Abstracts Dealing with Parasitic Angiosperms and Mycoheterotrophs
Botany 2010
Rhode Island Convention Center, Providence, RI

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Cameron, Duncan D [1], Těšitel, Jakub [2].

How parasitic are hemiparasitic plants? Estimating heterotrophic carbon gain by Rhinanthus minor and Euphrasia rostkoviana (Orobanchaceae).

Hemiparasitic plants gain virtually all mineral nutrients and water from their host plant while organic carbon is provided, at least in part, by their own photosynthetic activity although their rates of assimilation are substantially lower than that found in non-parasitic plants. Hence, hemiparasites must gain at least some of their organic carbon heterotrophically from the host plant. Despite this, heterotrophic carbon gain by root hemiparasites has been investigated only for a few genera. We investigated heterotrophic carbon gain by two root hemiparasites Rhinanthus minor L. and Euphrasia rostkoviana Hayne (Orobanchaceae) using natural abundance stable isotope (δ13C) profiles of both parasites attached to C3 (wheat) and C4 (maize) hosts coupled to a linear two-source isotope mixing model to estimate the percentage of carbon in the parasite that was derived from the host. Both R. minor and E. rostkoviana attached to maize hosts were significantly more enriched in 13C than those attached to wheat hosts with R. minor becoming more enriched in 13C than E. rostkoviana. The natural abundance 13C profiles of both parasites were not significantly different from their wheat hosts but were less enriched in 13C than maize hosts. Using a linear two-source isotope mixing model we estimated that R. minor and E. rostkoviana adult plants derive c. 50 and 25% of their carbon from their hosts respectively. In light of these results, we hypothesize that repeatedly observed negative effect of competition for light on hemiparasites acts predominantly in early ontogenetic stages when parasites grow unattached or the abstraction of host nutrients in less effective.
1 - University of Sheffield, Department of Animal and Plant Sciences, Alfred Denny Building, Western Bank, Sheffield, South Yorkshire, S10 2TN, UK
2 - University of South Bohemia, Department of Botany, Ceske Budejovice, Czech Republic
Keywords: Heterotrophy maize Parasitism wheat 13C.

Fisher, James P [1], Phoenix, Gareth K [1], Cameron, Duncan D [2].

Robbing the rich to feed the rich? The direct and indirect effects of a parasitic plant on nutrient cycling and community structure.

Rhinanthus minor is a root-hemiparasite known to induce dramatic shifts in the composition of grassland communities in which it occurs. By decreasing the proportion of grasses in a community, this parasite allows forb species (non-leguminous dicots) to proliferate under reduced competition. This shift is underpinned by the differential ability of the plant functional groups to resist parasitism; grasses exhibit a weak resistance response while forbs resist parasitism strongly. In addition to their direct effects, parasitic plants can also have indirect effects on their host communities by modifying the flux of nutrients through ecosystems. Specifically, R. minor can extract nutrients from its perennial hosts and return them to the soil via its nutrient rich litter. But do these liberated nutrients act to ameliorate the direct impact of parasitism on susceptible hosts or further benefit the resistant ones? Do all species or functional groups within a grassland community benefit equally from the R. minor induced nutrient flush? In 2005 we established a field experiment in Derbyshire, UK to address these questions. Four treatments; (i) infection by R. minor, (ii) treatment with R. minor litter, (iii) infection by R. minor plus litter treatment and (iv) control, were applied to 40 1.25x1.25m plots. In August 2009 a vegetation survey was undertaken and followed by an above-ground harvest. Biomass, tissue N and tissue P were determined for each functional group (grasses, fobs and legumes) within each plot. The vegetation survey revealed a clear impact of R. minor infection on community composition; with the first evidence that parasitic plant litter can have differential effects on discrete functional groups within natural plant communities in the field. Moreover, in grasses, the positive effects of litter inputs negated the negative effects of parasitims .
Therefore, to understand the role that parasitic plants play in modulating plant community structure we must consider both their direct parasitic effects and their indirect impacts on nutrient cycling.
1 - University of Sheffield, Department of Animal & Plant Sciences, Western Bank, Sheffield, South Yorkshire, S10 2TN, UK
2 - University of Sheffield, Department of Animal and Plant Sciences, Alfred Denny Building, Western Bank, Sheffield, South Yorkshire, S10 2TN, UK
Keywords: Parasitic plants Community structure Plant litter Nutrient cycling Rhinanthus minor.

Latvis, Maribeth [1], Moore, Michael [2], Wicke, Susann [3], Soltis, Pamela S. [4], Soltis, Douglas E.  [5].

How do different forms of parasitism within a family affect plastid genome structure? A comparison of the complete plastid genomes of Lindenbergia, Agalinis, and Epifagus (Orobanchaceae). TALK CANCELED

With few exceptions, chloroplast genome structure is remarkably conserved across the diversity of angiosperms, in part due to strong selective pressures on the photosynthetic machinery housed in these organelles. Parasitic plants, in deriving some or all of their nutrition from other plants, provide a well-documented exception to this rule because of relaxed functional constraints. The family Orobanchaceae has long been recognized as an ideal system to explore these modifications associated with the acquisition of a parasitic lifestyle, as the clade contains species of all trophic levels, including the autotroph Lindenbergia, facultative and obligate hemiparasites, and several independently derived holoparasitic lineages. The majority of research in Orobanchaceae has focused on chloroplast genome reduction and modification in holoparasites, which lack chlorophyll, have reduced leaves, and represent the non-photosynthetic extreme of parasitic ability. In contrast, little is known about hemiparasites of this clade, those that retain chlorophyll, are photosynthetic, and otherwise appear “normal.” Here, we present the complete chloroplast genome sequences of the hemiparasite Agalinis fasciculata and autotrophic Lindenbergia philippensis, in comparison with previously published data for the holoparasite Epifagus virginiana, and characterize patterns of gene loss, modification and nucleotide substitution. As the only autotrophic lineage of Orobanchaceae and sister to the rest of the family, Lindenbergia is crucial for rooting further comparative genomic studies in the clade.
1 - University of Florida, Florida Museum of Natural History, Dickinson Hall, Gainesville, Florida, 32611, USA
2 - Oberlin College, Biology Department, 119 Woodland Street, Science Center K111, Oberlin, Ohio, 44074-1097, USA
3 - University of Vienna, Department of Biogeography, Rennweg 14, Vienna, Vienna, A-1030, Austria
4 - University of Florida, Florida Museum of Natural History, Museum Road and Newell Drive, Dickinson Hall, Gainesville, FL, 32611-7800, USA
5 - University of Florida, Department of Biology, 220 Bartram Hall, P.O. Box 118526, Gainesville, FL, 32611, USA
Keywords:  Orobanchaceae chloroplast genome  Parasitism Agalinis Lindenbergia Epifagus next-generation sequencing.

Li, Jianhua [1], Corajod, Jeffrey [1], Deyoung, Jeffrey [1].

Host preferences of Beechdrops (Epifagus): evidence from chloroplast DNA sequence data.

In nearly two hundred years, botanists and the general public have assumed that Epifagus virginiana (beechdrops) parasitizes specifically on the roots of Fagus grandifolia (American beech tree). In this study we used sequences of the chloroplast gene rbcL from host roots of beechdrops to test the long-held theory. Host roots on which Epifagus grows were randomly collected from four localities in western Michigan. Our data show that although roots of maple and beech are intricately interwoven with the grappler roots of Epifagus, all of our root samples for which we verified the host-parasite direct connections under dissecting microscope were from American beech trees (Fagus grandifolia) except for one from Acer saccharum. The potential beechdrop-sugar maple relationship needs further verification from physiological investigations. Therefore, our DNA sequence data support the host preference of Epifagus on roots of Fagus and suggest that parasite-root interactions may be complex and DNA barcoding can be useful for studying the host preference of parasitic plants.
1 - Hope College, Biology Department, 35 E 12th St., Holland, MI, 49423, USA
Keywords: Epifagus Chloroplast DNA sequence host-parasite.

Wicke, Susann [4], Quandt, D. [1], Muller, Kai F. [2], Wickett, Norman J. [3], dePamphilis, Claude W. [3], Schneeweiss, Gerald M. [4].

Plastid Genome Evolution - What’s so different between autotrophs, semi- and non-autrophic flowering plants?

The plastid genome is known to be highly conserved among flowering (and land) plants. The present work illustrates the conserved evolution of the angiosperm plastome in a phylogenetic framework comparing genome structure and evolution in nearly all major lineages of angiosperms. As a group of plants that exhibit major changes in plastid genome structure, both semi- and non-autotrophic plants will be discussed in order to explore and understand the subtle but continuous reduction of genomes under relaxed evolutionary constraints. The transition from a fully autotrophic way of life towards a complete heterotrophic lifestyle (i.e. complete loss of photosynthesis) via various levels of semi-autotrophy severely affects plastome stability and evolution. In the present study, plastid genomes from several hemiparasitic and holoparasitic representatives of the broomrape family (Orobanchaceae) have been sequenced and analyzed with respect to co-linearity, gene content, pseudogenization and substitution rates. One focus is the rate heterogeneity among distinguished gene classes, single genes and gene operons, as well as the evolution of non-protein coding plastome fractions. Relaxation of evolutionary constraints appears to occur much earlier during the evolution of parasitism than previously assumed and strongly affects structural integrity of distinct plastome fragments.
1 - Rheinische Friedrich-Wilhelms-Universität, Nees-Institut für Biodiversität der Pflanzen, Meckenheimer Allee 170, D-53115, Bonn, Germany
2 - Westfälische Wilhelms-Universität, Institute for Evolution and Biodiversity, Hüfferstrasse 1, Münster, 48149, Germany
3 - Pennsylvania State University, Department of Biology, 403 Life Sciences Building, University Park, Pennsylvania, 16802, USA
4 - University of Vienna, Biogeography and Botanical Garden, Rennweg 14, Vienna, A-1030, Austria
Keywords: plastid genome genome evolution pseudogenization rate heterogeneity parasitic plants hemiparasitic plants.

Wickett, Norman J. [1], Honaas, Loren A [1], Wafula, Eric K [1], Timko, Michael P [2], Yoder, John [3], Westwood, James [4], dePamphilis, Claude W. [5].

Exploring the causes and consequences of parasitism through stage specific transcriptome sequencing in the parasitic plant family Orobanchaceae.

Parasitic plants range in their nutritional dependence on their host from facultative, photosynthetic hemiparasites, through obligate hemiparasites, to non-photosynthetic, obligate holoparasites. Only one plant family, Orobanchaceae, comprises members of all three nutritional types. For this reason, Orobanchaceae is an ideal framework to study the molecular causes and consequences of the parasitic life history. As part of the Parasitic Plant Genome Project, we have sequenced stage specific cDNAs for multiple life history stages from three species of Orobanchaceae (Triphysaria versicolor, Striga hermonthica, and Orobanche aegyptiaca), representing three differing levels of host dependence. Twelve developmental stages for each species were targeted for sequencing and, currently, greater than 3 million 454 ESTs and 400 million paired-end Illumina ESTs have been sequenced. Initial assemblies of these data find between 43,361 and 50,899 unigenes of greater than 200bp in length. Putative unigene annotations were determined using a blastx search against ten fully sequenced plant genomes to assign each unigene to a scaffold of Tribes and Ortho groups (putative gene-families and clusters of orthologous genes, respectively) created for the PlantTribes database. Current assemblies and annotations place unigenes in 6124 to 6914 Tribes and 8946 to 10,056 Ortho groups. Here, we discuss the putative identities of sequenced transcripts with an emphasis on evolution of the photosynthetic apparatus and the development of a parasitic plant specific organ, the haustorium. Transcriptome data is also used here to investigate the role of genome duplication in the evolution of these parasites.
1 - Penn State University, Biology, 403 Life Sciences Bldg, University Park, PA, 16802, USA
2 - University of Virginia, Biology, Gilmer Hall 044, PO Box 400328, Charlottesville, VA, 22904, USA
3 - University of California-Davis, Plant Sciences, Davis, CA, 95616, USA
4 - Virginia Tech, Plant Pathology, Physiology and Weed Science, 410 Price Hall, Blacksburg, Virginia, 24061, USA
5 - Pennsylvania State University, Department of Biology, Institute of Molecular Evolutionary Genetics, and The Huck Institutes of the Life Sciences, University Park, Pennsylvania, 16802, USA
Keywords: parasitic plants transcriptome Solexa sequencing technology 454 sequencing EST.

Cuscuta (Convolvulaceae)

Bieber, Amanda [1], Wang H., Chak [3], Bolin, Jay F. [2], Tennakoon, Kushan U. [3], Musselman, Lytton John [4].

Molecular identification of potentially invasive Cuscuta in Brunei Darussalam.

A previously unidentified species of the parasitic plant genus Cuscuta (Convolvulaceae) is commonly found parasitizing plants in disturbed areas along roadsides in Brunei Darussalam, and has the potential to become a noxious weed. The plant is thought to spread by means of perennation, where new shoots form from thick coils at the end of the life cycle. Several populations have been observed since March 2008 and produced no flowers and thus, this apparently introduced species could not be identified. DNA sequence data from the nuclear ribosomal internal transcribed spacer (ITS) and chloroplast intron trnL-F was generated from silica-dried plant tissue. The Basic Local Alignment and Search Tool indicated that the introduced plant is closely related to Cuscuta australis. This species is widespread throughout Southeast Asia and is known to attack crops. One population in flower was subsequently discovered in November 2009, and has been tentatively identified as Cuscuta australis. Further phylogenetic study will be used to identify additional populations of Cuscuta in Brunei and infer the possible source of introduction. A recently formed collaboration between Old Dominion University and the University of Brunei Darussalam will provide further research opportunities of the genetic diversity of Cuscuta.
1 - Old Dominion University, Biology, 845 W. 43rd St., Norfolk, VA, 23508, USA
2 - Smithsonian Institution, Botany, DC, USA
3 - University of Brunei Darussalam, Department of Biology, Faculty of Science, Jalan Tungku Link,, Gadong, BE 1410, BRUNEI DARUSSALAM.
4 - Old Dominion University, Department of Biological Sciences, Mills Godwin Building, 45th Street, Norfolk, Virginia, 23529-0266, USA
Keywords: Cuscuta Convolvulaceae nuclear ribosomal ITS trnL-F perennation.


Hawkins, Angela K. [1], Randle, Christopher P. [1], Williams, Justin [1], Archambeault, Alan D. [1], Cannon, Brandi C.  [1].

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. Identification of P. serotinum subspecies in eastern Texas is especially difficult as characters that are otherwise diagnostic of subspecies do not adequately separate three of the subspecies(macrophyllum, tomentosum, and serotinum) that overlap in this region. Molecular and morphometric analyses were utilized in conjunction for a total evidence approach to resolve taxonomic confusion within P. serotinum. A subset of 96 samples of total genomic DNA, divided among 10 populations from the entire growth range, was analyzed over 6 microsatellite loci using GENEPOP. Morphometric measurements were recorded from 150 vouchers and analyzed by principal components analyses.
1 - Sam Houston State University, Department of Biological Sciences, 1900 Avenue I, Huntsville, TX, 77340, USA
Keywords: parasitic plants microsatellites population genetics Santalaceae.


Lam, Vivienne [1], Rai, Hardeep [2], Leebens-Mack, James H. [3], Givnish, Thomas J. [4], Davis, Jerrold I. [5], Stevenson, Dennis Wm. [6], Pires, J. Chris [7], Petersen, Gitte [8], Seberg, Ole [8], dePamphilis, Claude W. [9], Zomlefer, Wendy B [10], Ané, Cecile [11], Graham, Sean W. [12].

Retention of plastid genes in mycoheterotrophic monocots.

Mycoheterotrophy is a unique tripartite symbiosis between a heterotroph, autotroph and fungi, that in its most extreme cases has led to the loss of photosynthesis in the heterotrophic partner. It has arisen multiple times, but most abundantly in the monocots: mycoheterotrophs in Burmanniaceae, Corsiaceae, Iridaceae, Orchidaceae, Petrosaviaceae, Thismiaceae, and Triuridaceae comprise approximately 88% of all land-plant representatives. Consequences of the transition from a fully autotrophic to a mycoheterotrophic lifestyle are evident in the frequent loss and degradation of photosynthetic genes, such as the Rubisco large subunit (rbcL). Consequently, nuclear and mitochondrial sequence data are commonly used to place mycoheterotrophic in the broad backbone of plant phylogeny. However, retention of some essential, non-photosynthetic plastid genes provides an additional potential source of information on the phylogenetic placement of mycoheterotrophic plants, in addition to providing insights into plastome function and evolution. Our approach is to retrieve sequence data from residual plastid genes in these plants. So far, we have retrieved acetyl-coA (accD) and serine protease (clpP) genes for a range of non-orchid monocot mycoheterotrophs, and their green relatives. We have retrieved accD for mycoheterophic genera in the following families: Burmanniaceae (4 genera), Corsiaceae (1), Petrosaviaceae (1), Thismiaceae (2), and Triuridaceae (1), and have retrieved clpP from Burmanniaceae (2 genera), Petrosaviaceae (1), and Triuridaceae (1). We have also been successful at retrieving a number of additional non-photosynthetic and photosynthetic genes for Petrosavia sp. (Petrosaviaceae) and Burmannia capitata, further demonstrating that there may be a wealth of phylogenetically informative plastid data yet to be recovered from these elusive and enigmatic plants.
1 - University of British Columbia, UBC Botanical Garden and Centre for Plant Research, 6804 SW Marine Drive, Vancouver, BC, V6T 1Z4, Canada
2 - Harvard University, Arnold Arboretum, Harvard University Herbaria, 22 Divinity Avenue, Cambridge, MA, 02138, USA
3 - University of Georgia, Department of Plant Biology, 4504 Miller Plant Sciences, Athens, GA, 30602, USA
4 - University of Wisconsin Madison, Department of Botany, Birge Hall, 430 Lincoln Drive, Madison, Wisconsin, 53706-1381, USA
5 - Cornell University, L.H. Bailey Hortorium, Department of Plant Biology, Ithaca, New York, 14853, USA
6 - New York Botanical Garden, Institute of Systematic Botany, 200Th Street & Southern Boulevard, Bronx, New York, 10458-5126, USA
7 - University of Missouri Columbia, Biological Sciences, 1201 Rollins Road, Life Sciences Center 311, Columbia, Missouri, 65211, USA
8 - Natural History Museum of Denmark, Sølvgade 83, Opg. S, Copenhagen, DK-1307, Denmark
9 - Pennsylvania State University, Department of Biology, Institute of Molecular Evolutionary Genetics, and The Huck Institutes of the Life Sciences, University Park, Pennsylvania, 16802, USA
10 -
11 - University of Wisconsin-Madison, Department of Botany, 430 Lincoln Drive, Madison, WI, 53706
12 - University of British Columbia, Botanical Garden And Centre For Plant Research, 6804 Sw Marine Drive, Vancouver, British Columbia, V6T 1Z4, Canada
Keywords: mycoheterotrophy  Plastid Thismiaceae Burmanniaceae Petrosaviaceae Triuridaceae accD clpP Chloroplast gene evolution.

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URL: http://www.parasiticplants.siu.edu/meetings/Bot2010ParAbstracts.html
Last updated: 02-Aug-10 / dln