A5032828176- Plant Diversity and Evolution
- Plant and animal studies
- Plant Reproductive Biology
- Fern and Epiphyte Biology
- Plant Molecular Biology Research
- Plant Parasitism and Resistance
- Plant and Fungal Species Descriptions
- Plant Taxonomy and Phylogenetics
- Ecology and Vegetation Dynamics Studies
- Photosynthetic Processes and Mechanisms
- Ginkgo biloba and Cashew Applications
- Seed Germination and Physiology
- Glioma Diagnosis and Treatment
- Paleontology and Stratigraphy of Fossils
- Plant tissue culture and regeneration
- Botanical Research and Applications
- Plant Water Relations and Carbon Dynamics
- Mycorrhizal Fungi and Plant Interactions
- Marine and coastal plant biology
- Flowering Plant Growth and Cultivation
- Botany and Geology in Latin America and Caribbean
- History of Science and Natural History
- Botany and Plant Ecology Studies
- Soybean genetics and cultivation
- Evolution and Science Education
Harvard University
2015-2024
U.S. National Arboretum
2016-2024
Harvard University Press
2011-2023
University of Minnesota
2023
Evolutionary Genomics (United States)
2020
In-Q-Tel
2017
University of Colorado Boulder
2001-2013
University of Colorado System
2009-2011
University of Bristol
2002
Radboud University Nijmegen
2002
Charles Darwin's "abominable mystery" has come to symbolize just about all aspects of the origin and early evolution flowering plants. Yet, there never been an analysis precisely what Darwin thought was so abominably mysterious. Here I explicate thoughts frustrations with fossil record plants as revealed in correspondence Joseph Hooker, Gaston de Saporta, Oswald Heer between 1875 1881. also examine essay by John Ball that prompted write his letter Hooker July 1879. Contrary is generally...
Plant-associated microorganisms affect the health of their hosts in diverse ways, yet distribution these organisms within individual plants remains poorly understood. To address this knowledge gap, we assessed spatial variability bacterial community diversity and composition found on aboveground tissues Ginkgo biloba trees. We sampled communities from > 100 locations per tree, including leaf, branch trunk samples used high-throughput sequencing 16S rRNA gene to determine communities....
The last decade has witnessed a resurgence in the study of evolution plant development, combining investigations systematics, developmental morphology, molecular genetics, and evolution. integration phylogenetic studies, structural analyses fossil extant taxa, genetic information allows formulation explicit testable hypotheses for morphological characters. These comprehensive approaches provide opportunities to dissect major transitions among land plants, including those associated with...
The relationship between developmental events and the cell cycle was examined in sperm of Arabidopsis thaliana. Sperm rapidly enter S (synthesis) phase after inception from mitosis generative cell. pollen grains within anthers continue to synthesize DNA, at time pollination, contain approximately 1.5C DNA. Following through during tube growth. By tubes reach ovary, nuclei 1.75C Just prior double fertilization, embryo sacs 2C quantity These data indicate that molecular programs associated...
During regeneration, differentiated plant cells can be reprogrammed to produce stem cells, a process that requires coordination of cell cycle reactivation with acquisition other cellular characteristics. However, the factors coordinate two functions during reprogramming have not been determined. Here, we report link between and new cell-type characteristics through activity cyclin-dependent kinase A (CDKA) in moss Physcomitrella patens. Excised gametophore leaf P. patens are readily...
Summary Stem tissues from different internodes of 4–6 week‐old Zinnia elegans cv. Envy plants were sectioned and stained with chromogenic substrates previously used in studies laccases ( p ‐diphenol:O 2 oxidoreductases) isolated tree tissues. The pattern color development found when stem sections the presence absence H O suggested that oxidoreductase activity was tightly correlated spatially temporally lignification secondary cell walls developing primary xylem. correlation between this...
Double fertilization and the associated formation of endosperm have long been considered unique defining characters (autapomorphies) angiosperms. During normal in Ephedra nevadensis, a nonflowering seed plant, fusion second sperm nucleus with ventral canal occurs regularly within egg cytoplasm. The occurrence double assumes added significance light its critical phylogenetic position as basal member most closely related extant group plants (Gnetales) to Thus, angiosperms may represent an...
Commentary p 572
The recent consensus that Amborellaceae, Nymphaeales, and Austrobaileyales form the three earliest-diverging lineages of angiosperms has led comparative biologists to reconsider origin early developmental evolution angiosperm seven-celled/eight-nucleate (Polygonum-type) female gametophyte. Illicium mexicanum (Illiciaceae; Austrobaileyales) develops a four-celled/four-nucleate ontogenetic sequence gametophyte is consistent with all other also Nymphaeales likely plesiomorphy angiosperms. A...
Roots of representative epiphytic orchids were examined for anatomical detail, desiccation resistance and evidence CAM activity. Those “shootless” taxa ( Campylocentrum pachyrrhizum (Reichenb. f.) Rolfe, Harrisella porrecta Reichenb. Fawc. & Rendle, Polyradicion lindenii (Lindl.) Cogn. ex Urban) a semi‐shootless type Kingidium taeniale P. F. Hunt) bear thinner or eroded velamina greater volumes cortical intercellular space than do those the leafy forms tested sellowii Encyclia tampensis...
For more than a century, the common ancestor of flowering plants was thought to have had seven-celled, eight-nucleate Polygonum-type female gametophyte. It is now evident that not one, but in fact three, patterns gametophyte development and mature structure characterize ancestors four most ancient clades extant angiosperms: Amborella-type, Nuphar/Schisandra-type Polygonum-type. The Amborella-type restricted single species, Amborella trichopoda, at maturity consists eight cells nine nuclei....
Roots of Sobralia macrantha , a largely terrestrial orchid, bear typical multilayered velamen underlaid by cortical exodermis. The latter consists densely cytoplasmic passage cells regularly interspersed among much larger, elongate, vacuolate cells. A structure which may be peculiar to or at least unusually well developed there—the fibrous body—consists numerous intermeshed and divided wall outgrowths arising from two three positioned directly over the cell. This body is designed retard root...
Many plant species are characterized by a life cycle with long‐lived, subterranean phase that is completely dependent on mycorrhizal fungal symbionts for fixed carbon. This type of both phylogenetically and ecologically widespread found in diverse vascular lineages from the tropics to subalpine meadows. Here we report molecular identities arbuscular fungi associated autotrophic underground mycoheterotrophic phases ferns Botrychium crenulatum B. lanceolatum . We show Glomus taxa also...
The evolution of female gametophyte development provides an example how minor ontogenetic modifications can impact the functional biology seeds. Mature Peperomia-type gametophytes are normally depicted as 16-nucleate, nine-celled structures. However, recent ultrastructural data have demonstrated that many previous reports were incorrect, suggesting our understanding ontogeny is incomplete. In this investigation, and early seed described in Peperomia dolabriformis, P. jamesoniana, hispidula....
For more than 225 million y, all seed plants were woody trees, shrubs, or vines. Shortly after the origin of angiosperms ∼140 y ago (MYA), Nymphaeales (water lilies) became one first lineages to deviate from their ancestral, habit by losing vascular cambium, meristematic population cells that produces secondary xylem (wood) and phloem. Many genes gene families regulate differentiation tissues also primary phloem, which are produced apical meristems retained in nearly plants. Here, we...
A phylogenetically based comparative investigation of endosperm development was undertaken in a sample 13 basal angiosperm taxa. The specific goals were to (1) provide full developmental analysis all aspects each species, (2) compare patterns among taxa determine phylogenetic character distribution, (3) reconstruct the ancestral pattern for angiosperms, and (4) explore scenarios ontogenetic evolution that occurred during early radiation flowering plants. Five taxa, Acorus calamus, Cabomba...
The formation of a polyploid endosperm tissue has long been considered unique and defining feature (autapomorphy) angiosperms. Contemporaneous with the fertilization an egg nucleus by sperm in Ephedra trifurca (a nonflowering seed plant closely related to angiosperms), second event previously shown occur between sister nucleus. Development product is now be fundamentally similar that primitive flowering plants: both are characterized initial period free nuclear proliferation followed process...
For almost a century, events relating to the evolutionary origin of endosperm, unique embryo-nourishing tissue that is essential reproductive process in flowering plants, have remained mystery. Integration recent advances phylogenetic reconstruction, comparative biology, and genetic theory can be used elucidate forces associated with establishment endosperm. Endosperm shown derived from one two embryos formed during rudimentary "double fertilization" evolved ancestors angiosperms....