Fidelity and diagnostic species concepts in vegetation classification in the Rocky Mountains, northern Utah, USA

The concepts of diagnostic species and fidelity have been used frequently in European phytosociology but rarely in North American vegetation classification. We developed a classification of the vegetation of a mountainous area of northern Utah and compared the diagnostic species approach with the indicator-species approach of habitat type classification sensu Daubenmire prevailing in the U.S. Interior West. A total of 157 forest and nonforested plots were described by vascular plants and basic environmental factors. Clustering with RandomForest classification and ordination reduced the original number of plots to 26 meaningful vegetation units. Of these 26 units, 22 were strong, having four or more faithful species. Four units were weak, having less than three faithful species. We identified species diagnostic of particular vegetation units that are potentially useful for recognition of these units in the field. We proposed vegetation types at the level of vegetation alliances and associations, and correlated them with environmental factors. We found our vegetation units to be more strongly associated with the underlying environment than major habitat types sensu Daubenmire. Our approach to classification has the potential to directly link vegetation with the physical environment and could be the basis for a substantial improvement of vegetation classification in the central Rocky Mountains

Phylogenomics and morphological evolution of the mega-diverse genus Artemisia (Asteraceae: Anthemideae): implications for its circumscription and infrageneric taxonomy

Background and Aims Artemisia is a mega-diverse genus consisting of ~400 species. Despite its medicinal importance and ecological significance, a well-resolved phylogeny for global Artemisia, a natural generic delimitation and infrageneric taxonomy remain missing, owing to the obstructions from limited taxon sampling and insufficient information on DNA markers. Its morphological characters, such as capitulum, life form and leaf, show marked variations and are widely used in its infrageneric taxonomy. However, their evolution within Artemisia is poorly understood. Here, we aimed to reconstruct a well-resolved phylogeny for global Artemisia via a phylogenomic approach, to infer the evolutionary patterns of its key morphological characters and to update its circumscription and infrageneric taxonomy. Methods We sampled 228 species (258 samples) of Artemisia and its allies from both fresh and herbarium collections, covering all the subgenera and its main geographical areas, and conducted a phylogenomic analysis based on nuclear single nucleotide polymorphisms (SNPs) obtained from genome skimming data. Based on the phylogenetic framework, we inferred the possible evolutionary patterns of six key morphological characters widely used in its previous taxonomy. Key Results The genus Kaschgaria was revealed to be nested in Artemisia with strong support. A well-resolved phylogeny of Artemisia consisting of eight highly supported clades was recovered, two of which were identified for the first time. Most of the previously recognized subgenera were not supported as monophyletic. Evolutionary inferences based on the six morphological characters showed that different states of these characters originated independently more than once. Conclusions The circumscription of Artemisia is enlarged to include the genus Kaschgaria. The morphological characters traditionally used for the infrageneric taxonomy of Artemisia do not match the new phylogenetic tree. They experienced a more complex evolutionary history than previously thought. We propose a revised infrageneric taxonomy of the newly circumscribed Artemisia, with eight recognized subgenera to accommodate the new results.This work was supported by the National Natural Science Foundation of China (grant nos. 31870179, 31570204, 31270237 and J1310002), the International Partnership Program (grant no. 151853KYSB20190027), Sino-Africa Joint Research Center (grant no. SAJC201614), Key technology projects of Jiangxi Province's major scientific and technological research and development project (grant no. 20223AAF01007), Survey of Wildlife Resources in Key Areas of Tibet (grant no. ZL202203601) and National Plant Specimen Resource Center (grant no. E0117G1001) of the Chinese Academy of Sciences, Key Project at Central Government Level: The Ability Establishment of Sustainable Use of Valuable Chinese Medicine Resources (grant no. 2060302) and Project of the Central Siberian Botanical Garden of the Siberian Branch of the Russian Academy of Sciences (grant no. AAAA-A21-121011290024-5).Abstract INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION Conclusions SUPPLEMENTARY DATA FUNDING ACKNOWLEDGEMENTS CONFLICT OF INTEREST LITERATURE CITED Supplementary dat

Acellular Bone Marrow Extracts Significantly Enhance Engraftment Levels of Human Hematopoietic Stem Cells in Mouse Xeno-Transplantation Models

Hematopoietic stem cells (HSC) derived from cord blood (CB), bone marrow (BM), or mobilized peripheral blood (PBSC) can differentiate into multiple lineages such as lymphoid, myeloid, erythroid cells and platelets. The local microenvironment is critical to the differentiation of HSCs and to the preservation of their phenotype in vivo. This microenvironment comprises a physical support supplied by the organ matrix as well as tissue specific cytokines, chemokines and growth factors. We investigated the effects of acellular bovine bone marrow extracts (BME) on HSC in vitro and in vivo. We observed a significant increase in the number of myeloid and erythroid colonies in CB mononuclear cells (MNC) or CB CD34+ cells cultured in methylcellulose media supplemented with BME. Similarly, in xeno-transplantation experiments, pretreatment with BME during ex-vivo culture of HSCs induced a significant increase in HSC engraftment in vivo. Indeed, we observed both an increase in the number of differentiated myeloid, lymphoid and erythroid cells and an acceleration of engraftment. These results were obtained using CB MNCs, BM MNCs or CD34+ cells, transplanted in immuno-compromised mice (NOD/SCID or NSG). These findings establish the basis for exploring the use of BME in the expansion of CB HSC prior to HSC Transplantation. This study stresses the importance of the mechanical structure and soluble mediators present in the surrounding niche for the proper activity and differentiation of stem cells

Humanized Rag1−/−γc−/− Mice Support Multilineage Hematopoiesis and Are Susceptible to HIV-1 Infection via Systemic and Vaginal Routes

Several new immunodeficient mouse models for human cell engraftment have recently been introduced that include the Rag2−/−γc−/−, NOD/SCID, NOD/SCIDγc−/− and NOD/SCIDβ2m−/− strains. Transplantation of these mice with CD34+ human hematopoietic stem cells leads to prolonged engraftment, multilineage hematopoiesis and the capacity to generate human immune responses against a variety of antigens. However, the various mouse strains used and different methods of engrafting human cells are beginning to illustrate strain specific variations in engraftment levels, duration and longevity of mouse life span. In these proof-of-concept studies we evaluated the Balb/c-Rag1−/−γ−/− strain for engraftment by human fetal liver derived CD34+ hematopoietic cells using the same protocol found to be effective for Balb/c-Rag2−/−γc−/− mice. We demonstrate that these mice can be efficiently engrafted and show multilineage human hematopoiesis with human cells populating different lymphoid organs. Generation of human cells continues beyond a year and production of human immunoglobulins is noted. Infection with HIV-1 leads to chronic viremia with a resultant CD4 T cell loss. To mimic the predominant sexual viral transmission, we challenged humanized Rag1−/−γc−/− mice with HIV-1 via vaginal route which also resulted in chronic viremia and helper T cell loss. Thus these mice can be further exploited for studying human pathogens that infect the human hematopoietic system in an in vivo setting

Germination and dormancy of seeds in Echinacea purpurea (L.) Moench (Asteraceae)

Seeds of Echinacea purpurea (L.) Moench display low germination rates and a wide variation in rates of emergence, hindering production considerably. A few factors, all known to affect germination of Echinacea purpurea seeds were investigated. It was found that treatments of gibberellic acid (GA3) and ethephon significantly increased germination percentage and shortened mean germination time (MGT) and prechilling treatment resulted in a large increase in percentage and rate of germination, both in darkness and in light. A prechilling treatment for 14 days at 4°C in a 200 mg/L GA3 or 1 mM ethepon solution in continuous light, followed by a germination period in light at 20/30°C (16/8h), induced over 90% seed germination. In addition, removing the seed coats or damaging the seeds also proved to be conducive to improving seed germination. The experimental results showed that dormancy of E. purpurea seeds is partly due to seed coat restriction. The dormancy mechanisms are discussed

Monograph of Artemisia Subgenus Tridentatae (Asteraceae-Anthemideae)

Artemisia subgenus Tridentatae (Asteraceae-Asteroideae-Anthemideae-Artemisiinae) comprises 13 species, including 12 subspecies, of shrubs endemic to western North America, including the coastal areas of Baja California, the grasslands of the Great Plains, the basalt scablands of the Columbia Plateau, the western shrub lands of Canada, and the warm deserts of the Colorado Plateaus. The Tridentatae lineage underwent a period of rapid diversification and expansion, especially since the last glacial period. The greatest abundance of shrubs occurs within the arid Great Basin, a cold desert that was occupied by Pleistocene lakes. Taxa apparently representing ancestral lineages (A. rigida and A. tripartita) occur outside the margins of this inland desert. In spite of the extraordinary ecological specializations among the taxa, there is relatively little genetic differentiation, and morphological differences are often subtle. Differences in soil type, temperature, and moisture regimes distinguish the habitats of species as well as subspecies. Hybridization between species is rare, although hybridization among subspecies is common where populations are sympatric or habitats have been disturbed. Morphological differences among taxa primarily include discontinuities in growth form, the shape of the crown, the structure of the inflorescence, and habit (evergreen or deciduous, root-sprouting or not). Differences in leaf anatomy are significant and physiologically correlated, helping to define species boundaries but of no utility in field identification. Pollen varies notably in shape and size, and may prove to be useful in distinguishing species in stratigraphic profiles. Floral morphology varies little (florets and cypselae are nearly identical), but sexual arrangement within floral heads (capitula) defines sections: sect. Tridentatae is homogamous (all florets are perfect and fertile), and sect. Nebulosae is heterogamous (central florets are perfect or sterile, marginal florets are pistillate). An expanded circumscription and the geographic range of subg. Tridentatae is proposed. In order to accommodate morphological differences while keeping alliances indicated by molecular studies, subg. Tridentatae is divided into two new sections: sect. Tridentatae (10 species) and sect. Nebulosae; the latter includes A. californica and A. nesiotica (formerly placed in subg. Artemisia), and A. filifolia (formerly placed in subg. Dracunculus). Morphology and anatomy, ploidy levels, phytogeography, and phylogeny are discussed. Full synonymies and descriptions are provided for all taxa, as well as a key, specimen citations, illustrations, and maps

Artemisia L.

The second edition of The Jepson Manual thoroughly updates this acclaimed work, the single most comprehensive resource on California\u27s amazingly diverse flora. The Jepson Manual, second edition, integrates the latest science with the results of intensive fieldwork, institutional collaboration, and efforts of hundreds of contributing authors into an essential reference on California\u27s native and naturalized vascular plants