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American Journal of Botany | Page 2

Laura D Porturas, Thomas J Anneberg, Anne E Curé, Shengpei Wang, David M Althoff, Kari A Segraves
PREMISE OF THE STUDY: Polyploidy, or whole genome duplication (WGD), is common in plants despite theory suggesting that polyploid establishment is challenging and polyploids should be evolutionarily transitory. There is renewed interest in understanding the mechanisms that could facilitate polyploid establishment and explain their pervasiveness in nature. In particular, premating isolation from their diploid progenitors is suggested to be a crucial factor. To evaluate how changes in assortative mating occur, we need to understand the phenotypic effects of WGD on reproductive traits...
March 22, 2019: American Journal of Botany
Katharine J Zlonis, Julie R Etterson
PREMISE OF THE STUDY: Polyploids possess unique attributes that influence their environmental tolerance and geographic distribution. It is often unknown, however, whether cytotypes within mixed-ploidy populations are also uniquely adapted and differ in their responses to environmental change. Here, we examine whether diploids and hexaploids from a single mixed-ploidy population of Solidago altissima differ in plasticity and potential response to natural selection under conditions simulating climate change...
March 22, 2019: American Journal of Botany
Kristen Peach, Susan J Mazer
PREMISE OF THE STUDY: Wild plant species that require the services of pollen-feeding insects for reliable pollination may evolve features that attract and reward their mutualistic partners. Heterantherous species have been proposed to exhibit a "division of labor" whereby "feeding anthers" (which produce pollen that may be consumed by an insect) are distinguished from "reproductive anthers" (which produce pollen more likely to contribute to reproduction)...
March 22, 2019: American Journal of Botany
Ryan S Fuller, Mitchell E McGlaughlin
PREMISE OF THE STUDY: Climate cycles of the Quaternary have impacted plants at a global scale, leaving behind a complex genetic legacy. Species of the northern Rocky Mountains of North America were exposed to more uniform glacial patterns than the central and southern ranges, where synergistic relationships between temperature and precipitation caused differences in the timing and extent of glacier onset. We examined the genetic impacts of climate oscillations on Calochortus gunnisonii (Liliaceae) in the central and southern Rocky Mountains...
March 22, 2019: American Journal of Botany
Rupesh R Kariyat, Andrew G Stephenson
No abstract text is available yet for this article.
March 21, 2019: American Journal of Botany
(no author information available yet)
No abstract text is available yet for this article.
March 21, 2019: American Journal of Botany
Edward J Primka, William K Smith
PREMISE OF THE STUDY: Deciduous tree species remove some nutrients from their leaves during fall leaf senescence through retranslocation. Retranslocation impacts the timeline of leaf fall, amount of active chlorophyll, and overall leaf nitrogen content as fall color change occurs. Our objective was to identify interspecific differences in the timing of abscission layer formation, leaf color change, and the level of chlorophyll degradation of young trees during fall senescence. METHODS: Leaf relative chlorophyll content for three tree species was measured during fall 2015 by a greenness meter...
March 18, 2019: American Journal of Botany
Diego F Morales-Briones, David C Tank
PREMISE OF THE STUDY: Polyploidy has been long recognized as an important force in plant evolution. Previous studies had suggested widespread occurrence of polyploidy and the allopolyploid origin of several species in the diverse neotropical genus Lachemilla (Rosaceae). Nonetheless, this evidence has relied mostly on patterns of cytonuclear discordance, and direct evidence from nuclear allelic markers is still needed. METHODS: Here we used PCR target enrichment in combination with high throughput sequencing to obtain multiple copies of the nuclear ribosomal (nr) DNA cistron and 45 regions of the plastid genome (cpDNA) from 219 accessions representing 48 species of Lachemilla and to explore the allopolyploid origin of species in this group...
March 18, 2019: American Journal of Botany
Michael J Donoghue, Erika J Edwards
No abstract text is available yet for this article.
March 18, 2019: American Journal of Botany
Giseli D Pedersoli, Flávia M Leme, Viviane G Leite, Simone P Teixeira
PREMISE OF THE STUDY: This study details the unusual synorganization of the staminate flower in wind-pollinated urticalean rosids to add the missing pieces that complete the puzzle of the explosive mechanism of pollen release in this group. METHODS: Flower buds and flowers were analyzed using light and scanning electron microscopy. KEY RESULTS: The pistillode, stamens, and sepals form a floral apparatus that explosively releases pollen to be carried by the wind...
March 15, 2019: American Journal of Botany
La-Mei Wu, Si-Chong Chen, Bo Wang
PREMISE OF THE STUDY: Numerous studies have treated the mass of a whole seed as an integrated unit, although the components seed kernel and seed coat play different roles and are subject to different evolutionary selection pressures. In this study, we provided the first global-scale quantification of the relative biomass investments in seed coats and seed kernels. We tested the following hypotheses: there is a negative allometry between seed kernel mass and seed coat mass, and therefore, seed coat ratio (SCR) is negatively correlated with seed mass...
March 13, 2019: American Journal of Botany
David Livingston, Tan Tuong, Marco Nogueira, Thomas Sinclair
PREMISE OF THE STUDY: In many cases, the functioning of a biological system cannot be correctly understood if its physical anatomy is incorrectly described. Accurate knowledge of the anatomy of soybean [Glycine max (L.) Merril] nodules and its connection with the root vasculature is important for understanding its function in supplying the plant with nitrogenous compounds. Previous two-dimensional anatomical observations of soybean nodules led to the assumption that vascular bundles terminate within the cortex of the nodule and that a single vascular bundle connects the nodule to the root...
March 12, 2019: American Journal of Botany
Ana Otero, Pedro Jiménez-Mejías, Virginia Valcárcel, Pablo Vargas
PREMISE OF THE STUDY: Long-distance dispersal (LDD) syndromes, especially endozoochory, facilitate plant colonization of new territories that trigger diversification. However, few studies have analyzed how epizoochorous fruits influence both range distribution and diversification rates. We examined the evolutionary history of a hyperdiverse clade of Boraginaceae (subfamily Cynoglossoideae, eight tribes, ~60 genera, ~1100 species) and the evolution of fruit traits. We evaluated the evolutionary history of diaspore syndromes correlated with geographic distribution and diversification rates over time...
March 12, 2019: American Journal of Botany
Huiyuan Peng, Zhengbing Yan, Yahan Chen, Xujian Zhao, Wenxuan Han
PREMISE OF THE STUDY: Nutrient resorption is essential for plant nutrient conservation. Large-bodied plants potentially have large nutrient sink pools and high nutrient flux. Whether and how nutrient resorption can be regulated by plant size and biomass allocation are yet unknown. METHODS: Using the herbaceous plant Amaranthus mangostanus in greenhouse experiments for two consecutive years, we measured plant biomass, height, and stem diameter and calculated the root to shoot biomass ratio (R/S ratio) and nutrient resorption efficiency (NuRE) to assess the effects of plant body size and biomass allocation on NuRE...
March 12, 2019: American Journal of Botany
Brian Park, Michael J Donoghue
PREMISE OF THE STUDY: There have been relatively few phylogeographic studies of eastern North American plants, especially of animal-dispersed shrubby species, and this leaves a significant gap in our understanding of how such species were affected by glacial events. Here, we analyzed the phylogeography of the widespread understory shrub Viburnum lantanoides. METHODS: We generated RADseq data and paleoclimatic species distribution models (SDMs) to identify the locations of refugia where V...
March 12, 2019: American Journal of Botany
Daniel L Nickrent, Frank Anderson, Job Kuijt
PREMISE OF THE STUDY: The sandalwood order (Santalales) includes members that present a diverse array of inflorescence types, some of which are unique among angiosperms. This diversity presents not only interpretational challenges but also opportunities to test fundamental concepts in plant morphology. Here we used modern phylogenetic approaches to address the evolution of inflorescences in the sandalwood order. METHODS: Phylogenetic analyses of two nuclear and three chloroplast genes were conducted on representatives of 146 of the 163 genera in the order...
March 11, 2019: American Journal of Botany
Yesenia Madrigal, Juan Fernando Alzate, Favio González, Natalia Pabón-Mora
PREMISE OF THE STUDY: Bilateral symmetry in core eudicot flowers is established by the differential expression of CYCLOIDEA (CYC), DICHOTOMA (DICH), and RADIALIS (RAD), which are restricted to the dorsal portion of the flower, and DIVARICATA (DIV), restricted to the ventral and lateral petals. Little is known regarding the evolution of these gene lineages in non-core eudicots, and there are no reports on gene expression that can be used to assess whether the network predates the diversification of core eudicots...
March 7, 2019: American Journal of Botany
Heidi Hirsch, Maria L Castillo, Fiona A C Impson, Catharina Kleinjan, David M Richardson, Johannes J Le Roux
PREMISE OF THE STUDY: Knowledge about the introduction history (source(s), number and size of introduction events) of an invasive species is a crucial prerequisite to understand invasion success and to facilitate effective and sustainable management approaches, especially for effective biological control. We investigated the introduction history of the Australian legume tree Acacia dealbata in South Africa. Results of this study will not only provide critical information for the management of this species in South Africa, but will also broaden our overall knowledge on the invasion ecology of this globally important invasive tree...
February 28, 2019: American Journal of Botany
Juan M Losada, N Michele Holbrook
PREMISE OF THE STUDY: Recent studies in canopy-dominant trees revealed axial scaling of phloem structure. However, whether this pattern is found in woody plants of the understory, the environment of most angiosperms from the ANA grade (Amborellales-Nymphaeales-Austrobaileyales), is unknown. METHODS: We used seedlings and adult plants of the understory tropical shrub Illicium parviflorum, a member of the lineage Austrobaileyales, to explore the anatomy and physiology of the phloem in their aerial parts, including changes through ontogeny...
February 21, 2019: American Journal of Botany
(no author information available yet)
No abstract text is available yet for this article.
February 21, 2019: American Journal of Botany
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