Digital Commons Network^™

Structural Basis For Light Control Of Cell Development Revealed By Crystal Structures Of A Myxobacterial Phytochrome, Nicole C. Woitowich, Andrei S. Halavaty, Patricia Waltz, Christopher Kupitz, Joseph Valera, Gregory Tracy, Kevin D. Gallagher, Elin Claesson, Takanori Nakane, Suraj Pandey, Garrett Nelson, Rie Tanaka, Eriko Nango, Eiichi Mizohata, Shigeki Owada, Kensure Tono, Yasumasa Joti, Angela C. Nugent, Hardik Patel, Ayesha Mapara, James Hopkins, Phu Duong, Dorina Bizhga, Svetlana E. Kovaleva, Rachel St. Peter, Cynthia N. Hernandez, Wesley B. Ozarowski, Shatabdi Roy-Chowdhuri, Jay-How Yang, Petra Edlund, Heikki Takala, Janne Ihalainen, Jennifer Brayshaw, Tyler Norwood, Ishwor Poudyal, Petra Fromme, John C.H. Spence, Keith Moffat, Sebastian Westenhoff, Marius Schmidt, Emina A. Stojkovic

Biology Faculty Publications

Phytochromes are red-light photoreceptors that were first characterized in plants, with homologs in photosynthetic and non-photosynthetic bacteria known as bacteriophytochromes (BphPs). Upon absorption of light, BphPs interconvert between two states denoted Pr and Pfr with distinct absorption spectra in the red and far-red. They have recently been engineered as enzymatic photoswitches for fluorescent-marker applications in non-invasive tissue imaging of mammals. This article presents cryo- and room-temperature crystal structures of the unusual phytochrome from the non-photosynthetic myxobacterium Stigmatella aurantiaca (SaBphP1) and reveals its role in the fruitingbody formation of this photomorphogenic bacterium. SaBphP1 lacks a conserved histidine (His) in the chromophore-binding …

Mobile Elements Shape Plastome Evolution In Ferns, Tanner A. Robison, Amanda L. Grusz, Paul G. Wolf, Jeffrey P. Mower, Blake D. Fauskee, Karla Sosa, Eric Schuettpelz

Biology Faculty Publications

Plastid genomes display remarkable organizational stability over evolutionary time. From green algae to angiosperms, most plastid genomes are largely collinear, with only a few cases of inversion, gene loss, or, in extremely rare cases, gene addition. These plastome insertions are mostly clade-specific and are typically of nuclear or mitochondrial origin. Here, we expand on these findings and present the first family-level survey of plastome evolution in ferns, revealing a novel suite of dynamic mobile elements. Comparative plastome analyses of the Pteridaceae expose several mobile open reading frames that vary in sequence length, insertion site, and configuration among sampled taxa. Even …

Generalist And Specialist Mite Herbivores Induce Similar Defense Responses In Maize And Barley But Differ In Susceptibility To Benzoxazinoids, Huyen Bui, Robert Greenhalgh, Alice Ruckert, Gunbharpur S. Gill, Sarah Lee, Ricardo A. Ramirez, Richard M. Clark

Biology Faculty Publications

While substantial progress has been made in understanding defense responses of cereals to insect herbivores, comparatively little is known about responses to feeding by spider mites. Nevertheless, several spider mite species, including the generalist Tetranychus urticae and the grass specialist Oligonychus pratensis, cause damage on cereals such as maize and wheat, especially during drought stress. To understand defense responses of cereals to spider mites, we characterized the transcriptomic responses of maize and barley to herbivory by both mite species, and included a wounding control against which modulation of defenses could be tested. T. urticae and O. pratensis induced highly …

Why Large Seeds With Physical Dormancy Become Nondormant Earlier Than Small Ones, Ailton G. Rodrigues-Junior, Ana Caroline M. P. Mello, Carol C. Baskin, Jerry M. Baskin, Denise M. T. Oliveira, Queila S. Garcia

Biology Faculty Publications

Under natural conditions, large seeds with physical dormancy (PY) may become water permeable earlier than small ones. However, the mechanism for this difference has not been elucidated. Thus, our aim was to evaluate the traits associated with PY in seeds of Senna multijuga (Fabaceae) and to propose a mechanism for earlier dormancy-break in large than in small seeds. Two seedlots were collected and each separated into large and small seeds. Seed dry mass, water content, thickness of palisade layer in the hilar and distal regions and the ratio between palisade layer thickness (P) in the lens fissure and seed mass …

Fungal Endophyte Alternaria Tenuissima Can Affect Growth And Selenium Accumulation In Its Hyperaccumulator Host Astragalus Bisulcatus, Stormy D. Lindblom, Ami L. Wangeline, Jose R. Valdez Barillas, Berthal Devilbiss, Sirine C. Fakra, Elizabeth A. H. Pilon-Smits

Biology Faculty Publications

Endophytes can enhance plant stress tolerance by promoting growth and affecting elemental accumulation, which may be useful in phytoremediation. In earlier studies, up to 35% elemental selenium (Se⁰ ) was found in Se hyperaccumulator Astragalus bisulcatus. Since Se⁰ can be produced by microbes, the plant Se⁰ was hypothesized to be microbe-derived. Here we characterize a fungal endophyte of A. bisulcatus named A2. It is common in seeds from natural seleniferous habitat containing 1,000– 10,000 mg kg^-1 Se. We identified A2 as Alternaria tenuissima via 18S rRNA sequence analysis and morphological characterization. X-ray microprobe analysis of A. …

Demographic Hallmarks Of An Overbrowsed Population State In American Ginseng, James B. Mcgraw, Jennifer L. Chandler

Biology Faculty Publications

Effects of high deer herbivory in North America on populations of favored plant browse species have been well-documented, however since less palatable plants now dominate the understory, we asked whether these species could be vulnerable as well, and if so, what symptoms might signal that this was occurring? Using American ginseng (Panax quinquefoliusL.) as our representative less palatable understory plant, we compared two subpopulations within a single natural population that were differentially exposed to browse; one isolated from deer by growing atop a large, flat-topped boulder, and a browse-exposed subpopulation in the surrounding low-lying area. We tested the hypothesis that …

Target Sequence Capture Of Nuclear-Encoded Genes For Phylogenetic Analysis In Ferns, Paul G. Wolf, Tanner A. Robison, Matthew G. Johnson, Michael A. Sundue, Weston L. Testo, Carl J. Rothfels

Biology Faculty Publications

Premise of the Study

Until recently, most phylogenetic studies of ferns were based on chloroplast genes. Evolutionary inferences based on these data can be incomplete because the characters are from a single linkage group and are uniparentally inherited. These limitations are particularly acute in studies of hybridization, which is prevalent in ferns; fern hybrids are common and ferns are able to hybridize across highly diverged lineages, up to 60 million years since divergence in one documented case. However, it not yet clear what effect such hybridization has on fern evolution, in part due to a paucity of available biparentally inherited …

Seed Dormancy-Life Form Profile For 358 Species From The Xishuangbanna Seasonal Tropical Rainforest, Yunnan Province, China Compared To World Database, Qinying Lan, Shouhua Yin, Huiyin He, Yunhong Tan, Qiang Liu, Yongmei Xia, Bin Wen, Carol C. Baskin, Jerry M. Baskin

Biology Faculty Publications

Seed dormancy profiles are available for the major vegetation regions/types on earth. These were constructed using a composite of data from locations within each region. Furthermore, the proportion of species with nondormant (ND) seeds and the five classes of dormancy is available for each life form in each region. Using these data, we asked: will the results be the same if many species from a specific area as opposed to data compiled from many locations are considered? Germination was tested for fresh seeds of 358 species in 95 families from the Xishuangbanna seasonal tropical rainforest (XSTRF): 177 trees, 66 shrubs, …

Mobilization And Role Of Starch, Protein, And Fat Reserves During Seed Germination Of Six Wild Grassland Species, Ming Zhao, Hongxiang Zhang, Hong Yan, Lu Qiu, Carol C. Baskin

Biology Faculty Publications

Since seed reserves can influence seed germination, the quantitative and qualitative differences in seed reserves may relate to the germination characteristics of species. The purpose of our study was to evaluate the correlation between germination and seed reserves, as well as their mobilization during germination of six grassland species (Chloris virgata, Kochia scoparia, Lespedeza hedysaroides, Astragalus adsurgens, Leonurus artemisia, and Dracocephalum moldavica) and compare the results with domesticated species. We measured starch, protein, and fat content in dry seeds and the initial absorption of water during imbibition. Starch, soluble protein, fat, and soluble …

Effects Of Predispersal Insect Seed Predation On The Early Life History Stages Of A Rare Cold Sand-Desert Legume, Yi J. Han, Jerry M. Baskin, Dun Y. Tan, Carol C. Baskin, Ming Y. Wu

Biology Faculty Publications

Seed predation by insects is common in seeds of Fabaceae (legume) species with physical dormancy (PY). However, the consequences of insect seed predation on the life history of legumes with PY have been little studied. In the largest genus of seed plants, Astragalus (Fabaceae), only one study has tested the effects of insect predation on germination, and none has tested it directly on seedling survival. Thus, we tested the effects of insect predation on seed germination and seedling growth and survival of Astragalus lehmannianus, a central Asian sand-desert endemic. Under laboratory conditions, seeds lightly predated in the natural habitat …

Lethal Effects Of Leaf Leachate From The Non-Native Invasive Shrub Amur Honeysuckle (Lonicera Maackii) On A Model Aquatic Organism (Hyalella Azteca), Eric B. Borth, Kevin W. Custer, Ryan W. Mcewan

Biology Faculty Publications

The invasive shrub Lonicera maackii (Amur honeysuckle) is a problematic species in the eastern United States and there is growing evidence that materials from this species have toxic effects on some organisms. We used a sequence of microcosm bioassays to assess the influence of L. maackii leaf leachate on the macroinvertebrate Hyalella azteca, which is a standard aquatic organism for toxicity assessment. In a laboratory setting, H. azteca were exposed to a leaf leachate dilution series (6.25%, 12.5%, 25%, 50%, 100%) in 48-h toxicity tests. This was repeated throughout the growing season to assess the potential for changes in …

The Role Of Environmental Filtering In Structuring Appalachian Tree Communities: Topographic Influences On Functional Diversity Are Mediated Through Soil Characteristics, Julia I. Chapman, Ryan W. Mcewan

Biology Faculty Publications

Identifying the drivers of community assembly has long been a central goal in ecology, and the development of functional diversity indices has provided a new way of detecting the influence of environmental gradients on biotic communities. For an old-growth Appalachian forest, we used path analysis to understand how patterns of tree functional diversity relate to topography and soil gradients and to determine whether topographic effects are mediated through soil chemistry. All of our path models supported the idea of environmental filtering: stressful areas (high elevation, low soil moisture, low soil nutrients) were occupied by communities of low functional diversity, which …

Black Cohosh Seed Germination And Conservation, W. John Hayden

Biology Faculty Publications

Like many plant enthusiasts, I have spent a considerable amount of time planting seeds. Every year I grow many vegetables—my garden always includes some annual bedding plants—and I sow seeds of cover crops (winter wheat, winter rye, and buckwheat) by the tens of thousands. While I have committed vast numbers of propagules to moist soil, I cannot say that I have watched every single one sprout. Nevertheless, I certainly have observed the germination process many, many times for lots of different seeds. For these seeds of garden plants, germination is quite rapid, just a few days to maybe as much …

How Cornus Florida Got Its Name, W. John Hayden

Biology Faculty Publications

In 1753, Swedish botanist Carolus Linnaeus was the first to apply the scientific name Cornus florida to the plant we know as Flowering Dogwood. That simple and straightforward declarative sentence belies the complexity and obscurity of how Linnaeus named this and nearly 6,000 other plants in his seminal work, Species Plantarum. To understand what Linnaeus actually did requires a dive into the arcane world of 18th-century botany. And that is what this article endeavors to accomplish, to explain how Cornus florida, the 2018 VNPS Wildflower of the Year, got its name.

Flowering Dogwood Survives Exotic Attack, W. John Hayden

Biology Faculty Publications

It has been said that loss of native biodiversity from the effects of invasive exotic species is second only to that caused by outright habitat destruction. In the world of plants, some of the worst offenders are exotic species that actively invade intact natural habitats and, by their aggressive tendencies, crowd out native species. Attack by lianas (woody climbing plants) such as Japanese Honeysuckle (Lonicera japonica) and Oriental Bittersweet (Celastrus orbiculatus) can include effects similar to strangulation, brought on by twining around their host plant’s stems. It is not always the host, however, for which the …

Butterfly, Dogwood Linked In Circle Of Life, W. John Hayden, Nicky Staunton

Biology Faculty Publications

What would it be like to live on a diet of nothing but flowers? From the perspective of human nutrition, conventional wisdom suggests that it would be difficult to obtain a well-balanced diet from flowers alone. We do, however, have the legend of the lotus-eaters, people encountered by Odysseus and his crew on their epic return journey from Troy. As recounted in the Odyssey, lotus-eaters lived life in a perpetual stupor, and the two crew members who sampled lotus flowers immediately lost all interest in returning to their homes in Ithaca. Upon seeing the danger of consuming these flowers—the botanical …

Flowering Dogwood, Cornus Florida, 2018 Virginia Wildflower Of The Year, W. John Hayden

Biology Faculty Publications

The Flowering Dogwood is a small understory forest tree attaining heights of 5–15 m. Bark of older trees forms a checkered pattern. Twigs are smooth and range from green to purplish-red. Leaves are opposite, mostly ovate to wide-elliptic, and 6–13 cm long; bases may be rounded or tapered, if the latter, often unequally so; apices are acute to acuminate; vein pattern is pinnate with 4–6 secondary veins on each side of the midvein; secondary veins approaching the leaf margin curve toward the apex; upper and lower leaf surfaces range from glabrous to finely pubescent.