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