Convergent molecular evolution among ash species resistant to the emerald ash borer.

Recent studies show that molecular convergence plays an unexpectedly common role in the evolution of convergent phenotypes. We exploited this phenomenon to find candidate loci underlying resistance to the emerald ash borer (EAB, Agrilus planipennis), the United States' most costly invasive forest insect to date, within the pan-genome of ash trees (the genus Fraxinus). We show that EAB-resistant taxa occur within three independent phylogenetic lineages.

Genome sequence and genetic diversity of European ash trees.

Ash trees (genus Fraxinus, family Oleaceae) are widespread throughout the Northern Hemisphere, but are being devastated in Europe by the fungus Hymenoscyphus fraxineus, causing ash dieback, and in North America by the herbivorous beetle Agrilus planipennis. Here we sequence the genome of a low-heterozygosity Fraxinus excelsior tree from Gloucestershire, UK, annotating 38,852 protein-coding genes of which 25% appear ash specific when compared with the genomes of ten other plant species. Analyses of paralogous genes suggest a whole-genome duplication shared with olive (Olea europaea, Oleaceae).

Transcriptome Profiling of the Green Alga Spirogyra pratensis (Charophyta) Suggests an Ancestral Role for Ethylene in Cell Wall Metabolism, Photosynthesis, and Abiotic Stress Responses.

It is well known that ethylene regulates a diverse set of developmental and stress-related processes in angiosperms, yet its roles in early-diverging embryophytes and algae are poorly understood. Recently, it was shown that ethylene functions as a hormone in the charophyte green alga Spirogyra pratensis Since land plants evolved from charophytes, this implies conservation of ethylene as a hormone in green plants for at least 450 million years. However, the physiological role of ethylene in charophyte algae has remained unknown.

Challenging the paradigms of leaf evolution: Class III HD-Zips in ferns and lycophytes.

Despite the extraordinary significance leaves have for life on Earth, their origin and development remain vigorously debated. More than a century of paleobotanical, morphological, and phylogenetic research has still not resolved fundamental questions about leaves. Developmental genetic data are sparse in ferns, and comparative studies of lycophytes and seed plants have reached opposing conclusions on the conservation of a leaf developmental program.

Plant Evolution: Evolving Antagonistic Gene Regulatory Networks.

Developing a structurally complex phenotype requires a complex regulatory network. A new study shows how gene duplication provides a potential source of antagonistic interactions, an important component of gene regulatory networks.

World checklist of hornworts and liverworts.

A working checklist of accepted taxa worldwide is vital in achieving the goal of developing an online flora of all known plants by 2020 as part of the Global Strategy for Plant Conservation. We here present the first-ever worldwide checklist for liverworts (Marchantiophyta) and hornworts (Anthocerotophyta) that includes 7486 species in 398 genera representing 92 families from the two phyla. The checklist has far reaching implications and applications, including providing a valuable tool for taxonomists and systematists, analyzing phytogeographic and diversity patterns, aiding in the assessment of floristic and taxonomic knowledge, and identifying geographical gaps in our understanding of the global liverwort and hornwort flora.

The Evolutionary Origin of a Terrestrial Flora.

Life on Earth as we know it would not be possible without the evolution of plants, and without the transition of plants to live on land. Land plants (also known as embryophytes) are a monophyletic lineage embedded within the green algae. Green algae as a whole are among the oldest eukaryotic lineages documented in the fossil record, and are well over a billion years old, while land plants are about 450-500 million years old.

Evaluation of BLAST-based edge-weighting metrics used for homology inference with the Markov Clustering algorithm.

Background: Clustering protein sequences according to inferred homology is a fundamental step in the analysis of many large data sets. Since the publication of the Markov Clustering (MCL) algorithm in 2002, it has been the centerpiece of several popular applications. Each of these approaches generates an undirected graph that represents sequences as nodes connected to each other by edges weighted with a BLAST-based metric.

Conservation of ethylene as a plant hormone over 450 million years of evolution.

Land plants evolved more than 450 million years ago from a lineage of freshwater charophyte green algae(1). The extent to which plant signalling systems existed before the evolutionary transition to land is unknown. Although charophytes occupy a key phylogenetic position for elucidating the origins of such signalling systems(2-4), there is a paucity of sequence data for these organisms(5,6).

Metatranscriptome profiling of a harmful algal bloom.

Metagenomic methods provide a powerful means to investigate complex ecological phenomena. Developed originally for study of Bacteria and Archaea, the application of these methods to eukaryotic microorganisms is yet to be fully realized. Most prior environmental molecular studies of eukaryotes have relied heavily on PCR amplification with eukaryote-specific primers.

Directional auxin transport mechanisms in early diverging land plants.

The emergence and radiation of multicellular land plants was driven by crucial innovations to their body plans. The directional transport of the phytohormone auxin represents a key, plant-specific mechanism for polarization and patterning in complex seed plants. Here, we show that already in the early diverging land plant lineage, as exemplified by the moss Physcomitrella patens, auxin transport by PIN transporters is operational and diversified into ER-localized and plasma membrane-localized PIN proteins.

Extant diversity of bryophytes emerged from successive post-Mesozoic diversification bursts.

Unraveling the macroevolutionary history of bryophytes, which arose soon after the origin of land plants but exhibit substantially lower species richness than the more recently derived angiosperms, has been challenged by the scarce fossil record. Here we demonstrate that overall estimates of net species diversification are approximately half those reported in ferns and ∼30% those described for angiosperms. Nevertheless, statistical rate analyses on time-calibrated large-scale phylogenies reveal that mosses and liverworts underwent bursts of diversification since the mid-Mesozoic.

Genetic analysis of DEFECTIVE KERNEL1 loop function in three-dimensional body patterning in Physcomitrella patens.

DEFECTIVE KERNEL1 (DEK1) of higher plants plays an essential role in position-dependent signaling and consists of a large transmembrane domain (MEM) linked to a protease catalytic domain and a regulatory domain. Here, we show that the postulated sensory Loop of the MEM domain plays an important role in the developmental regulation of DEK1 activity in the moss Physcomitrella patens. Compared with P.

Overly simplistic substitution models obscure green plant phylogeny.

Phylogenetic analysis is an increasingly common and valuable component of plant science. Knowledge of the phylogenetic relationships between plant groups is a prerequisite for understanding the origin and evolution of important plant features, and phylogenetic analysis of individual genes and gene families provides fundamental insights into how those genes and their functions evolved. However, despite an active research community exploring and improving phylogenetic methods, the analytical methods commonly used, and the phylogenetic results they produce, are accorded far more confidence than they warrant.

Horizontal gene transfer: accidental inheritance drives adaptation.

Few facts in biology are more certain than offspring inheriting genetic material from their parents, but not all genes are acquired this way. A new report documents the horizontal transfer of a potentially adaptive gene between distantly related plants.

A molecular phylogeny of the Lepidozia generic complex supports re-circumscription of the Lepidozioideae.

Five molecular markers (chloroplast rbcL and trnL-trnF, mitochondrial nad5-nad4, and nuclear ITS1 and ITS2) were used to investigate membership of the Lepidoziaceae, subfamily Lepidozioideae and relationships between its constituent species. The Lepidozioideae (comprising Lepidozia, Telaranea, Kurzia, Sprucella, Psiloclada) are polyphyletic as are two of its five constituent genera (Telaranea and Kurzia). We find strong support for a monophyletic lineage comprising Lepidozia, Sprucella (nested within Lepidozia), and part of Telaranea.

A multi-locus molecular phylogeny of the Lepidoziaceae: laying the foundations for a stable classification.

The Lepidoziaceae, with over 700 species in 30 genera, is one of the largest leafy liverwort families. Despite receiving considerable attention, the composition of subfamilies and genera remains unsatisfactorily resolved. In this study, 10 loci (one nuclear 26S, two mitochondrial nad1 and rps3, and seven chloroplast atpB, psbA, psbT-psbH, rbcL, rps4, trnG and trnL-trnF) are used to estimate the phylogeny of 93 species of Lepidoziaceae.

Trichocomaceae in bark survive high temperatures and fire.

Fifty-six species in the Trichocomaceae were recovered from bark of trees and shrubs from hot arid and temperate regions, and following one fire in a temperate region of Australia. Fungi were recovered from dry bark after incubation for up to 1 h at up to 105 degrees C. Fourteen species also regenerated on agar after their conidia were heated for 1 h at 105 degrees C.

Department of Defense West Nile virus surveillance in 2002.

The Department of Defense (DoD) has engaged in West Nile virus (WNV) surveillance and response since 1999. In 2002, the three Services continued their cooperative, multidisciplinary approach to the WNV outbreak. Activities included a doubling of mosquito surveillance and vector control responses, extension of and doubling of bird and nonhuman mammal surveillance to all four continental United States regions, expanded diagnostic testing by DoD laboratories, and installation environmental clean up and personnel protection campaigns.