Wolfe, Andrea 
Assessing the host range of Hyobanche
(Orobanchaceae) using DNA forensics.
Hyobanche L. is a small genus
of holoparasitic plants distributed across southern Africa. It is found
in a variety of ecosystems ranging from coastal sand dunes to fynbos
biomes, the Little and Great Karoos, and into the highlands Lesotho.
Hyobanche is a root parasite with an unique system of secondary
haustoria formed on the leaf bracts of the rhizomes, which can be quite
an extensive system underground. Proximity to other plants is not a
good indicator of the actual host plant being parasitized. To determine
the host range for species of Hyobanche
ca. 400 host roots attached to haustoria were collected and their DNA
extracted. Accessions with amplifiable DNA were sequenced and matched
to sequences deposited into Genbank or to sequences obtained from
potential host plants collected in proximity to parasitic plants
collected in the field. Hyobanche
parasitizes a wide range of plant genera from Asteraceae, Goodeniaceae,
Poaceae, and Thymelaeaceae, and multiple plant genera may be
parasitized at the same time.
1 - Ohio State University, Department of Evolution, Ecology, and
Organismal Biology, 318 W. 12th Avenue, Columbus, OH, 43210-1293, USA
Rodrigues, Anuar , Colwell, Alison , Stefanovic, Sasa .
Phylogeny of the parasitic genus Conopholis (Orobanchaceae): Evidence from plastid and nuclear DNA sequences.
Little is known of the evolutionary relationships among populations and species of Conopholis, a small holoparasitic genus with reduced vegetative morphology. In the most recent taxonomic classification of this genus, Conopholis is described as having two species, C. americana and C. alpina.
This classification is based on a combination of presence/absence of
characters along with a number of quantitative traits. We conducted the
first phylogenetic study of Conopholis
designed to develop a resolved and well-supported multi-locus
phylogenetic hypothesis for this genus. We analyzed plastid (trnfM-E
intergenic spacer and clpP gene/introns) and nuclear (phyA intron 1)
nucleotide sequence data using the neighbor-net, Bayesian, and
parsimony approaches in addition to conducting tests of alternative
hypotheses. Our data set contained populations from a wide taxonomic
sampling covering its entire geographical range in North America. The
results indicate that regardless of the data set used or phylogenetic
methodology employed, none of our analyses lend support for the strict
subdivision of the genus into the two currently recognized species.
Instead, three distinct genetic clusters were recovered and indicates
that reciprocal monophyly between the two currently accepted species
has not yet been achieved. Conopholis alpina is paraphyletic and shows evidence of belonging to at least two separate lineages. The monophyly of C. americana
was also not recovered; however, this possibility could not be rejected
with confidence. These analyses recovered three distinct lineages
indicating that there could be a minimum of three species within the
genus. We anticipate that a fine-scale morphometric analysis of
morphological features within Conopholis may reveal shared features that could further corroborate our molecular results.
1 - Univeristy of Toronto Mississauga, Biology, 3359 Mississauga Road North, Mississauga, ON, L5L 1C6, Canada
2 - Division of Biological Resources, Yosemite National Park, El Portal, CA, 95318, USA
3 - UNIVERSITY OF TORONTO, Department Of Botany, 3359 MISSISSAUGA RD N, MISSISSAUGA, ON, L5L 1C6, Canada
Morawetz, Jeffery .
Haustorial structural diversity across parasitic Orobanchaceae.
Orobanchaceae present an ideal system for studying evolution of the
parasitic habit in flowering plants: with a single origin of
parasitism, the full range of trophic modes is represented, from
non-parasites to facultative and obligate hemiparasites and
holoparasites. This parasitic ability is conferred through an organ
unique to parasitic plants: the haustorium. The Orobanchaceae are
parasitic on the roots of their host plants through terminal and/or
lateral haustoria that develop along the parasite's root system.
Haustoria have a generalized internal structure, being composed of a
vascular core, hyaline body, and endophyte, often with a bridge of
xylem cells connecting the vasculature of host and parasite. Reports of
phloem connections between host and parasite in Orobanchaceae are rare,
and detailed comparative studies of haustorial structure within and
across the main parasitic lineages of the family are lacking.
Haustoria, representing four of five parasitic lineages within the
family, were collected from plants excavated in the field, and were
subsequently embedded in paraffin and plastic for structural
examination. Xylem bridges were observed in all taxa examined. The
proximity of parasite and host phloem, and the presence of parenchyma
including transfer cells at the host-parasite interface were variable,
and characteristics of these elements will be further discussed. What
are the structural modifications involved in phloem-to-phloem transfer
between the host and parasite in Orobanchaceae and does this include
direct sieve element connections?
1 - Rancho Santa Ana Botanic Garden, 1500 North College Ave., Claremont, CA, 91711, USA
Wickett, Norman J , Honass, Loren , Wafula, Eric , Timko, Michael , Westwood, James , Yoder, John , de Pamphilis, Claude W .
Using stage specific cDNA sequencing to uncover the origin and evolution of parasitism in Orobanchaceae.
The Parasitic Plant Genome Project is a collaborative effort to use
stage specific cDNA sequences to understand the genomic changes that
led to, and resulted from, the acquisition of a parasitic life history
in Orobanchaceae. Transcriptomes of three Orobanchaceae species that
vary in their nutritional strategies were sequenced using both 454 and
Illumina technologies: the facultative hemiparasite Triphysaria versicolor, the obligate hemiparasite Striga hermonthica, and the holoparasite Orobanche (Phelipanche) aegyptiaca.
Within each species, transcriptomes were sequenced from multiple
developmental stages from germinating seeds, to early attachment to
host, to above-ground reproductive and vegetative tissues. Using this
comparative framework, we are developing a set of genes that may play
an important role in haustorium formation (a parasitic plant specific
organ that is used to invade the host plant), host invasion, and
nutrient acquisition. Additionally, these data are being used to test
hypotheses of molecular evolution and to explore the history of
polyploidy in this lineage.
1 - Penn State University, Biology, 403 Life Sciences Building, University Park, PA, 16802, USA
2 - Penn State University, Biology, 403 Life Science Building, University Park, PA, 16802, USA
3 - University of Virginia, Biology, Gilmer Hall 044, PO Box 400328 , Charlottesville, VA, 22904-4328, USA
4 - Virginia Tech, Plant Pathology, Physiology, and Weed Science, 401 Latham Hall (0390), Blacksburg, 24061, VA, USA
5 - University of California, Davis, Plant Sciences , Mail Drop 3 , 137 Asmundson Hall, Davis, CA, 95616, USA
6 - Pennsylvania State University, Department Of Biology, 101 LIFE SCIENCES BUILDING, UNIVERSITY PARK, PA, 16802, USA
Santalales - Viscaceae
Cannon, Brandi , Garrison, Jessica , Sopas, James , Verastegui, Timothy , Randle, Christopher .
Presentation, aroma, and flavor: Investigation of host cues in the orientation and establishment of Phoradendron serotinum (Viscaceae).
Obligate parasitic plants cannot survive without the influx of water
and/or nutrients from host plants. Therefore, successful establishment
of haustoria (vascular organs of penetration and transport) is
necessary for the survival of an emerging seedling. Extensive studies
have been performed on the effect of host cues on germination,
orientation, and development of haustoria in root parasites. For root
parasites, host cues must be transmitted through the rhizosphere and
are largely chemical. Plants that are parasitic on the aboveground
stems of host plants must be able to detect hosts in a much different
milieu. Phoradendron serotinum (leafy mistletoe) is a water parasite of broadleaf trees. While P. serotinum
parasitizes many different hosts across its range, populations are most
often locally host specific, preferring a single host even when other
hosts are available. The underlying cause of this pattern of host
preference is unknown, and will remain so until host cues responsible
for successful establishment of haustoria have been identified. In this
study, we examined the effects of light cues, physiochemical cues
associated with the host surface, and gaseous chemical cues on the
viability, orientation, and successful establishment of emerging
haustoria on host plants. Light and physiochemical cues associated with
the host substrate had a significant effect on haustorial
establishment. Gaseous cues had a significant positive effect on
viability and orientation. This latter result was foreshadowed by a
similar finding in the stem parasite Cuscuta, which responds to gaseous cues emitted by host plants.
Caraballo-Ortiz, Marcos , Carlo, Tomas .
Coevolution of American mistletoes with tree families. Poster
Mistletoes are obligate parasitic plants that depend on host trees for
their establishment, growth, and mineral nutrition. Although mistletoes
play an important ecological role in plant communities, little is known
about the coevolution between mistletoes and their hosts. To determine
if mistletoes are host specific (a measure of coevolution), we selected
the two largest mistletoe families in America (Loranthaceae and
Viscaceae) and assembled a database using thousands of parasitism
records from herbarium specimens and the literature. Next, we compared
the frequency of host parasitism among the most common tree families
and genera present in the Americas. We found that mistletoe parasitism
is not random across plant families, and although parasitism has been
recorded in more than 100 tree families, mistletoes were significantly
more frequent in families such as Leguminosae, Fagaceae, Malvaceae,
Rutaceae, and Pinaceae. To gain insight in the level of host
specificity, we performed a reciprocal transplant experiment in the
field using mistletoes in the genus Dendropemon (Loranthaceae). We carried out the experiment in Northeastern Puerto Rico where two very similar Dendropemon species coexist in different host trees: D. bicolor in Tabebuia (Bignoniaceae) and D. caribaeus in Citharexylum (Verbenaceae). The results of the reciprocal transplant suggest that Dendropemon
mistletoes are host specific. These data also suggest that the global
pattern of coevolution between mistletoes and their hosts is influenced
by the taxonomic identity and the local interactions of both the
parasite and its host.
1 - Penn State University, 208 Mueller Lab, University Park, PA, 16802, USA
Braukmann, Thomas , Stefanovic, Sasa .
Comparative plastid genome evolution in mycoheterotrophic Ericaceae.
Heterotrophic plants exhibit a wide range of evolutionary degradation
of photosynthetic ability and rely entirely or partially on their hosts
to supply water and nutrients. These plants are divided into two
distinct, but evolutionary artificial groups, parasitic and
mycoheterotrophic plants. Haustorial parasitism has evolved at least 11
times independently and there are at least 10 independent origins of
mycoheterotrophy in angiosperms. Each lineage represents an independent
origin of heterotrophy and heterotrophs are not well characterized
outside a few well-studied examples. Ericaceae, the heather family, is
a large and diverse group of plants with elaborate symbiotic
relationships with mycorrhizal fungi, including several
mycoheterotrophic lineages. Grounded within a phylogenetic framework
and broad taxonomic sampling, a comparative investigation of plastid
genomes was conducted in the family usinga slot-blot Southern
hybridization approach. This survey contained lineages within Ericaceae
with different life histories and trophic levels, including multiple
representatives from the hemi-mycoheterotrophic pyroloids and
holo-mycoheterotrophic monotropoids. A number of fully photosynthetic
(autotrophic) members were included to best represent the other major
clades within Ericaceae. This survey used 55 probes derived from all
categories of protein-coding genes typically found inthe plastomes of
photosynthetic plants. Our results indicate that monotropoids exhibit
extensive loss off genes relating to photosynthetic function and retain
genes with possible function outside photosynthesis. Furthermore,
hemi-mycoheterotrophic plants retain most genes relating to
photosynthesis but are polymorphic for the plastid ndh genes. Our
survey extends previous inferences that plastid gene losses occur prior
to becoming holo-heterotrophic and that mycoheterotrophic Ericaceae
exhibit gene losses similar in pattern to parasitic plants.
1 - University Of Toronto At Mississauga, Department Of Biology, 3359 Mississauga Rd N, Mississauga, ON, L5L 1C6, Canada
Bowler, Rebecca , Fredeen, Arthur , Massicotte, Hugues .
Investigation of carbon gain of autotrophic, mixotrophic and
myco-heterotrophic species at three sites in north-central British
Most terrestrial vascular plants rely to some degree on mycorrhizal
fungi for obtaining mineral nutrition. A subset of these plants also
rely on their mycorrhizal partner(s) for some (mixotrophy) or all/most
(myco-heterotrophy) of their carbon. Many pyroloids (Pyroleae tribe of
the Ericaceae family) and some green orchids (Orchidaceae) are
mixotrophs. By contrast, leafless orchids of the genus Corallorhiza
are thought to be exclusively myco-heterotrophic. We conducted a pilot
project where we assessed the photosynthetic competence of autotrophic,
mixotrophic and myco-heterotrophic species growing in sub-boreal
forests of north-central British Columbia. Gas exchange properties of
each species were non-destructively measured in situ at least once a
month during the growing season (May to September) of 2011 using a
portable gas exchange system (model LI-6400, LiCor Inc.). Individuals
of these species were also replanted in the Enhanced Forestry Lab at
UNBC for further analysis. After approximately one month of acclimation
to non-forest light levels, light response curves of each sample were
measured using the same methods as in situ measurements with the
exception of an artificial light source. We will highlight the current
implications of our results and our future plans for this study.
1 - University Of Northern British Columbia, Ecosystem Science And
Management Program, 3333 University Way, Prince George, BC, V2N 4Z9,
Broe, Michael , Freudenstein, John .
Monotropa hypopithys L. (Ericaceae) is a distinct genus with well-defined species segregates at the molecular level.
The Monotropoideae are a herbaceous, achlorophyllous subfamily of the
Ericaceae, within which 12 species in 10 genera are currently
recognized. Most species are endemic to North America, however two---Monotropa uniflora L. and Monotropa hypopithys
L.---have a much wider distribution in the Americas and Eurasia. We
performed an extensive sampling of monotropoids across N. America, and
here present molecular evidence for a revised treatment of this group
based on ITS1, ITS2 and 26S (approx. 1200 bp). While the two Monotropa
have long been recognized as a single genus, the phylogeny we present
strongly supports the recognition of two distinct genera. Hypopitys (M. hypopithys) forms a monophyletic group with Pityopus, while Monotropa sensu stricto (M. uniflora) forms a monophyletic assemblage with Monotropsis and Monotropastrum (Asia). Hypopitys and Monotropa are further separated by the intervening genera Allotropa and Hemitomes. Within Hypopitys
itself species and sub-species have been erected and subsequently
synonymized to a remarkable degree. Small recognized five species in N.
America, while in the most recent monograph Wallace rejected all such
distinctions, choosing to synonymize some 80 putative species,
subspecies and varieties in the Americas and Europe, noting 'there are
no segregates that yet warrant taxonomic recognition'. Our analysis
reveals five geographically circumscribed clades of Hypopitys
in N. America alone---although the pattern is only partially congruent
with Small's analysis---as well as a distinct Eurasian clade. This
contrasts markedly with Monotropa, which exhibits no such structure in N. America at this level of phylogenetic resolution.
1 - The Ohio State University Herbarium, Evolution, Ecology and Organismal Biology, 1315 Kinnear Rd, Columbus, OH, 43212, USA