Claude W dePamphilis

Pennsylvania State University, University Park, Maryland, United States

Are you Claude W dePamphilis?

Claim your profile

Publications (114)842.44 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Movement of RNAs between cells of a single plant is well documented, but cross-species RNA transfer is largely unexplored. Cuscuta pentagona (dodder) is a parasitic plant that forms symplastic connections with its hosts and takes up host messenger RNAs (mRNAs). We sequenced transcriptomes of Cuscuta growing on Arabidopsis and tomato hosts to characterize mRNA transfer between species and found that mRNAs move in high numbers and in a bidirectional manner. The mobile transcripts represented thousands of different genes, and nearly half the expressed transcriptome of Arabidopsis was identified in Cuscuta. These findings demonstrate that parasitic plants can exchange large proportions of their transcriptomes with hosts, providing potential mechanisms for RNA-based interactions between species and horizontal gene transfer.
    Science (New York, N.Y.). 08/2014; 345(6198):808-11.
  • Justin S Williams, Joshua P Der, Claude W dePamphilis, Teh-Hui Kao
    [Show abstract] [Hide abstract]
    ABSTRACT: Petunia possesses self-incompatibility, by which pistils reject self-pollen but accept non-self-pollen for fertilization. Self-/non-self-recognition between pollen and pistil is regulated by the pistil-specific S-RNase gene and by multiple pollen-specific S-locus F-box (SLF) genes. To date, 10 SLF genes have been identified by various methods, and seven have been shown to be involved in pollen specificity. For a given S-haplotype, each SLF interacts with a subset of its non-self S-RNases, and an as yet unknown number of SLFs are thought to collectively mediate ubiquitination and degradation of all non-self S-RNases to allow cross-compatible pollination. To identify a complete suite of SLF genes of P. inflata, we used a de novo RNA-seq approach to analyze the pollen transcriptomes of S2-haplotype and S3-haplotype, as well as the leaf transcriptome of the S3S3 genotype. We searched for genes that fit several criteria established from the properties of the known SLF genes and identified the same seven new SLF genes in S2-haplotype and S3-haplotype, suggesting that a total of 17 SLF genes constitute pollen specificity in each S-haplotype. This finding lays the foundation for understanding how multiple SLF genes evolved and the biochemical basis for differential interactions between SLF proteins and S-RNases.
    The Plant cell. 07/2014;
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Pectins are acidic sugar-containing polysaccharides that are universally conserved components of the primary cell walls of plants and modulate both tip and diffuse cell growth. However, many of their specific functions and the evolution of the genes responsible for producing and modifying them are incompletely understood. The moss Physcomitrella patens is emerging as a powerful model system for the study of plant cell walls. To identify deeply conserved pectin-related genes in Physcomitrella, we generated phylogenetic trees for 16 pectin-related gene families using sequences from ten plant genomes and analyzed the evolutionary relationships within these families. Contrary to our initial hypothesis that a single ancestral gene was present for each pectin-related gene family in the common ancestor of land plants, five of the 16 gene families, including homogalacturonan galacturonosyltransferases, polygalacturonases, pectin methylesterases, homogalacturonan methyltransferases, and pectate lyase-like proteins, show evidence of multiple members in the early land plant that gave rise to the mosses and vascular plants. Seven of the gene families, the UDP-rhamnose synthases, UDP-glucuronic acid epimerases, homogalacturonan galacturonosyltransferase-like proteins, beta-1,4-galactan beta-1,4-galactosyltransferases, rhamnogalacturonan-II xylosyltransferases, and pectin acetylesterases appear to have had a single member in the common ancestor of land plants. We detected no Physcomitrella members in the xylogalacturonan xylosyltransferase, rhamnogalacturonan-I arabinosyltransferase, pectin methylesterase inhibitor, or polygalacturonase inhibitor protein families. Several gene families related to the production and modification of pectins in plants appear to have multiple members that are conserved as far back as the common ancestor of mosses and vascular plants. The presence of multiple members of these families even before the divergence of other important cell wall-related genes, such as cellulose synthases, suggests a more complex role than previously suspected for pectins in the evolution of land plants. The presence of relatively small pectin-related gene families in Physcomitrella as compared to Arabidopsis makes it an attractive target for analysis of the role of pectins in cell walls. In contrast, the absence of genes in Physcomitrella for some families suggests that certain pectin modifications, such as homogalacturonan xylosylation, arose later during land plant evolution.
    BMC Plant Biology 03/2014; 14(1):79. · 4.35 Impact Factor
  • Source
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We report the complete mitochondrial genome sequence of the flowering plant Amborella trichopoda. This enormous, 3.9-megabase genome contains six genome equivalents of foreign mitochondrial DNA, acquired from green algae, mosses, and other angiosperms. Many of these horizontal transfers were large, including acquisition of entire mitochondrial genomes from three green algae and one moss. We propose a fusion-compatibility model to explain these findings, with Amborella capturing whole mitochondria from diverse eukaryotes, followed by mitochondrial fusion (limited mechanistically to green plant mitochondria) and then genome recombination. Amborella's epiphyte load, propensity to produce suckers from wounds, and low rate of mitochondrial DNA loss probably all contribute to the high level of foreign DNA in its mitochondrial genome.
    Science 12/2013; 342(6165):1468-73. · 31.20 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Genome sequencing with next-generation sequence (NGS) technologies can now be applied to organisms pivotal to addressing fundamental biological questions, but with genomes previously considered intractable or too expensive to undertake. However, for species with large and complex genomes, extensive genetic and physical map resources have, until now, been required to direct the sequencing effort and sequence assembly. As these resources are unavailable for most species, assembling high-quality genome sequences from NGS data remains challenging. We describe a strategy that uses NGS, fluorescence in situ hybridization, and whole-genome mapping to assemble a high-quality genome sequence for Amborella trichopoda, a nonmodel species crucial to understanding flowering plant evolution. These methods are applicable to many other organisms with limited genomic resources.
    Science 12/2013; 342(6165):1516-7. · 31.20 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Carnivorous Lentibulariaceae exhibit the most sophisticated implementation of the carnivorous syndrome in plants. Their unusual lifestyle coincides with distinct genomic peculiarities such as the smallest angiosperm nuclear genomes and extremely high nucleotide substitution rates across all genomic compartments. Here, we report the complete plastid genomes from each of the three genera Pinguicula, Utricularia and Genlisea, and investigate plastome-wide changes in their molecular evolution as the carnivorous syndrome unfolds. We observe a size reduction by up to nine percent mostly due to the independent loss of genes for the plastid NAD(P)H dehydrogenase and altered proportions of plastid repeat DNA, as well as a significant plastome-wide increase of substitution rates and microstructural changes. Protein-coding genes across all gene classes show a disproportional elevation of non-synonymous substitutions, particularly in Utricularia and Genlisea. Significant relaxation of purifying selection relative to non-carnivores occurs in the plastid-encoded fraction of the photosynthesis ATP Synthase complex, the photosystem I, and in several other photosynthesis and metabolic genes. Shifts in selective regimes also affect housekeeping genes including the plastid-encoded polymerase, for which evidence for relaxed purifying selection was found once during the transition to carnivory, and a second time during the diversification of the family. Lentibulariaceae exhibit significantly enhanced rates of nucleotide substitution in most of the 130 non-coding regions. Various factors may underlie the observed patterns of relaxation of purifying selection and substitution rate increases, such as reduced net photosynthesis rates, alternative paths of nutrient uptake (including organic carbon), and impaired DNA repair mechanisms.
    Molecular Biology and Evolution 12/2013; · 10.35 Impact Factor
  • CHANCE 08/2013; 19(3):27-38.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: BACKGROUND: Sacred lotus is a basal eudicot with agricultural, medicinal, cultural and religious importance. It was domesticated in Asia about 7,000 years ago, and cultivated for its rhizomes and seeds as a food crop. It is particularly noted for its 1,300-year seed longevity and exceptional water repellency, known as the lotus effect. The latter property is due to the nanoscopic closely-packed protuberances on its self-cleaning leaf surface, which have been adapted for the manufacture of a self-cleaning industrial paint, Lotusan. RESULTS: The genome of the China Antique variety of the sacred lotus was sequenced with Illumina and 454 technologies, at respective depths of 101x and 5.2x. The final assembly has a contig N50 of 38.8 kbp and a scaffold N50 of 3.4 Mbp, and covers 86.5% of the estimated 929 Mbp total genome size. The genome notably lacks the paleo-triplication observed in other eudicots, but reveals a lineage-specific duplication. The genome has evidence of slow evolution, with a 30% slower nucleotide mutation rate than observed in grape. Comparisons of the available sequenced genomes suggest a minimum gene set for vascular plants of 4,223 genes. Strikingly, the sacred lotus has sixteen COG2132 multi-copper oxidase family proteins with root specific expression; these are involved in root meristem phosphate starvation, reflecting adaptation to limited nutrient availability in an aquatic environment. CONCLUSIONS: The slow nucleotide substitution rate makes the sacred lotus a better resource than the current standard, grape, for reconstructing the pan-eudicot genome, and should therefore accelerate comparative analysis between eudicots and monocots.
    Genome biology 05/2013; 14(5):R41. · 10.30 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: BACKGROUND: Parasitic plants, represented by several thousand species of angiosperms, use modified structures known as haustoria to tap into photosynthetic host plants and extract nutrients and water. As a result of their direct plant-plant connections with their host plant, parasitic plants have special opportunities for horizontal gene transfer, the nonsexual transmission of genetic material across species boundaries. There is increasing evidence that parasitic plants have served as recipients and donors of horizontal gene transfer (HGT), but the long-term impacts of eukaryotic HGT in parasitic plants are largely unknown. RESULTS: Here we show that a gene encoding albumin 1 KNOTTIN-like protein, closely related to the albumin 1 genes only known from papilionoid legumes, where they serve dual roles as food storage and insect toxin, was found in Phelipanche aegyptiaca and related parasitic species of family Orobanchaceae, and was likely acquired by a Phelipanche ancestor via HGT from a legume host based on phylogenetic analyses. The KNOTTINs are well known for their unique "disulfide through disulfide knot" structure and have been extensively studied in various contexts, including drug design. Genomic sequences from nine related parasite species were obtained, and 3D protein structure simulation tests and evolutionary constraint analyses were performed. The parasite gene we identified here retains the intron structure, six highly conserved cysteine residues necessary to form a KNOTTIN protein, and displays levels of purifying selection like those seen in legumes. The albumin 1 xenogene has evolved through >150 speciation events over ca. 16 million years, forming a small family of differentially expressed genes that may confer novel functions in the parasites. Moreover, further data show that a distantly related parasitic plant, Cuscuta, obtained two copies of albumin 1 KNOTTIN-like genes from legumes through a separate HGT event, suggesting that legume KNOTTIN structures have been repeatedly co-opted by parasitic plants. CONCLUSIONS: The HGT-derived albumins in Phelipanche represent a novel example of how plants can acquire genes from other plants via HGT that then go on to duplicate, evolve, and retain the specialized features required to perform a unique host-derived function.
    BMC Evolutionary Biology 02/2013; 13(1):48. · 3.29 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: BACKGROUND: Previous studies in basal angiosperms have provided insight into the diversity within the angiosperm lineage and helped to polarize analyses of flowering plant evolution. However, there is still not an experimental system for genetic studies among basal angiosperms to facilitate comparative studies and functional investigation. It would be desirable to identify a basal angiosperm experimental system that possesses many of the features found in existing plant model systems (e.g., Arabidopsis and Oryza). RESULTS: We have considered all basal angiosperm families for general characteristics important for experimental systems, including availability to the scientific community, growth habit, and membership in a large basal angiosperm group that displays a wide spectrum of phenotypic diversity. Most basal angiosperms are woody or aquatic, thus are not well-suited for large scale cultivation, and were excluded. We further investigated members of Aristolochiaceae for ease of culture, life cycle, genome size, and chromosome number. We demonstrated self-compatibility for Aristolochia elegans and A. fimbriata, and transformation with a GFP reporter construct for Saruma henryi and A. fimbriata. Furthermore, A. fimbriata was easily cultivated with a life cycle of just three months, could be regenerated in a tissue culture system, and had one of the smallest genomes among basal angiosperms. An extensive multi-tissue EST dataset was produced for A. fimbriata that includes over 3.8 million 454 sequence reads. CONCLUSIONS: Aristolochia fimbriata has numerous features that facilitate genetic studies and is suggested as a potential model system for use with a wide variety of technologies. Emerging genetic and genomic tools for A. fimbriata and closely related species can aid the investigation of floral biology, developmental genetics, biochemical pathways important in plant-insect interactions as well as human health, and various other features present in early angiosperms.
    BMC Plant Biology 01/2013; 13(1):13. · 4.35 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: BACKGROUND: Orobanchaceae is the only plant family with members representing the full range of parasitic lifestyles plus a free-living lineage sister to all parasitic lineages, Lindenbergia. A generalist member of this family, and an important parasitic plant model, Triphysaria versicolor regularly feeds upon a wide range of host plants. Here, we compare de novo assembled transcriptomes generated from laser micro-dissected tissues at the host-parasite interface to uncover details of the largely uncharacterized interaction between parasitic plants and their hosts. RESULTS: The interaction of Triphysaria with the distantly related hosts Zea mays and Medicago truncatula reveals dramatic host-specific gene expression patterns. Relative to above ground tissues, gene families are disproportionally represented at the interface including enrichment for transcription factors and genes of unknown function. Quantitative Real-Time PCR of a T. versicolor beta-expansin shows strong differential (120x) upregulation in response to the monocot host Z. mays; a result that is concordant with our read count estimates. Pathogenesis-related proteins, other cell wall modifying enzymes, and orthologs of genes with unknown function (annotated as such in sequenced plant genomes) are among the parasite genes highly expressed by T. versicolor at the parasite-host interface. CONCLUSIONS: Laser capture microdissection makes it possible to sample the small region of cells at the epicenter of parasite host interactions. The results of our analysis suggest that T. versicolor's generalist strategy involves a reliance on overlapping but distinct gene sets, depending upon the host plant it is parasitizing. The massive upregulation of a T. versicolor beta-expansin is suggestive of a mechanism for parasite success on grass hosts. In this preliminary study of the interface transcriptomes, we have shown that T. versicolor, and the Orobanchaceae in general, provide excellent opportunities for the characterization of plant genes with unknown functions.
    BMC Plant Biology 01/2013; 13(1):9. · 4.35 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Extreme haustorial parasites have long captured the interest of naturalists and scientists with their greatly reduced and highly specialized morphology. Along with the reduction or loss of photosynthesis, the plastid genome often decays as photosynthetic genes are released from selective constraint. This makes it challenging to use traditional plastid genes for parasitic plant phylogenetics, and has driven the search for alternative phylogenetic and molecular evolutionary markers. Thus, evolutionary studies, such as molecular clock-based age estimates, are not yet available for all parasitic lineages. In the present study, we extracted 14 nuclear single copy genes (nSCG) from Illumina transcriptome data from one of the "strangest plants in the world", Hydnora visseri (Hydnoraceae). A ∼15,000 character molecular dataset, based on all three genomic compartments, shows the utility of nSCG for reconstructing phylogenetic relationships in parasitic lineages. A relaxed molecular clock approach with the same multi-locus dataset, revealed an ancient age of ∼91 MYA for Hydnoraceae. We then estimated the stem ages of all independently originated parasitic angiosperm lineages using a published dataset, which also revealed a Cretaceous origin for Balanophoraceae, Cynomoriaceae and Apodanthaceae. With the exception of Santalales, older parasite lineages tend to be more specialized with respect to trophic level and have lower species diversity. We thus propose the "temporal specialization hypothesis" (TSH) implementing multiple independent specialization processes over time during parasitic angiosperm evolution.
    PLoS ONE 01/2013; 8(11):e79204. · 3.73 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Striga is a root parasitic weed that attacks many of the staple crops in Africa, India and Southeast Asia, inflicting tremendous losses in yield and for which there are few effective control measures. Studies of parasitic plant virulence and host resistance will be greatly facilitated by the recent emergence of genomic resources that include extensive transcriptome sequence datasets spanning all life stages of S. hermonthica. Functional characterization of Striga genes will require detailed analyses of gene expression patterns. Quantitative real-time PCR is a powerful tool for quantifying gene expression, but correct normalization of expression levels requires identification of control genes that have stable expression across tissues and life stages. Since no S. hermonthica housekeeping genes have been established for this purpose, we evaluated the suitability of six candidate housekeeping genes across key life stages of S. hermonthica from seed conditioning to flower initiation using qRT-PCR and high-throughput cDNA sequencing. Based on gene expression analysis by qRT-PCR and RNA-Seq across heterogeneous Striga life stages, we determined that using the combination of three genes, UBQ1, PP2A and TUB1 provides the best normalization for gene expression throughout the parasitic life cycle. The housekeeping genes characterized here provide robust standards that will facilitate powerful descriptions of parasite gene expression patterns.
    Molecular Biology Reports 12/2012; · 2.51 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: • Premise of the study: The stability of the bimodal karyotype found in Agave and closely related species has long interested botanists. The origin of the bimodal karyotype has been attributed to allopolyploidy, but this hypothesis has not been tested. Next-generation transcriptome sequence data were used to test whether a paleopolyploid event occurred on the same branch of the Agavoideae phylogenetic tree as the origin of the Yucca-Agave bimodal karyotype. • Methods: Illumina RNA-seq data were generated for phylogenetically strategic species in Agavoideae. Paleopolyploidy was inferred in analyses of frequency plots for synonymous substitutions per synonymous site (K(s)) between Hosta, Agave, and Chlorophytum paralogous and orthologous gene pairs. Phylogenies of gene families including paralogous genes for these species and outgroup species were estimated to place inferred paleopolyploid events on a species tree. • Key results: K(s) frequency plots suggested paleopolyploid events in the history of the genera Agave, Hosta, and Chlorophytum. Phylogenetic analyses of gene families estimated from transcriptome data revealed two polyploid events: one predating the last common ancestor of Agave and Hosta and one within the lineage leading to Chlorophytum. • Conclusions: We found that polyploidy and the origin of the Yucca-Agave bimodal karyotype co-occur on the same lineage consistent with the hypothesis that the bimodal karyotype is a consequence of allopolyploidy. We discuss this and alternative mechanisms for the formation of the Yucca-Agave bimodal karyotype. More generally, we illustrate how the use of next-generation sequencing technology is a cost-efficient means for assessing genome evolution in nonmodel species.
    American Journal of Botany 02/2012; 99(2):397-406. · 2.59 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Although it is agreed that a major polyploidy event, gamma, occurred within the eudicots, the phylogenetic placement of the event remains unclear. To determine when this polyploidization occurred relative to speciation events in angiosperm history, we employed a phylogenomic approach to investigate the timing of gene set duplications located on syntenic gamma blocks. We populated 769 putative gene families with large sets of homologs obtained from public transcriptomes of basal angiosperms, magnoliids, asterids, and more than 91.8 gigabases of new next-generation transcriptome sequences of non-grass monocots and basal eudicots. The overwhelming majority (95%) of well-resolved gamma duplications was placed before the separation of rosids and asterids and after the split of monocots and eudicots, providing strong evidence that the gamma polyploidy event occurred early in eudicot evolution. Further, the majority of gene duplications was placed after the divergence of the Ranunculales and core eudicots, indicating that the gamma appears to be restricted to core eudicots. Molecular dating estimates indicate that the duplication events were intensely concentrated around 117 million years ago. The rapid radiation of core eudicot lineages that gave rise to nearly 75% of angiosperm species appears to have occurred coincidentally or shortly following the gamma triplication event. Reconciliation of gene trees with a species phylogeny can elucidate the timing of major events in genome evolution, even when genome sequences are only available for a subset of species represented in the gene trees. Comprehensive transcriptome datasets are valuable complements to genome sequences for high-resolution phylogenomic analysis.
    Genome biology 01/2012; 13(1):R3. · 10.30 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Next-generation sequencing plays a central role in the characterization and quantification of transcriptomes. Although numerous metrics are purported to quantify the quality of RNA, there have been no large-scale empirical evaluations of the major determinants of sequencing success. We used a combination of existing and newly developed methods to isolate total RNA from 1115 samples from 695 plant species in 324 families, which represents >900 million years of phylogenetic diversity from green algae through flowering plants, including many plants of economic importance. We then sequenced 629 of these samples on Illumina GAIIx and HiSeq platforms and performed a large comparative analysis to identify predictors of RNA quality and the diversity of putative genes (scaffolds) expressed within samples. Tissue types (e.g., leaf vs. flower) varied in RNA quality, sequencing depth and the number of scaffolds. Tissue age also influenced RNA quality but not the number of scaffolds ≥1000 bp. Overall, 36% of the variation in the number of scaffolds was explained by metrics of RNA integrity (RIN score), RNA purity (OD 260/230), sequencing platform (GAIIx vs HiSeq) and the amount of total RNA used for sequencing. However, our results show that the most commonly used measures of RNA quality (e.g., RIN) are weak predictors of the number of scaffolds because Illumina sequencing is robust to variation in RNA quality. These results provide novel insight into the methods that are most important in isolating high quality RNA for sequencing and assembling plant transcriptomes. The methods and recommendations provided here could increase the efficiency and decrease the cost of RNA sequencing for individual labs and genome centers.
    PLoS ONE 01/2012; 7(11):e50226. · 3.73 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The rapidly increasing number of available plant genomes opens up almost unlimited prospects for biology in general and molecular phylogenetics in particular. A recent study took advantage of this data and identified a set of nuclear genes that occur in single copy in multiple sequenced angiosperms. The present study is the first to apply genomic sequence of one of these low copy genes, agt1, as a phylogenetic marker for species-level phylogenetics. Its utility is compared to the performance of several coding and non-coding chloroplast loci that have been suggested as most applicable for this taxonomic level. As a model group, we chose Tildenia, a subgenus of Peperomia (Piperaceae), one of the largest plant genera. Relationships are particularly difficult to resolve within these species rich groups due to low levels of polymorphisms and fast or recent radiation. Therefore, Tildenia is a perfect test case for applying new phylogenetic tools. We show that the nuclear marker agt1, and in particular the agt1 introns, provide a significantly increased phylogenetic signal compared to chloroplast markers commonly used for low level phylogenetics. 25% of aligned characters from agt1 intron sequence are parsimony informative. In comparison, the introns and spacer of several common chloroplast markers (trnK intron, trnK-psbA spacer, ndhF-rpl32 spacer, rpl32-trnL spacer, psbA-trnH spacer) provide less than 10% parsimony informative characters. The agt1 dataset provides a deeper resolution than the chloroplast markers in Tildenia. Single (or very low) copy nuclear genes are of immense value in plant phylogenetics. Compared to other nuclear genes that are members of gene families of all sizes, lab effort, such as cloning, can be kept to a minimum. They also provide regions with different phylogenetic content deriving from coding and non-coding parts of different length. Thus, they can be applied to a wide range of taxonomic levels from family down to population level. As more plant genomes are sequenced, we will obtain increasingly precise information about which genes return to single copy most rapidly following gene duplication and may be most useful across a wide range of plant groups.
    BMC Evolutionary Biology 12/2011; 11:357. · 3.29 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Parasitism in flowering plants has evolved at least 11 times [1]. Only one family, Orobanchaceae, comprises all major nutritional types of parasites: facultative, hemiparasitic (partially photosynthetic), and holoparasitic (nonphotosynthetic) [2]. Additionally, the family includes Lindenbergia, a nonparasitic genus sister to all parasitic Orobanchaceae [3-6]. Parasitic Orobanchaceae include species with severe economic impacts: Striga (witchweed), for example, affects over 50 million hectares of crops in sub-Saharan Africa, causing more than $3 billion in damage annually [7]. Although gene losses and increased substitution rates have been characterized for parasitic plant plastid genomes [5, 8-11], the nuclear genome and transcriptome remain largely unexplored. The Parasitic Plant Genome Project (PPGP; [2] is leveraging the natural variation in Orobanchaceae to explore the evolution and genomic consequences of parasitism in plants through a massive transcriptome and gene discovery project involving Triphysaria versicolor (facultative hemiparasite), Striga hermonthica (obligate hemiparasite), and Phelipanche aegyptiaca (Orobanche [12]; holoparasite). Here we present the first set of large-scale genomic resources for parasitic plant comparative biology. Transcriptomes of above-ground tissues reveal that, in addition to the predictable loss of photosynthesis-related gene expression in P. aegyptiaca, the nonphotosynthetic parasite retains an intact, expressed, and selectively constrained chlorophyll synthesis pathway.
    Current biology: CB 12/2011; 21(24):2098-104. · 10.99 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The rhizosphere is teemed with organisms that coordinate their symbioses using chemical signals traversing between the host root and symbionts. Chemical signals also mediate interactions between roots of different plants, perhaps the most obvious being those between parasitic Orobanchaceae and their plant hosts. Parasitic plants use specific molecules provided by host roots to initiate the development of haustoria, invasive structures critical for plant parasitism. We took a transcriptomics approach to identify parasitic plant genes associated with host factor recognition and haustorium signaling and previously identified a gene, TvPirin, which is transcriptionally up-regulated in roots of the parasitic plant Triphysaria versicolor after being exposed to the haustorium-inducing molecule 2,6-dimethoxybenzoquinone (DMBQ). Because TvPirin shares homology with proteins associated with environmental signaling in some plants, we hypothesized that TvPirin may function in host factor recognition in parasitic plants. We tested the function of TvPirin in T. versicolor roots using hairpin-mediated RNA interference. Reducing TvPirin transcripts in T. versicolor roots resulted in significantly less haustoria development in response to DMBQ exposure. We determined the transcript levels of other root expressed transcripts and found that several had reduced basal levels of gene expression but were similarly regulated by quinone exposure. Phylogenic investigations showed that TvPirin homologs are present in most flowering plants, and we found no evidence of parasite-specific gene duplication or expansion. We propose that TvPirin is a generalized transcription factor associated with the expression of a number of genes, some of which are involved in haustorium development.
    Plant physiology 11/2011; 158(2):1046-53. · 6.56 Impact Factor

Publication Stats

7k Citations
842.44 Total Impact Points


  • 2000–2014
    • Pennsylvania State University
      • Department of Biology
      University Park, Maryland, United States
    • Frostburg State University
      • Biology
      Frostburg, MD, United States
  • 2005–2013
    • William Penn University
      • Biology
      University Park, Florida, United States
    • Natural History Museum, Norway
      Kristiania (historical), Oslo County, Norway
    • Tufts University
      • Department of Biomedical Sciences
      Medford, MA, United States
  • 2007–2012
    • University of Georgia
      • Department of Plant Biology
      Athens, GA, United States
    • Western Michigan University
      • Department of Biological Sciences
      Kalamazoo, MI, United States
  • 2011
    • University of Arkansas at Monticello
      • School of Forest Resources
      Arkansas, United States
    • Mississippi State University
      • Department of Forestry
      Starkville, MS, United States
    • The University of Arizona
      • School of Plant Sciences
      Tucson, AZ, United States
  • 2010
    • Virginia Polytechnic Institute and State University
      • Department of Plant Pathology, Physiology, and Weed Science
      Blacksburg, VA, United States
  • 2007–2010
    • University of Florida
      • • Florida Museum of Natural History
      • • Department of Botany
      Gainesville, FL, United States
  • 2004–2009
    • Northeast Institute of Geography and Agroecology
      • Institute of Botany
      Beijing, Beijing Shi, China
    • University of New Mexico
      • Department of Computer Science
      Albuquerque, NM, United States
  • 2004–2005
    • Northwestern University
      • Department of Statistics
      Evanston, IL, United States
  • 1990–2005
    • Indiana University Bloomington
      • Department of Biology
      Bloomington, IN, United States
  • 2002
    • Colgate University
      • Department of Biology
      Hamilton, NY, United States
  • 2001
    • Trinity University
      • Department of Biology
      San Antonio, TX, United States
  • 1996–1998
    • Vanderbilt University
      Nashville, Michigan, United States
  • 1997
    • Southern Illinois University Carbondale
      • Department of Plant Biology
      Carbondale, IL, United States