Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Penstemon”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed1998

Diploid hybrid speciation in Penstemon (Scrophulariaceae).

Hybrid speciation has played a significant role in the evolution of angiosperms at the polyploid level. However, relatively little is known about the importance of hybrid speciation at the diploid level. Two species of Penstemon have been proposed as diploid hybrid derivatives based on morphological data, artificial crossing studies, and pollinator behavior observations: Penstemon spectabilis (derived from hybridization between Penstemon centranthifolius and Penstemon grinnellii) and Penstemon clevelandii (derived from hybridization between P. centranthifolius and P. spectabilis). Previous studies were inconclusive regarding the purported hybrid nature of these species because of a lack of molecular markers sufficient to differentiate the parental taxa in the hybrid complex. We developed hypervariable nuclear markers using inter-simple sequence repeat banding patterns to test these classic hypotheses of diploid hybrid speciation in Penstemon. Each species in the hybrid complex was genetically distinct, separated by 10-42 species-specific inter-simple sequence repeat markers. Our data do not support the hybrid origin of P. spectabilis but clearly support the diploid hybrid origin of P. clevelandii. Our results further suggest that the primary reason diploid hybrid speciation is so difficult to detect is the lack of molecular markers able to differentiate parental taxa from one another, particularly with recently diverged species.

Biological Evolution↗
PubMed2001

Vestigial organs as opportunities for functional innovation: the example of the Penstemon staminode.

Vestigial organs arise commonly during morphological evolution, but they need not be destined for elimination. Instead, vestigial organs may facilitate functional innovation because their freedom from functional constraints allows them to assume novel roles that their functional progenitor could not perform. We illustrate this vestigial transition between functions with an experimental study of the staminode of Penstemon flowers. Previous phylogenetic and developmental studies indicate that this staminode represents a stamen that was lost phenotypically, but not genetically, and then reappeared in the tribe Cheloneae, to which Penstemon belongs. To assess whether the Penstemon staminode has adopted a novel function(s), we compared pollination of flowers with and without staminodes for two bee-pollinated species, P. ellipticus and P. palmeri, and two hummingbird-pollinated species, P. centranthifolius and P. rostriflorus. The staminode acts differently in the two bee-pollinated species. For P. ellipticus, which represents the basal Penstemon lineage, the staminode hinders pollinator access to nectar, which increases visit duration and pollinator contact with sexual organs, thereby increasing pollen receipt by stigmas and controlling pollen removal from anthers. In contrast, in P. palmeri, the staminode acts as a lever that enhances stigma contact with the pollinator, so that staminode removal reduced pollen receipt, but did not affect pollinator attraction, visit duration, or pollen removal. Unlike in bee-pollinated species. staminode removal from hummingbird-pollinated species did not affect any measured aspect of pollination, indicating that the staminode serves no function in this derived pollination system. These results illustrate several features of vestigial organs: loss of function can be temporary; loss of function facilitates the evolution of novel roles; and functional reinvention will often involve only a single role, thus increasing the chance of both secondary loss of function (bird-pollinated penstemons) and functional switches (P. palmeri).

Animals↗
PubMed2000

Hummingbird-Syndrome Traits, Breeding System, and Pollinator Effectiveness in Two Syntopic Penstemon Species.

Red-flowered, tubular Penstemon barbatus and Penstemon pinifolius, which have probably adapted independently to hummingbird pollinators, coflower on recently burned high-elevation slopes in the Chiricahua Mountains in Arizona. Hummingbirds visit both species but visit P. barbatus at a higher rate. We compared several traits and asked whether the species differed in specialization for hummingbird pollination. The corollas of P. pinifolius were 30% narrower than those of P. barbatus, but they were similar in tube length. Although a narrower corolla appeared to decrease access by large insects, small halictid bees were the only common insect visitors, and they gathered nectar from both species. Species differences in nectar production rate and concentration were minor, being smaller than within-species differences between dry and rainy periods. Taller inflorescences and a wider corolla tube may contribute to greater hummingbird use of P. barbatus. Penstemon pinifolius was fully self-compatible and weakly autogamous, whereas P. barbatus was strongly self-incompatible and had a longer flower life. Exclusion of hummingbirds reduced seed set fourfold in both species, supporting the inference from morphology and rewards that hummingbirds are the primary pollinators. In the absence of hummingbirds, halictids increased the seed set of P. barbatus relative to exclusion of all visitors, but they did not increase the seed set of P. pinifolius. Despite sharing the basic set of hummingbird-syndrome traits, the two species differed in degree of investment in individual flowers and in adaptations for outcrossing.

Journal Article↗
PubMed2003

Pollen transfer by hummingbirds and bumblebees, and the divergence of pollination modes in Penstemon.

We compared pollen removal and deposition by hummingbirds and bumblebees visiting bird-syndrome Penstemon barbatus and bee-syndrome P. strictus flowers. One model for evolutionary shifts from bee pollination to bird pollination has assumed that, mostly due to grooming, pollen on bee bodies quickly becomes unavailable for transfer to stigmas, whereas pollen on hummingbirds has greater carryover. Comparing bumblebees and hummingbirds seeking nectar in P. strictus, we confirmed that bees had a steeper pollen carryover curve than birds but, surprisingly, bees and birds removed similar amounts of pollen and had similar per-visit pollen transfer efficiencies. Comparing P. barbatus and P. strictus visited by hummingbirds, the bird-syndrome flowers had more pollen removed, more pollen deposited, and a higher transfer efficiency than the bee-syndrome flowers. In addition, P. barbatus flowers have evolved such that their anthers and stigmas would not easily come into contact with bumblebees if they were to forage on them. We discuss the role that differences in pollination efficiency between bees and hummingbirds may have played in the repeated evolution of hummingbird pollination in Penstemon.

Adaptation, Biological↗
PubMed1995

Verbascoside derivatives and iridoid glycosides from Penstemon crandallii.

The new phenylethanoid glycosides 2-O-acetyl-3'''-O-methylverbascoside and 2,4"-di-O-acetyl-3'''-O-methylverbascoside were isolated and identified from Penstemon crandallii. The major iridoid glycoside was plantarenaloside and no aucubin type iridoids were found. This contrasted with a previous analysis of P. teucrioides, from the same Penstemon subsection, which was dominated by aucubin derivatives.

Carbohydrate Conformation↗
PubMed2004

'Anti-bee' and 'pro-bird' changes during the evolution of hummingbird pollination in Penstemon flowers.

Floral phenotypes may be as much the result of selection for avoidance of some animal visitors as selection for improving the interaction with better pollinators. When specializing on hummingbird-pollination, Penstemon flowers may have evolved to improve the morphological fit between bird and flower, or to exclude less-efficient bees, or both. We hypothesized how such selection might work on four floral characters that affect the mechanics of pollen transfer: anther/stigma exsertion, presence of a lower corolla lip, width of the corolla tube, and angle of flower inclination. We surgically modified bee-pollinated P. strictus flowers changing one trait at a time to make them resemble hummingbird-pollinated P. barbatus flowers, and measured pollen transfer by bumblebees and hummingbirds. Results suggest that, apart from 'pro-bird' adaptations, specific 'anti-bee' adaptations have been important in shaping hummingbird-flowers. Moreover, some trait changes may have been selected for only if changing in concert with other traits.

Adaptation, Biological↗
PubMed1992

[Analysis of phenolic acids in cultured cells and in Penstemon Serrulatus Menz].

Qualitative and quantitative content of aromatic acids in callus tissues, cells in suspension cultures and intact plants of Penstemon serrulatus was determined by paper and gas chromatography. It has been observed that these acids occur in the investigated material mainly in bounded form. The largest quantities of phenolic acids were produced by callus tissues grown on Schenk and Hildebrandt's medium. The total content of aromatic acids found in the cells from suspension cultures was similar to the content of these compounds in intact plants, but twice lower than in callus tissue grown on the same medium.

Cells, Cultured↗
PubMed1998

Iridoid glycoside biosynthesis in Penstemon secundiflorus. Another H-5, H-9 trans-iridoid glycoside.

Isolation and characterization of the new iridoid 10-hydroxy-(5 alpha H)-6-epidihydrocornin from Penstemon secundiflorus (Scrophulariaceae) is described. In biosynthetic experiments, deoxyloganic acid was incorporated into the trans-fused iridoid glycosides (5 alpha H)-6-epidihydrocornin and 10-hydroxy-(5 alpha H)-6-epidihydrocornin in P. secundiflorus. Formation of the trans-fused compounds is therefore a late event in the biosynthesis and does not occur during iridoid formation by cyclization of the open chain monoterpene precursor. In the same plant, 8-epideoxyloganic acid was not incorporated into the trans-iridoids. Deoxyloganic acid was also incorporated into 10-hydroxyhastatoside (which bears an 8 beta-methyl group), while 8-epideoxyloganic acid was incorporated into penstemoside (with an 8 alpha-methyl group). Thus, iridoid biosynthetic pathways leading from both deoxyloganic acid and 8-epideoxyloganic acid were found in the same plant.

Glucosides↗
PubMed1998

Trans-fused iridoid glycosides from Penstemon mucronatus.

Two new trans-fused iridoid glycosides (5 alpha H)-6 alpha-8-epidihydrocornin and (5 alpha H)-6 alpha-8-hydroxy-8-epiloganin, were isolated from Penstemon mucronatus, along with cornin, penstemoside and three hastatosides. The trans-fused iridoids are only the second and third known among over 900 described cis-fused iridoid glycosides. Two pairs of iridoids, identical except for the stereochemistry at C-8, were found. Structures were determined by spectroscopic methods.

Carbohydrate Conformation↗
PubMed2005

Antioxidant activities of extracts from Barkleyanthus salicifolius (Asteraceae) and Penstemon gentianoides (Scrophulariaceae).

Various extracts of the aerial parts of Barkleyanthus salicifolius (Asteraceae) and Penstemon gentianoides (Scrophulariaceae) have been used in folk medicine to treat many ailments, particularly inflammation and migraine. Neither the bioactive components responsible nor the mechanisms involved have been evaluated. Here are reported antioxidant activities of their methanol, dichloromethane, and ethyl acetate extracts. Samples were evaluated for oxygen radical absorption capacity (ORAC), ferric reducing antioxidant power (FRAP), 2,2-diphenyl-1-picryl-hydrazyl (DPPH) radical scavenging, and inhibition of the formation of thiobarbituric acid reactive species (TBARS), a measure of lipid peroxidation. Antioxidant activities were strongly correlated with total polyphenol content. The most active extracts from P. gentianoides in scavenging DPPH radicals and inhibiting TBARS formation were the methanol extract (A) and a further ethyl acetate extract of this (E). Partition E was further divided into eight fractions, and both E and the fractions were compared for activity against butylated hydroxytoluene, quercetin, and tocopherol. Partition E and the most active fractions, 5 and 6, were found to have I(50) values of 14.1, 38.6, and 41.8 ppm, respectively, against DPPH and 18.5, 26.0, and 12.7 ppm, respectively, against TBARS formation. Consistent with this finding, partition E and fractions 4-6 had the greatest ORAC and FRAP values. These results show that these plants could be useful antioxidant sources.

Antioxidants↗
PubMed1992

Studies on iridoids of tissue cultures of Penstemon serrulatus: isolation and their antiproliferative properties.

Penstemide and serrulatoloside as well as penstemide aglycone and serrulatoloside aglycone were isolated and identified in the calli and suspension cultures of Penstemon serrulatus. The influence of serrulatoloside, penstemide, and its aglycone on the spontaneous proliferation of mouse spleen lymphocytes or hepatoma cells in the Syrian hamster has been estimated in vitro. It has been found that these compounds produce a dose-dependent inhibition of [3H]-thymidine incorporation into the DNA of the examined cells.

Animals↗
PubMed1999

Phenylpropanoid glycosides from Penstemon serrulatus.

Two new phenylpropanoid glycosides named cis-martynoside (1) and cis-leucosceptoside A (3) were recognized in cell suspension cultures of Penstemon serrulatus Menz. The structures of these compounds were determined on the basis of 1H NMR spectral data.

Carbohydrate Conformation↗
PubMed1998

Phenylethanoid glycosides from Digitalis purpurea and Penstemon linarioides with PKCalpha-inhibitory activity.

In a continuation of our search for potential tumor inhibitors from plants, it was found that the CH2Cl2-MeOH (1:1) extracts from Digitalis purpurea and Penstemon linarioides both showed PKCalpha-inhibitory bioactivity. Bioassay-directed fractionation of the extract from D. purpurea yielded the new, weakly active phenylethanoid glycoside 2-(3-hydroxy-4-methoxy-phenyl)-ethyl-O-(alpha-L-rhamnosyl)-(1-->3) -O- (alpha-L-rhamnosyl)-(1-->6)-4-O-E-feruloyl-beta-D-glucopy ran oside (1) together with the four known compounds calceolarioside A (2), calceolarioside B (3), forsythiaside (4), and plantainoside D (5). The extract from P. linarioides yielded the three known glycosides leucosceptoside A (6), acteoside (7), and poliumoside (8), together with the iridoid plantarenaloside (9). All of the isolated compounds, except compound 9, showed inhibitory activity against PKCalpha with IC50 values (in microM) of 125 (1), 0.6 (2), 4.6 (3), 1.9 (4), 14.8 (5), 19.0 (6), 9.3 (7), and 24.4 (8).

Caffeic Acids↗
PubMed1998

Assessing hybridization in natural populations of Penstemon (Scrophulariaceae) using hypervariable intersimple sequence repeat (ISSR) bands.

Inferences regarding hybridization rely on genetic markers to differentiate parental taxa from one another. Intersimple sequence repeat (ISSR) markers are based on single-primer PCR reactions where the primer sequence is derived from di- and trinucleotide repeats. These markers have successfully been used to assay genetic variability among cultivated plants, but have not yet been tested in natural populations. We used genetic markers generated from eight ISSR primers to examine patterns of hybridization and purported examples of hybrid speciation in Penstemon (Scrophulariaceae) in a hybrid complex involving P. centranthifolius, P. grinnellii, P. spectabilis and P. clevelandii. This hybrid complex has previously been studied using three molecular data sets (allozymes, and restriction-site variation of nuclear rDNA and chloroplast DNA). These studies revealed patterns of introgression involving P. centranthifolius, but were unsuccessful in determining whether gene flow occurs among the other species, and support for hypotheses of diploid hybrid speciation was also lacking. In this study, we were able to fingerprint each DNA accession sampled with one to three ISSR primers and most accessions could be identified with a single primer. We found population- and species-specific markers for each taxon surveyed. Our results: (i) do not support the hybrid origin of P. spectabilis; (ii) do support the hypothesis that P. clevelandii is a diploid hybrid species derived from P. centranthifolius and P. spectabilis; and (iii) demonstrate that pollen-mediated gene flow via hummingbird vectors is prevalent in the hybrid complex.

California↗
PubMed1991

Iridoid Glucosides from Penstemon nitidus.

From the leaves of PENSTEMON NITIDUS Dougl. (smooth blue beardtongue) besides the known iridoid glucosides cornin (syn. verbenalin), hastatoside and beta-dihydrohastatoside the new compound 10-hydroxycornin has been isolated. The structures of all compounds were established by spectroscopic means (FD-MS, (1)H-, (13)C-, 2D-NMR, and NOE). This is the first report of cornin and analogous 6-keto iridoids in scrophulariaceous plants. Up to now iridoid glucosides like these have only been found in plants belonging to the Cornaceae and its allies and to the Lamiaceae-Verbenaceae complex.

Journal Article↗
PubMed1991

5''-Hydroxydigipenstroside and Penstriatoside: Novel Dimeric and Trimeric Open-Chain Monoterpene Glucosides from Penstemon digitalis*.

A new dimeric open-chain monoterpene glucoside, 5''-hydroxydigipenstroside {1-beta- D-glucopyranosyl)-8-[5'',8''-dihydroxy-2'',6''-dimethyl-2''( E),6''( E)-octadienoyl]-5,8-dihydroxy-2,6-dimethyl-2( E),6( E)-octadienoate} has been isolated from leaves of PENSTEMON DIGITALIS Nutt. In addition, the novel trimeric open-chain monoterpene glucoside penstriatoside {1-(beta- D-glucopyranosyl)-8-[5'',8''-dihydroxy-2'',6''-dimethyl-2''( E),6''( E)-octadienoyl-8''-(5''',8'''-dihydroxy-2''',6'''-dimethyl-2''' ( E)6'''( E)-octadienoyl)]-5,8-dihydroxy-2,6-dimethyl-2 ( E),6( E)-octadienoate} has been encountered. The structures of both compounds have been elucidated by spectroscopic means (FD-, FAB-mass, (1)H-, (13)C-NMR, COSY, DEPT).

Journal Article↗