Patrick J. Calie

Many Parallel Losses of infA from Chloroplast DNA during Angiosperm Evolution with Multiple Independent Transfers to the Nucleus

We used DNA sequencing and gel blot surveys to assess the integrity of the chloroplast gene infA, which codes for translation initiation factor 1, in >300 diverse angiosperms. Whereas most angiosperms appear to contain an intact chloroplast infA gene, the gene has repeatedly become defunct in ∼24 separate lineages of angiosperms, including almost all rosid species. In four species in which chloroplast infA is defunct, transferred and expressed copies of the gene were found in the nucleus, complete with putative chloroplast transit peptide sequences. The transit peptide sequences of the nuclear infA genes from soybean and Arabidopsis were shown to be functional by their ability to target green fluorescent protein to chloroplasts in vivo. Phylogenetic analysis of infA sequences and assessment of transit peptide homology indicate that the four nuclear infA genes are probably derived from four independent gene transfers from chloroplast to nuclear DNA during angiosperm evolution. Considering this and the many separate losses of infA from chloroplast DNA, the gene has probably been transferred many more times, making infA by far the most mobile chloroplast gene known in plants.

Plant-symbiotic fungi as chemical engineers: multi-genome analysis of the clavicipitaceae reveals dynamics of alkaloid loci

The fungal family Clavicipitaceae includes plant symbionts and parasites that produce several psychoactive and bioprotective alkaloids. The family includes grass symbionts in the epichloae clade (Epichloë and Neotyphodium species), which are extraordinarily diverse both in their host interactions and in their alkaloid profiles. Epichloae produce alkaloids of four distinct classes, all of which deter insects, and some—including the infamous ergot alkaloids—have potent effects on mammals. The exceptional chemotypic diversity of the epichloae may relate to their broad range of host interactions, whereby some are pathogenic and contagious, others are mutualistic and vertically transmitted (seed-borne), and still others vary in pathogenic or mutualistic behavior. We profiled the alkaloids and sequenced the genomes of 10 epichloae, three ergot fungi (Claviceps species), a morning-glory symbiont (Periglandula ipomoeae), and a bamboo pathogen (Aciculosporium take), and compared the gene clusters for four classes of alkaloids. Results indicated a strong tendency for alkaloid loci to have conserved cores that specify the skeleton structures and peripheral genes that determine chemical variations that are known to affect their pharmacological specificities. Generally, gene locations in cluster peripheries positioned them near to transposon-derived, AT-rich repeat blocks, which were probably involved in gene losses, duplications, and neofunctionalizations. The alkaloid loci in the epichloae had unusual structures riddled with large, complex, and dynamic repeat blocks. This feature was not reflective of overall differences in repeat contents in the genomes, nor was it characteristic of most other specialized metabolism loci. The organization and dynamics of alkaloid loci and abundant repeat blocks in the epichloae suggested that these fungi are under selection for alkaloid diversification. We suggest that such selection is related to the variable life histories of the epichloae, their protective roles as symbionts, and their associations with the highly speciose and ecologically diverse cool-season grasses.

The epichloae: alkaloid diversity and roles in symbiosis with grasses

Epichloae (Epichloë and Neotyphodium species; Clavicipitaceae) are fungi that live in systemic symbioses with cool-season grasses, and many produce alkaloids that are deterrent or toxic to herbivores. The epichloae colonize much of the aerial plant tissues, and most benignly colonize host seeds to transmit vertically. Of their four chemical classes of alkaloids, the ergot alkaloids and indole-diterpenes are active against mammals and insects, whereas peramine and lolines specifically affect insects. Comparative genomic analysis of Clavicipitaceae reveals a distinctive feature of the epichloae, namely, large repeat blocks in their alkaloid biosynthesis gene loci. Such repeat blocks can facilitate gene losses, mutations, and duplications, thus enhancing diversity of alkaloid structures within each class. We suggest that alkaloid diversification is selected especially in the vertically transmissible epichloae.

Phylogeny and Biogeography of the Carnivorous Plant Family Sarraceniaceae

The carnivorous plant family Sarraceniaceae comprises three genera of wetland-inhabiting pitcher plants: Darlingtonia in the northwestern United States, Sarracenia in eastern North America, and Heliamphora in northern South America. Hypotheses concerning the biogeographic history leading to this unusual disjunct distribution are controversial, in part because genus- and species-level phylogenies have not been clearly resolved. Here, we present a robust, species-rich phylogeny of Sarraceniaceae based on seven mitochondrial, nuclear, and plastid loci, which we use to illuminate this familys phylogenetic and biogeographic history. The family and genera are monophyletic: Darlingtonia is sister to a clade consisting of Heliamphora+Sarracenia. Within Sarracenia, two clades were strongly supported: one consisting of S. purpurea, its subspecies, and S. rosea; the other consisting of nine species endemic to the southeastern United States. Divergence time estimates revealed that stem group Sarraceniaceae likely originated in South America 44–53 million years ago (Mya) (highest posterior density [HPD] estimate = 47 Mya). By 25–44 (HPD = 35) Mya, crown-group Sarraceniaceae appears to have been widespread across North and South America, and Darlingtonia (western North America) had diverged from Heliamphora+Sarracenia (eastern North America+South America). This disjunction and apparent range contraction is consistent with late Eocene cooling and aridification, which may have severed the continuity of Sarraceniaceae across much of North America. Sarracenia and Heliamphora subsequently diverged in the late Oligocene, 14–32 (HPD = 23) Mya, perhaps when direct overland continuity between North and South America became reduced. Initial diversification of South American Heliamphora began at least 8 Mya, but diversification of Sarracenia was more recent (2–7, HPD = 4 Mya); the bulk of southeastern United States Sarracenia originated co-incident with Pleistocene glaciation, <3 Mya. Overall, these results suggest climatic change at different temporal and spatial scales in part shaped the distribution and diversity of this carnivorous plant clade.

Structure and evolution of the largest chloroplast gene (ORF2280): internal plasticity and multiple gene loss during angiosperm evolution

We have determined the nucleotide sequence of the Pelargonium x hortorum ORF2280 homolog, the largest gene in the plastid genome of most land plants, and compared it to published homologs from Nicotiana tabacum, Epifagus virginiana, Spinacia oleracea, and Marchantia polymorpha. Multiple alignment of protein sequences requires an extraordinary number of gaps, indicating a very high frequency of insertion/deletion events during the evolution of the protein; however, the overall predicted size of the protein varies relatively little among the five species. At 2 109 codons, the Pelargonium gene is smaller than other land plant ORF2280 homologs and exhibits a rate of nucleotide substitution several times higher relative to Nicotiana, Epifagus, and Spinacia. Southern-blot and restriction-mapping studies were carried out to uncover length variation in ORF2280 homologs from 279 species (representing 111 families) of angiosperms. In many independent angiosperm lineages, this gene has sustained deletions ranging in size from 200 bp to almost 6 kb. Based on the severity of deletions, we postulate that the chloroplast homolog of ORF2280 has become nonfunctional in at least four independent lineages of angiosperms.

Is subtribe Solidagininae (Asteraceae) monophyletic

As currently delimited, Solidagininae are a large (approximately 190 species) subtribe of tribe Astereae. Recent molecular and morphological studies have prompted a new definition of the subtribe, but the lack of absolutemorphological synapomorphies raises the possibility that this assemblage may not be monophyletic. Cladistic and likelihood-based analyses were conducted on a nuclear rDNA ITS sequence dataset derived from 23 of the 24 genera included in recent Solidagininae circumscriptions. Cladistic analyses identified two clades entirely composed of proposed Solidagininae genera. The data were not able to support deeper relationships, and these two clades might or might not form one monophyletic lineage. Topology testing indicated compatibility between the taxonomic definition of Solidagininae and molecular data.

Pitcher Plants (Sarracenia) Provide a 21st-Century Perspective on Infraspecific Ranks and Interspecific Hybrids: A Modest Proposal* for Appropriate Recognition and Usage

Abstract The taxonomic use of infraspecific ranks (subspecies, variety, subvariety, form, and subform), and the formal recognition of interspecific hybrid taxa, is permitted by the International Code of Nomenclature for algae, fungi, and plants. However, considerable confusion regarding the biological and systematic merits is caused by current practice in the use of infraspecific ranks, which obscures the meaningful variability on which natural selection operates, and by the formal recognition of those interspecific hybrids that lack the potential for inter-lineage gene flow. These issues also may have pragmatic and legal consequences, especially regarding the legal delimitation and management of threatened and endangered species. A detailed comparison of three contemporary floras highlights the degree to which infraspecific and interspecific variation are treated inconsistently. An in-depth analysis of taxonomy of the North American flowering plant genus Sarracenia (Sarraceniaceae) provides an ideal case study illustrating the confusion that can arise from inconsistent and apparently arbitrary designation of infraspecific ranks and hybrid taxa. To alleviate these problems, we propose the abandonment of infraspecific ranks of “variety” and “form,” and discourage naming of sterile interspecific hybrids except for use in the horticultural or agronomic trade. Our recommendations for taxonomic practice are in accord with the objectives proposed in the Systematics Agenda 2000, Systematics Agenda 2020, and the Global Strategy for Plant Conservation.

An Evolutionary Genetic Approach to Understanding Plastid Gene Function: Lessons from Photosynthetic and Nonphotosynthetic Plants

The biogenesis of chloroplasts and other plastid types requires the coordinated expression of nearly a thousand different genes, most of which new reside in the nucleus. The 90 or so protein genes and 34 ribosomal and transfer RNA genes that remain in the chloroplast genome are compactly arranged in a small circular chromosome whose size is typically about 150 Kb (1). The prokaryotic, specifically cyano-bacterial, ancestry of chloroplast DNA (cpDNA) is reflected in many of the ways its genes are organized (often into operons), transcribed (losing eubacterial-like promoters and RNA polymerase), and translated (on eubacterial-like 70S robosomes) (1, 2). Certain aspects of chloroplast gene expression, however, appear to reflect the long period of the organelle’s existence within and adaptation to the environment of the eukaryotic cell. These include the common occurrence of introns, an extensive array of splicing and other kinds of RNA processing, the long half-lives of chloroplast mRNAs, and a great reliance on post-transcriptional processes, especially translational mechanisms, for regulating the abundance of plastid proteins (1–3).

Proceedings of the 16th Annual UT-KBRIN Bioinformatics Summit 2016: bioinformatics

I1 Proceedings of the Sixteenth Annual UTKBRIN Bioinformatics Summit 2017 Eric C Rouchka, Julia H Chariker, David A Tieri, Juw Won Park Department of Computer Engineering and Computer Science, University of Louisville, Duthie Center for Engineering, Louisville, KY 40292, USA; Kentucky Biomedical Research Infrastructure (KBRIN) Bioinformatics Core, 522 East Gray Street, Louisville, KY 40292, USA; Department of Psychological and Brain Sciences, University of Louisville, Louisville, KY 40292, USA; Department of Anatomical Sciences and Neurobiology, University of Louisville, Louisville, KY 40292, USA Correspondence: Eric C Rouchka (eric.rouchka@louisville.edu) BMC Bioinformatics 2017, 18(Suppl 9):I1

Using HPC for teaching and learning bioinformatics software: Benefits and challenges

Background We present our work on using the XSEDE high-performance computing (HPC) network to support and facilitate hands-on bioinformatics tasks for participants of our Essentials of Next Generation Sequencing (NGS) workshop, as well as for students and other learners. In the summer of 2012, the University of Kentucky hosted the NGS workshop, attended by faculty and students from across the Commonwealth who were introduced to the laboratory and bioinformatic components of next-generation sequencing and sequence analysis. Participants used next-generation technology to sequence real genetic material, then used a variety of bioinformatics software tools to assemble those sequences, compare and align them to other sequences, predict genes, and visualize the genome. Due to the success of the 2012 workshop, the second workshop, planned for this summer, is expected to be larger in scale and to include even more participants. It will furthermore include several additional bioinformatics tools and tasks. Since participants will be simultaneously running intensive bioinformatics computing tasks, the resources required will exceed the capacity of the single twelve-core server used to support the workshop last year. One particular resource that appears promising to meet our intensive computational needs is the XSEDE grid computing network, a follow-on to the TeraGrid project designed specifically for “e-Science” and scientific computing. Many of the systems in the XSEDE network already support some of the software used within our workshop; however, many of the programs we will demonstrate have not previously been installed on tested on the XSEDE network. We will describe our experiences porting these applications to, and deploying them on, XSEDE. We will also discuss the challenges that the HPC approach presents for teaching and learning, particularly the complexities of navigating between time-sharing systems and remote job scheduling.