Orobanchaceae
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.
Santalales
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.
Mycoheterotrophs
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.