. Among flavonoid compounds, the presence of 6-hydroxyluteolin-7-O-glucoside, quercetin-3-O-glucoside, luteolin 7-O-glucoside, apigenin 7-O-glucoside was confirmed. Campneoside I, forsythoside B, lipedoside A and forsythoside A were identified along with verbascoside, isoverbascoside, eukovoside and martynoside. The isolation of two bioactive phenolic compounds verbascoside and forsythoside B from Buddleja globosa (Buddlejaceae) was successfully achieved by centrifugal partition chromatography (CPC). Both compounds were obtained in one-step using optimized CPC methodology with the two-phase solvent system comprising ethyl acetate-n-butanol-ethanol-water (0.25:0.75:0.1:1, v/v). Additionally, eight Natural Deep Eutectic Solvents (NADESs) were tested for the extraction of polyphenols and compared with 80% methanol. The contents of verbascoside and luteolin 7-O-glucoside after extraction with 80% methanol were 26.165 and 3.206 mg/g, respectively. Among the NADESs tested in this study, proline- citric acid (1:1) and choline chloride-1, 2- propanediol (1:2) were the most promising solvents. With these NADES, extraction yields for verbascoside and luteolin 7-O-glucoside were 51.045 and 4.387 mg/g, respectively. Taken together, the results of this study confirm that CPC enabled the fast isolation of bioactive polyphenols from B. globosa. NADESs displayed higher extraction efficiency of phenolic and therefore could be used as an ecofriendly alternative to classic organic solvents.

Verbascoside-enriched fraction from Buddleja cordata Kunth ameliorates the effects of diabetic embryopathy in an animal model.

BACKGROUND: The deleterious effects of diabetes mellitus (DM) over development are apparently due to an increase in oxidative stress. Some antioxidants could prevent developmental alterations produced by diabetic state. Extracts of plants of the genus Buddleja are used traditionally for Mexican indigens to ameliorate some diseases. The purpose of this work was to evaluate the effect of the extract of Buddleja cordata over diabetic embryopathy. METHODS: Two experimental approaches were used: an in vivo study and an in vitro model. In the first, rats were treated with streptozotocin, streptozotocin plus methanolic extract of B. cordata, or none. Females were sacrificed at gestational day (GD) 19, and biochemical clinical parameters were measured; also, the fetuses were obtained and morphologically analyzed. In the in vitro model, a verbascoside-enriched fraction (VEF) of the extract was used in whole embryo culture in order to search for the mechanisms for embryoprotection effect over hyperglycemia-induced malformations. RESULTS: In the in vivo experiments, B. cordata extract reduces the frequency and severity of fetal malformations produced by chemically induced diabetes, and additionally partially ameliorates the diabetic condition; in the in vitro model, both severity and frequency of embryo dysmorphogenesis were reduced by the VEF; also, this fraction reduces lipoperoxidation without affecting the activity of the antioxidant enzymes. CONCLUSION: The results suggest that verbascoside of methanolic extract and enriched fraction can directly affect the redox state, and thus, prevents the embryotoxicity mediated by oxidative stress, in embryos of diabetic pregnancy.

Natural hybridization between two butterfly bushes in Tibet: dominance of F1 hybrids promotes strong reproductive isolation.

BACKGROUND: It has been recognized that a certain amount of habitat disturbance is a facilitating factor for the occurrence of natural hybridization, yet to date we are unaware of any studies exploring hybridization and reproductive barriers in those plants preferentially occupying disturbed habitats. Buddleja plants (also called butterfly bush) generally do grow in disturbed habitats, and several species with hybrid origin have been proposed, based solely on morphological evidence. RESULTS: In the present study, we test the hypothesis that B. × wardii is of natural hybridization origin in two sympatric populations of three taxa including B. × wardii and its parents (B. alternifolia and B. crispa) plus 4 referenced parental populations, using four nuclear genes and three chloroplast intergenic spacers, as well as with 10 morphological characters. Our results suggest that at both sites B. × wardii is likely to be a hybrid between B. alternifolia and B. crispa, and moreover, we confirm that most of the hybrids examined are F1s. That these plants are F1s is further supported by morphology, as no transgressive characters were detected. B. crispa was found to be the maternal parent in the Bahe (BH) population, from cpDNA evidence. However, in the Taji (TJ) population, the direction of hybridization was difficult to establish due to the shared cpDNA haplotypes between B. alternifolia and B. crispa, however we still predicted a similar unidirectional hybridization pattern due to results from cross-specific pollination treatments which supported the "SI × SC rule". CONCLUSIONS: The presence of mainly F1 hybrids can successfully impede gene flow and thus maintain species boundaries in parental species in a typical distribution of Buddleja, i.e. in disturbed habitats.