Abstracts Dealing with Parasitic Angiosperms
Botany 2008
University of British Columbia, Vancouver BC, July 26-30, 2008

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Orobanchaceae

Yatskievych, George [1], Contreras Jiménez, José Luis [2].
A New Genus of Holoparasitic Orobanchaceae Endemic to Guerrero, Mexico.
Recent field and herbarium studies have resulted in the discovery of a new, achlorophyllous, root-parasitic angiosperm. This perennial taxon apparently is endemic to a small area on the inland side of the Sierra Madre del Sur in Guerrero, Mexico. It parasitizes large lateral roots of mature trees of Hedyosmum mexicanum (Chloranthaceae) in steep-walled, headwater ravines dominated by montane evergreen tropical hardwoods. These drainages are isolated in a matrix of otherwise mainly pine-oak forest on adjacent slopes. Morphological features that ally the new taxon with the Orobanchaceae include: 1) the parasitic habit; 2) details of corolla shape and aestivation; 3) production of 4 stamens with loosely connivent anthers; 4) parietal placentation; 5) a hollow style terminating in a discoid-crateriform stigma with a central pore; 6) seeds with a prominent, loose, reticulate outer testa in which the enlarged cells rupture into concave, polygonal facets. However, the new taxon is amply distinct within the family and is discussed as a new genus and species. Autapomorphies that result in an expansion of the morphological circumscription of Orobanchaceae include: 1) the strongly 5-ribbed ovary and fruit; 2) production of 5 (vs. 2 or 4) parietal placentae; 3) unusual anthers in which the pollen sacs are more or less embedded in the expanded filament apex; 4) regularly pantohexaporate pollen grains.
1 - Missouri Botanical Garden, P.O. Box 299, St. Louis, Missouri, 63166, USA
2 - Universidad Autónoma de Puebla, Herbario y Jardín Botánico de la Benemérita, Edif. 76 Unidad de Ciencias C.U., Av. San Claudio s/n, Col. San Manuel, Puebla, Puebla, CP 72580, México
Session: 55
Location: 177/Law
Date: Wednesday, July 30th, 2008
Time: 9:00 AM
Number: 55005
Abstract ID:594

Mathews, Sarah [1], Schneeweiss, Gerald M. [2], Yatskievych, George [3].
Phylogenetic affinities of a new holoparasitic genus of Orobanchaceae endemic to Guerrero, Mexico, inferred from molecular data.
We have tested the familial placement of a new genus being described from the Sierra Madre del Sur in Guerrero, Mexico, which parasitizes large lateral roots of mature trees of Hedyosmum mexicanum (Chloranthaceae). A number of morphological features suggest affinity with the Orobanchaceae, including: 1) the parasitic habit; 2) production of 4 stamens with loosely connivent anthers; 3) parietal placentation; 4) a hollow style terminating in a discoid-crateriform stigma with a central pore; 5) seeds with a prominent, loose, reticulate outer testa in which the enlarged cells rupture into concave, polygonal facets. However, several autapomorphies would require expansion of the morphological circumscription of the family. Our molecular studies confirm that the new taxon is a previously undescribed, holoparasitic member of the Orobanchaceae. Data from ITS and rps2 suggest that it belongs to a clade including Boschniakia, Conopholis, and Epifagus, but currently are not definitive regarding its placement among these genera. Data from phytochromes A and B provide strong evidence of a clade of holoparasitic genera that includes Boschniakia/Kopsiopsis, Conopholis, and Epifagus, as well as Orobanche sensu lato, Cistanche, and Mannagettaea. Within the holoparasitic clade, the phytochrome data strongly support the clade of Boschniakia/Kopsiopsis, Conopholis, and Epifagus. Thus, we are further testing the placement of the new genus with additional data from phytochromes. However, the ITS and rps2 data suggest that, as with morphology, the genus is characterized by a large number of molecular autapomorphies.
1 - Harvard University, Arnold Arboretum, Harvard University Herbaria, 22 Divinity Avenue, Cambridge, Massachusetts, 02138, USA
2 - University of Vienna, Department of Biogeography, Rennweg 14, Vienna, Vienna, A-1030, Austria
3 - Missouri Botanical Garden, Po Box 299, St Louis, Missouri, 63166-0299, USA
Session: 55
Location: 177/Law
Date: Wednesday, July 30th, 2008
Time: 9:15 AM
Number: 55006
Abstract ID:858

Morawetz, Jeffery J. [1], Randle, Christopher P. [2], Wolfe, Andrea D. [3].
Detangling Melasma (Orobanchaceae): One genus or two?
The hemiparasitic genera Alectra and Melasma have always been considered closely related. Their distribution is primarily African with 2 species each in tropical America. They share a campanulate calyx and corolla, but differ in that Alectra has sessile flowers and a marcescent corolla, while Melasma has pedicellate flowers and an accrescent calyx. Recent molecular data suggests the hemiparasitic American genus Escobedia could be sister to Alectra + Melasma, despite obvious differences in floral morphology, but each genus was only represented by a single species, and the American species of Alectra and Melasma were not included. The relationships among these genera were examined with an expanded 3-gene dataset including both American species of Alectra and Melasma, and 5 species of Escobedia. The American species of Alectra are shown to be embedded within the genus, supporting previous work. Melasma, however, is shown to comprise two distinct lineages, one African and one American, and the American lineage is supported as sister to Escobedia. The African lineage of Melasma is sister to the American lineage + Escobedia, and Alectra is then sister to these taxa. Further morphological examination of the American Melasma species is necessary to determine whether they should be transferred to Escobedia, or be accommodated within a newly described genus.
1 - University of Michigan, Ecology and Evolutionary Biology, 2035 Kraus Natural Science Bldg., 830 N. University Ave., Ann Arbor, MI, 48109, USA
2 - Sam Houston State University, Department of Biological Sciences, 1900 Avenue I., Huntsville, TX, 77340
3 - Ohio State University, Department of Evolution, Ecology and Organismal Biology, 300 Aronoff Laboratory, 318 W. 12th Ave., Columbus, Ohio, 43210-1293, USA
Session: 55
Location: 177/Law
Date: Wednesday, July 30th, 2008
Time: 9:30 AM
Number: 55007
Abstract ID:70

Tsai, Yi-Hsin Erica [1], Manos, Paul S. [2].
Beechdrops on the move: A parasitic plant's tale of host influences on post-glacial recolonization.
While phylogeographies of tree species reconstruct the range expansions of those species, as individual data points they are insufficient to recount the distributional history of the forest community. Species respond individually to climate change, so how communities assemble can only be understood through examination of multiple species histories from a diversity of forest niches. We present work on an understory, parasitic herb (Epifagus virginiana, beechdrop, Orobanchaceae) that has an obligate and host specific relationship with a common eastern North American forest tree (Fagus grandifolia, American beech, Fagaceae). Two chloroplast DNA regions were sequenced and used to reconstruct the post-glacial migration history of E. virginiana. Through use of landscape genetic techniques, coalescent methods, and assignment tests, we elucidate the migration routes of this parasitic plant.  E. virginiana is shown to have migrated from the southern Appalachians into the Northeast and then westward into the Midwest. These data are then used to distinguish between hypotheses of recolonization routes based on host data. The parasite's pattern of expansion parallels the development of beech forests as recorded in the pollen record and differs from reports of the initial range expansion of beech as seen in a molecular phylogeography. Comparisons of the parasite and host's histories show that the herb lagged behind the initial expansion of the tree's range and instead modified its distribution based on changes in host density. The composite migration history of this parasite and its host shows how two diverse components of a forest community colonized the landscape separately -- even as aspects of the host's distribution greatly influenced the path of the parasite -- before reassembling into their present day co-distributed range.
1 - Duke University, Department of Biology, Box 90338, 137 Biological Sciences Building, Durham, NC, 27708, USA
2 - Duke University, Department of Biology, 137 Biological Sciences, Durham, NC, 27708, USA
Session: 15
Location: 177/Law
Date: Monday, July 28th, 2008
Time: 1:30 PM
Number: 15003
Abstract ID:477

Cuscuta (Convolvulaceae)

Wright, Michael [1], Stefanovic, Sasa [2], Costea, Mihai [3].
Cuscuta salina (Salt marsh dodder; Convolvulaceae): one species or two?
Cuscuta salina refers to an assemblage of inbreeding forms that parasitize hosts growing in alkaline/saline habitats from western North America. Three varieties have been historically described to encompass the morphologic variation displayed by these parasitic plants: var. salina, var. major, and var. papillata. A morphometric study of flower characters, SEM, and DNA sequence data from plastid and nuclear regions were used to analyze the patterns of variation, define lineages/taxa and investigate their phylogenetic relationships. Principal components, canonical, and clustering analyses, as well as the molecular results indicate that only two lineages/taxa can be distinguished. These lineages are sister taxa and correspond largely to var. salina and var. major. Cuscuta salina var. papillata, in the strict sense defined by Yuncker, clusters with var. major, from which it differs through the presence of papillae on the calyx. The two main lineages, 'salina' and 'major', share a small area of sympatry in southern and Lower California, but otherwise have a distinct biogeography and host specificity. ‘Salina’ occurs mostly in inland vernal pools and salt flats from California, Nevada, Arizona and Mexico and grows primarily on Frankenia and Suaeda. ‘Major’ can be found in coastal salt marshes from British Columbia to Baja California, on Salicornia and Jaumea carnosa. Morphologically ‘salina’ has smaller flowers, 2.5–4 (4.5) mm long and cylindric to narrow campanulate corollas with ovate-lanceolate lobes, while in ‘major’ flowers are 3.75–5(5.5) mm long and corollas campanulate with broadly ovate lobes. Infrastaminal scales are shorter and with less fimbria in ‘major’, compared to ‘salina’. Taking into account their reproductive isolation, morphological, biogeographic and host distinctiveness, the two lineages can alternatively be treated at specific rank, in which case the description of a new species for the latter is required.
1 - Wilfrid Laurier University, Biology, 75 University Avenue W, Waterloo, Ontario, N2L 3C5, Canada
2 - University of Toronto at Mississauga, Biology, 3359 Mississauga Rd N, Mississauga, Ontario, L5L1C6, Canada
3 - Wilfrid Laurier University, Biology, 75 University Ave N, Waterloo, Ontario, N2L3C5, Canada
Session: P
Location: Ball Room & Party Room/SUB
Date: Monday, July 28th, 2008
Time: 12:30 PM
Number: PSP040
Abstract ID:515

Costea, Mihai [1], Stefanovic, Sasa [2].
Demanding equal rights for parasitic plants: systematics and conservation of Cuscuta jepsonii (Convolvulaceae), a Californian species presumed to be extinct.
Although numerous studies on the ecology of different parasitic plants have clearly shown that they act as keystone species and ecosystem engineers, their conservation is fraught with more challenges than autotrophic plants. These challenges stem from the overall negative image parasitic plants have received, especially in the groups that include some invasive or weedy species. The most successful parasitic plants are “the generalists”, capable of parasitizing a wide variety of hosts from different families. In contrast, “the specialists” are restricted to one or few host genera/species. Our observations on Cuscuta (dodders, Convolvulaceae) suggest not only that species from this latter category are extremely vulnerable and that the narrow host specialization is a good predictor of conservation problems, but also that “specialist” dodders are likely to develop conservation issues or even to become extinct before their hosts. Cuscuta jepsonii (Jepson’s dodder) represents such an example. This species is endemic to California and it is currently presumed extinct. Because it has been known only from the holotype, its phylogenetic affinities, morphologic variation, and ecology have remained unknown or at the stage of supposition. While examining Californian herbarium material for the treatment of Cuscuta in the Jepson Manual we have recently found additional specimens that allowed us to confidently place it in the Cuscuta californica clade, and not in the lineage of Cuscuta indecora as was recently proposed. Taking into account the phylogeny and the ecology of the only two known host species, Ceanothus prostratus and C. diversifolius (California lilacs, Rhamnaceae), we hypothesize that Cuscuta jepsonii may also parasitize other more or less prostrate species of Ceanothus with a similar ecology (e.g. Ceanothus pumilus, C. arcuatus, C. fresnensis), and we suggest that there are some chances Jepson’s dodder may be rediscovered in the future.
1 - Wilfrid Laurier University, Biology, 75 University Ave N, Waterloo, Ontario, N2L3C5, Canada
2 - University of Toronto at Mississauga, Biology, 3359 Mississauga Rd N, Mississauga, Ontario, L5L1C6, Canada
Session: 62
Location: 201/Law
Date: Wednesday, July 30th, 2008
Time: 1:00 PM
Number: 62001
Abstract ID:67

Stefanovic, Sasa [1], Costea, Mihai [2].
Multiple instances of reticulate evolution in the parasitic genus Cuscuta (dodders; Convolvulaceae).
The frequency and relative importance of hybridization in plants has been an area of intense debate. Although this evolutionary mechanism has received considerable attention from plant biologist, there are no well-supported cases of reticulate evolution involving holoparasitic plants to date. Recent molecular phylogenetic analyses revealed that the subgenus Grammica, the largest and most diverse group of the stem parasitic genus Cuscuta, consists of 15 major clades. We describe here five cases of strongly supported discordance between phylogenies derived from plastid and nuclear data and interpret them as results of five independent hybridization events. Three of these cases could represent relatively recent reticulations because each of them involves more closely related species, always confined within the same major clade as their putative parental species, and are currently sympatric or parapartric with them. The two remaining cases involve species whose potential progenitors are derived from different major groups of subgenus Grammica, and which are allopatric in their present distribution. This is consistent with more ancient hybridization events. Exemplary taxa illustrating these two cases (i.e., Cuscuta subsection Denticulatae and Cuscuta sandwichiana, respectively) are discussed in more detail.
1 - University of Toronto at Mississauga, Biology, 3359 Mississauga Rd N, Mississauga, Ontario, L5L1C6, Canada
2 - Wilfrid Laurier University, Biology, 75 University Ave N, Waterloo, Ontario, N2L3C5, Canada
Session: 62
Location: 201/Law
Date: Wednesday, July 30th, 2008
Time: 1:15 PM
Number: 62002
Abstract ID:350

Lewis, Kristin [1], Alers-García, Janice [1], Wright, Leslie [2].
Plant-derived polyphenolics inhibit parasitic plant germination and attachment.
We have previously shown that polyphenolics found in a common plant extract can be used to inhibit pectin methylesterase activity both in commercial extracts of the enzyme and in extracts of parasitic plants such as Cuscuta pentagona and Castilleja indivisa. Parasitic plants utilize cell wall degrading enzymes such as pectin methylesterase to invade host tissue and create functional attachments to the vasculature of their host; therefore, inhibiting these enzymes may confer resistance. We have utilized an exogenously applied solution of the aforementioned plant polyphenolics to inhibit germination and parasitism in the facultative hemiparasite Castilleja indivisa grown with Lupinus texensis, a naturally occuring host. We suggest that successful parasite inhibition through application of cell-wall-degrading-enzyme inhibitors as soil amendments may lead to novel forms of parasitic plant control.
1 - Harvard University, Rowland Institute at Harvard, 100 Edwin H. Land Blvd., Cambridge, MA, 02142, USA
2 - Harvard University, Rowland Institute at Harvard, 100 Edwin H. Land Blvd., Cambridge, MA, 02142, MA
Session: 59
Location: 157/Law
Date: Wednesday, July 30th, 2008
Time: 10:30 AM
Number: 59002
Abstract ID:156

Welsh, Mark [1], Stefanovic, Sasa [2], Costea, Mihai [3].
Pollen evolution and its systematic significance in Cuscuta (dodders, Convolvulaceae).
Pollen morphology of 150 species of Cuscuta was investigated in relation to a phylogeny obtained from a combined analysis of rbcL and 26S rDNA gene sequences. The size of the pollen grains, their shape, number of colpi, and exine characteristics were examined with the SEM. Considering that Cuscuta is one of the most diverse genera of parasitic plants, the pollen of dodders is surprisingly uniform. The largest infrageneric unit, Grammica, exhibits more variation than all the three other groups—Monogynella, Cuscuta, Pachystigma—combined. A reticulated pollen, defined by irregularly shaped lumina, 1500–3500 nm, is characteristic to Monogynella, and interestingly, several species of a South American clade of Grammica (Clade O). ‘Tectum imperforatum’ and ‘perforatum’ are largely shared by Cuscuta, Pachystigma and Grammica. In the former, tectum covers the small puncta (50–250 nm in diameter) and pollen grains appear smooth at magnifications lower than 4000x; in the latter puncta are visible (200–500 nm in diameter). Although the sister group of Cuscuta in Convolvulaceae is unknown, given the prevalence of tectate pollen in the genus and the family, and the fact that the reticulate condition is unknown in other genera, the latter is likely to be a synapomorphy. A similar pattern can be observed in the number of colpi, which is commonly three in most Cuscuta species and numerous Convolvulaceae, but 5 to 8 in some species of Monogynella and the clade O of Grammica. Additionally, in Grammica a ‘microreticulate’ pollen with more or less regular perforations, 500–1500 nm in diameter has evolved at least in five different clades. An intergradation between these morphological ‘types’ may occur in the subgenera Cuscuta, Pachystigma and Grammica indicating that although useful for taxonomic purpose, these tipologies represent merely ranges of variation within an evolutionary continuum.
1 - Wilfrid Laurier University, Botany, 75 University Avenue W, Waterloo, Ontario, N2L 3C5, Canada
2 - University of Toronto at Mississauga, Biology, 3359 Mississauga Rd N, Mississauga, Ontario, L5L1C6, Canada
3 - Wilfrid Laurier University, Biology, 75 University Ave N, Waterloo, Ontario, N2L3C5, Canada
Session: P
Location: Ball Room & Party Room/SUB
Date: Monday, July 28th, 2008
Time: 12:30 PM
Number: PSP026
Abstract ID:417

Santalales

Moore, Michael [1], Bell, Charles [2], Soltis, Pamela S. [3], Soltis, Douglas E. [4].
Analysis of an 83-gene, 86-taxon plastid genome data set resolves relationships among several recalcitrant deep-level eudicot lineages.
Over the past few years, the burgeoning field of plastid genomics has enabled systematists to use data sets of > 40,000 aligned bases to resolve several difficult deep-level nodes in the Angiosperm Tree of Life. For example, plastid genome-scale data sets have provided strong support for the successive sister relationships of Amborella, Nymphaeales, and Austrobaileyales to all other angiosperms, as well as for a clade of monocots + (Ceratophyllum + eudicots). Despite this progress, other deeper-level problem areas remain in angiosperm phylogeny, including the relationships among basal eudicot lineages, basal core eudicot lineages, and many basal lineages of rosids and asterids. As part of the Angiosperm Tree of Life project, we sequenced 27 eudicot plastid genomes, selected to cover all major basal eudicot and core eudicot lineages, in an effort to resolve recalcitrant nodes. By combining these new genomes with existing genomes, we created an 86-taxon, 66,741 bp alignment, including all 79 angiosperm plastid protein-coding genes and 4 rRNA genes. Maximum likelihood (ML)-based analyses of these data provided strong (> 90% ML bootstrap) or moderate (70-90% ML bootstrap) support for a resolution of several previously difficult-to-resolve eudicot nodes. Notable examples include (1) moderate support for a sister relationship between Sabiaceae and Proteales, (2) moderate support for a sister relationship of Dilleniaceae to a clade of Vitaceae, Saxifragales, and rosids, (3) moderate support for a sister relationship of Caryophyllales to asterids, and (4) strong support for the successive sister relationships of Santalales and Berberidopsidales to Caryophyllales + asterids. However, even with plastid genome-scale data, our analyses do not allow for confident topological resolution (ML bootstrap < 70%) among the following eudicot lineages: (1) Buxales, Trochodendrales, and core eudicots, (2) Vitaceae, Saxifragales, and rosids, and (3) the four lineages of basal lamiids included in our analyses (Boraginales, Lamiales, Solanales, and Gentianales).
1 - Oberlin College, Biology Department, 119 Woodland Street, Science Center K111, Oberlin, Ohio, 44074-1097, USA
2 - University of New Orleans, Department of Biological Sciences, New Orleans, LA, 70148, USA
3 - University of Florida, Florida Museum of Natural History, PO Box 117800, Gainesville, FL, 32611-7800, USA
4 - University of Florida, Department of Botany, 220 Bartram Hall, P.O. Box 118526, Gainesville, Florida, 32611-8526, USA
Session: 34
Location: Room 6/Woodward
Date: Tuesday, July 29th, 2008
Time: 10:30 AM
Number: 34010
Abstract ID:203

Su, Huei-Jiun [1], Hu, Jer-Ming [1].
Phylogenetic relationships of Balanophoraceae and Santalales based on floral B homeotic genes.
Balanophoraceae are obligate root parasites, which comprise 17 genera with 44 species in the tropics and subtropics. Plants of Balanophoraceae are composed of underground tuberous structures that attach to the host, and only emerge above ground during reproduction. Unlike typical flowers of the core eudicots that have differentiated sepals and petals, the flowers of Balanophoraceae are highly reduced and the remnant floral organs are sometimes difficult to interpret the ontological origins. Due to the extreme reduction of morphological features in Balanophoraceae, the phylogeny of Balanophoraceae has been controversial. Although recent molecular data shows Balanophoraceae might be close to Santalales, the exact position of Balanophoraceae remains in question. Previous studies also showed these parasitic plants have accelerated DNA substitution rates, which have caused problems in phylogenetic reconstruction. To clarify the affinities of Balanophoraceae and other Santalales members, we compared phylogenetic trees resulted from analyses of nuclear 18S rDNA and the floral B-class homeotic genes. A total of 23 B-class gene homologues were identified for Balanophoraceae and Santalales species. The results of various phylogenetic analyses confirm the basal position of Balanophoraceae in the Santalales. In addition, the substitution rates of B-class genes do not have drastic changes among Balanophoraceae, Santalales and other eudicots, compared with 18S rDNA. These results suggest that floral homeotic genes could be potential tools for reconstructing difficult phylogenies such as holoparasites.
1 - National Taiwan University, Institute of Ecology and Evolutionary Biology, Rm1227, Life Science Building, 1 Roosevelt Road, Sect.4, Taipei, 106, Taiwan
Presentation Type: Poster:Posters for Sections
Session: P
Location: Ball Room & Party Room/SUB
Date: Monday, July 28th, 2008
Time: 12:30 PM
Number: PSP082
Abstract ID:512

Nickrent, Daniel [1], García, Miguel [2], Mucina, Ladislav [3].
A phylogeny of Thesium (Santalaceae) using nuclear ribosomal ITS sequences.
With over 300 species, Thesium is the largest genus in Santalales. Worldwide in distribution, its highest diversity is in South Africa. Regional taxonomic works exist yet no modern comprehensive phylogenetic study is available. Thesium samples throughout its distribution were obtained and nuclear ribosomal ITS sequenced. Of the 294 sequences, 282 were from Thesium representing 165 names. Heuristic searches using MP did not finish, however, the strict consensus tree yielded a number of meaningful clades. With Buckleya as outgroup, Osyridocarpos and Thesium lineatum were sister to the remaining taxa, thus indicating that this Thesium should be recognized as a separate genus. These taxa formed two clades: A (Thesidium, Kunkeliella and Eurasian Thesium species) and B (mainly South and tropical Africa). Thesium mauritanicum  of North Africa was sister to all other clade A taxa, but within this clade little of the phylogenetic structure proposed by Hendrych was seen. Chrysothesium was not basalmost in Thesium nor monophyletic but related to Asian species in Section Macranthia.  Thesium spinosum  and T. spinulosum  were sister to the other clade B species. Plants with dichasial inflorescences occur in the next two clades (Section Imberbia Subsection Subglabra). The next clade is composed entirely of South African taxa, yet contains species assigned to both Sections Barbata and Annulata. The central portion of clade B contains mostly tropical African taxa, some of which form a clade approximately corresponding to Section Imberbia. Two of the three South American species (Section Psilothesium) are nested within the tropical African clade, thus their recognition as genus Austroamericium is not supported. Three Malagasy species also occur in this tropical African clade but are distantly related. The remainder of clade B is composed of ca. 30 taxa, all from Section Barbata. ITS sequences will continue to provide important data needed for a future revision of Thesium.
1 - Southern Illinois University, Department of Plant Biology, 1125 Lincoln Drive, Carbondale, Illinois, 62901-6509, USA
2 - Real Jardín Botánico, CSIC, Plaza de Murillo 2, 28014 Madrid, Spain
3 - University of Stellenbosch, Department of Botany & Zoology, Private Bag X1, 7602 Matieland, Stellenbosch, South Africa
Session: 34
Location: Room 6/Woodward
Date: Tuesday, July 29th, 2008
Time: 11:30 AM
Number: 34014
Abstract ID:239

Randle, Christopher P. [1], Williams, Justin [1], Lee, Stephen M. [1], Zychowski, Gregory V. [2], Reid, Ryan L. [1].
Host preference in leafy mistletoe, Phoradendron serotinum (Santalaceae).
Phoradendron serotinum is a hemiparasite that infects woody plants of Mexico and the United States. It has been the subject of taxonomic controversy, having been variously divided into additional species and subspecies. In the most recent and comprehensive treatment of the genus, variation in diagnostic characters among four subspecies is continuous, making host preference useful in distinguishing them. Seed germination appears to be mediated by the drying of the viscous layer that surrounds the seed and adheres it to the branch. Germination success appears to be independent of the physical structure of its substrate. On the other hand, haustorial disk formation, a preliminary sign of infective capability, is limited by the particular substrate provided by the host species. In previous studies of populations of P. serotinum subsp. tomentosum from central Texas, offspring of plants grown on one host species were poorly suited to infect a different host species. In east Texas, three of the subspecies overlap morphologically and geographically, making subspecific identification difficult. Although many other oak species and other deciduous dicotyledonous trees occur naturally in the area, infection on trees other than Quercus nigra is uncommon. In assessing host preference, it is important to document not only the local abundance of host species that are parasitized, but also the abundance of species that do not serve as hosts. In a pilot study conducted during the winter of 2007, all trees on the campus of Sam Houston State University were visited, identified, and surveyed for mistletoe infection, to test the following hypotheses: 1) Parasites exhibit preference for certain host species, 2) Parasites are unable to grow on some potential host species. Differences in host preference across the range of P. serotinum were also explored.
1 - Sam Houston State University, Department of Biological Sciences, 1900 Avenue I, Huntsville, TX, 77340, USA
2 - Baylor University, Department of Environmental Studies, Waco, TX, 76798-7266, USA
Session: 34
Location: Room 6/Woodward
Date: Tuesday, July 29th, 2008
Time: 11:45 AM
Number: 34015
Abstract ID:373

Hawkins, Angela [1], Randle, Christopher P. [2].
A preliminary examination of subspecific classification within Phoradendron serotinum (Santalaceae): development of microsatellite markers for assessment of population genetic structure.
Phoradendron serotinum, (leafy mistletoe) is a hemi-parasitic plant of the family Santalaceae found in the United States and Mexico.  P. serotinum has been divided into four subspecies: subsp. tomentosum, subsp. macrophyllum and subsp. serotinum which occur in the eastern United States from southern New Jersey to southern Florida, through the Midwest south of Oklahoma and into Mexico, and on the west coast from Oregon to Baja, California. Subspecies angustifolium grows in isolated regions of Central Mexico. Subspecies may be difficult to identify based on morphology alone. For instance subspecies serotinum is distinguished from the others by the presence of lightly puberulent leaves (opposed to glabrescent to short pubescent). Just within subspecies serotinum leaves can be elongated, obovate or spathulate (opposed to elliptical, ovate, or orbicular for the other three subspecies). This overlap is especially evident in eastern Texas as these characters that may otherwise be diagnostic of subspecies do not adequately separate three of the subspecies (macrophyllum, tomentosum, and serotinum) that grow in this region. Molecular and morphometric analyses are being utilized to resolve taxonomic confusion within Phroadendron serotinum. Total genomic DNA has been isolated from fresh tissue of more than 100 Phoradendron serotinum samples from three areas in Texas (Huntsville, College Station, and Del Rio). Microsatellite regions have been isolated using a hybridization-capture method. Twelve potential primer sequences have been identified and will be used in future molecular assessments. Additional specimens will be collected from the remainder of species distribution and sampled for genetic differentiation. Ultimately, we hope to provide genetic evidence for classification that will be used in conjunction with morphology.
1 - Sam Houston State University, Department of Biology, 1900 Avenue I, Huntsville, Texas, 77340, US
2 - Sam Houston State University, Department of Biological Sciences, 1900 Avenue I., Huntsville, TX, 77340
Session: P
Location: Ball Room & Party Room/SUB
Date: Monday, July 28th, 2008
Time: 12:30 PM
Number: PRT026
Abstract ID:1153

Ross Friedman, Cynthia [1].
Immunolocalization of aquaporins in the fruit of the dwarf mistletoe Arceuthobium americanum (Viscaceae).
Dwarf mistletoes (genus Arceuthobium) are dioecious, hemiparasitic angiosperms. In British Columbia (BC), the dwarf mistletoe A. americanum Nutt. ex Engelm. parasitizes lodgepole pines (Pinus contorta), and seriously compromises the health of BC pine forests. All dwarf mistletoes disperse their seeds by a remarkable process of explosive discharge, allowing further parasitism of the original host as well as infestation of neighboring trees. Through multiple infections, A. americanum will ultimately kill its host. To better understand dwarf mistletoe pathology, elucidation of the discharge process at the cellular level is critical. Previous work has shown that the generation of a large hydrostatic pressure within the dwarf mistletoe fruit will trigger the discharge. Many independent studies have established that aquaporins, highly-conserved integral membrane proteins, play a pivotal role in facilitating water movement within plant tissues. As such, we suspected that aquaporins are involved in the generation of water pressure within the fruit. Therefore, we wanted to see if aquaporins were present in the dwarf mistletoe fruit. To do this, we obtained an antibody against a tobacco (Nicotiana tabacum) plasma membrane aquaporin (Plasma membrane Intrinsic Protein I) that had been raised in a rabbit. Ultrathin LR White sections were obtained from fruit at two stages of development – three months and one month prior to explosive discharge. The sections were then subjected to immunocytochemistry and transmission electron microscopy. Preliminary results indicate that the anti-tobacco aquaporin antibody does cross-react with putative aquaporin(s) in the dwarf mistletoe fruit. More work, including statistical analysis, is required to determine which tissue(s) and which stages of development exhibit greater degrees of binding.
1 - Thompson Rivers University, Department of Biological Sciences, Box 3010, 900 McGill Road, Kamloops, BC, V2C 5N3, Canada
Session: 33
Location: 215/SUB
Date: Tuesday, July 29th, 2008
Time: 10:30 AM
Number: 33010
Abstract ID:701

Koziura, Karl J [1], Ross Friedman, Cynthia [1].
Do extracts from dwarf mistletoe (Arceuthobium, Viscaceae) affect the viability of salmon cells in tissue culture?
The lodgepole pine dwarf mistletoe, Arceuthobium americanum Nutt. ex Engelm., is a parasitic plant that lives on lodgepole pine (Pinus contorta) in British Columbia. This small plant obtains nutrients from its host at a great rate. The parasite disperses its seeds by explosive discharge, which allows further parasitism of the original host as well as spread to neighboring trees. Through multiple infections, A. americanum will be detrimental to the host, and can eventually kill it. Recent research at Thompson Rivers University has shown that a methanolic extract of A. americanum has antibacterial activity. Upon initial purification, the antibacterial activity separates into a “6 methanol: 4 water fraction” (as opposed to a “hexanes” fraction). The objective of the work presented here is to determine what effects the antibacterial “6: 4 fraction” has on animal cells, and to compare these with a non-antibacterial “hexanes” fraction. Salmon epithelial cells in 1mL tissue culture were exposed to 2.5, 5.0, or 7.5mg of either the “6:4” or the “hexanes” fraction. An apoptosis test was performed on the cells after exposure to the fractions for 1 hour. Necrosis was not substantially triggered by the “6:4” nor the “hexanes” fraction, although the “hexanes” fraction induced more necrosis than the “6:4” at higher dosages. Both fractions induced apoptosis as dosage increased, but the “hexanes” fraction induced apoptosis at a lower dosage than the “6:4.” More work is needed to elucidate if the antibacterial compound(s) in the “6:4” and those inducing apoptosis are the same.
1 - Thompson Rivers University, Department of Biological Sciences, Box 3010, 900 McGill Road, Kamloops, BC, V2C 5N3, Canada
Session: 57
Location: 211/SUB
Date: Wednesday, July 30th, 2008
Time: 8:45 AM
Number: 57002
Abstract ID:628

Ross Friedman, Cynthia [1], More, Fawna N. [1].
Effect of male dwarf mistletoe (Arceuthobium americanum) infection on the potential antimicrobial properties of lodgepole pine (Pinus contorta var. latifolia.
Arceuthobium americanum (dwarf mistletoe) is a hemi-parasitic flowering plant that infects lodgepole pine in western North America. This small pest is generally regarded as a big problem in British Columbia (BC) forests, because it reduces the yield of timber and compromises forest productivity. However, our lab recently discovered that a methanolic extract from dwarf mistletoe possesses antimicrobial activity against Gram-positive bacteria, including Staphylococcus aureus and Methicillin-resistant S. aureus (MRSA). Furthermore, while little research has explored the antimicrobial properties of lodgepole pines, others have shown that extracts obtained from conifer bark and needles from various Old World Pinaceae have antimicrobial properties, and have been used in Austria for centuries to treat various ailments. Here, we hypothesized that the lodgepole pine needle extracts would have antimicrobial properties, and that needles from dwarf mistletoe infected pines would have enhanced antibiotic activity. We used needle extracts from both infected and uninfected lodgepole pines to challenge medically-relevant Gram-positive (S. aureus,  MRSA and Bacillus species) and Gram-negative (E. coli, and Klebsiella pneumoniae) bacteria via pour plate bioassays; antimicrobial activity of various extracts was determined by measuring the zones of inhibition on different plates. Preliminary evidence suggests that conifer needles from mistletoe-infected pines do not display enhanced antimicrobial activity when infected with dwarf mistletoe, as opposed to either extract alone. With the overuse and improper use of antibiotics to treat common disease, new strains of bacteria are created. New natural antibiotics or antimicrobial agents must be made to prevent an epidemic of antibiotic resistant bacteria. We propose that extracts from conifers infected with dwarf mistletoe could be further developed as a natural “plantibiotic.”
1 - Thompson Rivers University, Department of Biological Sciences, Box 3010, 900 McGill Road, Kamloops, BC, V2C 5N3, Canada
Session: 57
Location: 211/SUB
Date: Wednesday, July 30th, 2008
Time: 8:30 AM
Number: 57001
Abstract ID:474

Mason, Quinn [1], Ross Friedman, Cynthia [1].
Extraction, Partial Purification and Susceptibility Testing of a Potentially Novel Antibiotic from Lodgepole Pine Dwarf Mistletoe (Arceuthobium americanum).
A. americanum is a dioecious parasitic plant that infects lodgepole pine in British Columbia. It is considered a forest pest and causes the trees to grow in an unsymmetrical manner resulting in reduced wood quality and ultimately lost revenue to the forest industry. As such, it was previously thought that there was no benefit to its presence, however previous work identified a methanolic extract from the plant that showed antimicrobial activity against Gram-positive bacteria. Misuse of antibiotics has resulted in the emergence resistant bacteria with unsurpassed adaptability to modified antibacterial agents. The continual appearance of these pathogens has resulted in a constant need for novel antibiotics. Here, we demonstrate a basal purification protocol that removes many inactive components of the raw extract and serves to concentrate the active portion. This theory was supported experimentally by an observed increase in antimicrobial activity measured via a disc-diffusion bioassay at fixed concentrations as the purification procedure progressed. In order to explore the spectrum of this antimicrobial we performed susceptibility tests on various medically relevant microorganisms and found the extract to be active against a narrow range of Gram positive bacteria only. This is a promising result as the development of antibiotic resistance and secondary infection is slowed or halted by destroying only the pathogenic organisms. Narrow spectrum antibiotics target only specific bacteria and limit collateral damage to natural flora. These findings represent a possible beneficial property of an otherwise solely detrimental forest pest.
1 - Thompson Rivers University, Department of Biological Sciences, Box 3010, 900 McGill Road, Kamloops, BC, V2C 5N3, Canada
Session: 57
Location: 211/SUB
Date: Wednesday, July 30th, 2008
Time: 9:15 AM
Number: 57004
Abstract ID:619

Parasitic Plants, General

Vazquez-Garcia, J. Antonio [1], Chazaro-Basañez, Miguel de J. [2], González-Gallegos, Jesús G. [1].
Floristic and phytogeographical patterns of parasitic species in Mexico.
Trends in species richness, composition and speciation of vascular parasitic communities in Mexico were examined along a latitudinal gradient of over 17 degrees of latitude. Each state in Mexico represented a plant parasitic community. Four matrices with presence/absence data were used. Bray-Curtis technique was used in connection with the Sorensen distance and the sociological favorability index (Beals Smoothing). Direct gradient analysis in connection with regression analyses were also used to determine whether species richness of certain parasitic communities could be explained by latitude or altitude. Throughout a matrix on generic richness among various entities abroad, phytogeographical relationships were examined as well as the influence of Boreal versus Neotropical elements. 1) At the national scale 383 species, three subspecies and 40 genera and 17 families were inventoried for the first time. Mexico showed an extraordinary species richness of vascular parasitic flora from 22 to 40 % greater than expected at the international scale, perhaps due to its unique location in the transition between Holartic and Neotropical realms. Santalales and Scrophulariales, Scrophulariaceae and Viscaceae and the genera Phoradendron, Castilleja and Cuscuta were the most diverse taxa on their category. Aerial (stem) parasites were comparable in richness to that to terrestrial (root) parasites. Over two thirds of the parasitic flora were hemi-parasites and close to one third included holoparasites. 2) Direct (bivariate ordination) showed that latitude explained species richness of Loranthaceae sensu stricto only, while indirect (multivariate) ordination showed that Loranthaceae sensu lato (Loranthaceae and Viscaceae) could also be explained by the latitude. These data suggest the existence of a critical bioclimatic zone between 3000 and 3500 m in elevation where the richness of three of the prominent genera of Viscaceae and Loranthaceae declined drastically.
1 - Universidad de Guadalajara-CUCBA, Botanica y Zoologia (Instituto de Botanica)., Km. 15.5, Las Agujas, Nextipac., Zapopan, Jalisco, 45110, MEXICO
2 - Universidad de Guadalajara-CUCSH, Geografia y Ordenacion Territorial, Guanajuato 1045, Avenida de los Maestros y Mariano Bárcena, puerta, Guadalajara, Jalisco, 44260, MEXICO
Session: P
Location: Ball Room & Party Room/SUB
Date: Monday, July 28th, 2008
Time: 12:30 PM
Number: PSP043
Abstract ID:875


SIUC / College of Science / Parasitic Plant Connection
URL: http://www.parasiticplants.siu.edu/meetings/Bot2008ParAbstracts.html
Last updated: 11-Aug-08 / dln