Abstract:
:We developed an improved cytological protocol for producing high quality, light microscope images of plant meiotic chromosomes. Because the technique works on species with small genomes and thick microsporocyte cell walls, it should be useful for studying the wild relatives of Arabidopsis and other eudicots with small genomes. Combining this improved fixation protocol with our new analysis of associated substages in floral buds, we can unambiguously assign individual meiotic cells to particular substages of prophase I in Arabidopsis thaliana, even for difficult distinctions such as that between late zygotene or early diplotene. In this report we provide the first estimate of the individual duration of the zygotene and pachytene substages (4.8 h and 10.0 h, respectively) in A. thaliana. We also have examined the diffuse substage of prophase I and report that during this post-pachytene substage, nuclei retain the association of homologous nucleolus organizer regions and homologous centromeres, despite the generally diffuse chromatin and generally unpaired chromosome regions. Additionally, we have observed that centromeric regions of the chromosomes of diffuse-stage nuclei are highly condensed, more so than those of any other substage of prophase I.
journal_name
Am J Botjournal_title
American journal of botanyauthors
Stronghill PE,Hasenkampf CAdoi
10.3732/ajb.94.12.2063subject
Has Abstractpub_date
2007-12-01 00:00:00pages
2063-7issue
12eissn
0002-9122issn
1537-2197pii
94/12/2063journal_volume
94pub_type
杂志文章abstract::Phloem, as a major tissue mediating long-distance communication, has been an object of extensive research ever since its structure was first reported in 1837. Functional phloem consists of sieve elements (SEs) and companion cells (CCs). While SEs are enucleated conducting cells in the phloem, CCs are cells with intact...
journal_title:American journal of botany
pub_type: 杂志文章,评审
doi:10.3732/ajb.1400197
更新日期:2014-09-01 00:00:00
abstract::The North American plums are a closely related group that are not easily circumscribed, have overlapping morphologies, and are known to hybridize. We previously showed that the North American plums are a closely related, monophyletic group of taxa with little to no cpDNA sequence divergence between taxa. In that study...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.92.12.2011
更新日期:2005-12-01 00:00:00
abstract:UNLABELLED: PREMISE OF THE STUDY:The Malpighiaceae include ∼1300 tropical flowering plant species in which generic definitions and intergeneric relationships have long been problematic. The goals of our study were to resolve relationships among the 11 generic segregates from the New World genus Mascagnia, test the mon...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1000146
更新日期:2010-12-01 00:00:00
abstract::Intensified ultraviolet-B radiation or UV-B (wavelengths between 280 and 320 nm) can delay flowering and diminish lifetime flower production in a few plants. Here we studied the effects of enhanced UV-B on floral traits crucial to pollination and pollinator reproduction. We observed simultaneous flowering responses of...
journal_title:American journal of botany
pub_type: 杂志文章
doi:
更新日期:1999-01-01 00:00:00
abstract:PREMISE OF THE STUDY:Eocene caldera-lake beds at Laguna del Hunco (LH, ca. 52.2 Ma) and Río Pichileufú (RP, ca. 47.7 Ma) in Argentine Patagonia provide copious information about the biological history of Gondwana. Several plant genera from these sites are known as fossils from southern Australia and New Zealand and sur...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1100367
更新日期:2012-03-01 00:00:00
abstract::Multicellularity has evolved at least once in every major eukaryotic clade (in all ploidy levels) and numerous times among the prokaryotes. According to a standard multilevel selection (MLS) model, in each case, the evolution of multicellularity required the acquisition of cell-cell adhesion, communication, cooperatio...
journal_title:American journal of botany
pub_type: 杂志文章,评审
doi:10.3732/ajb.1300314
更新日期:2014-01-01 00:00:00
abstract::Biparental inbreeding is thought to be a common feature of plant populations with restricted pollen dispersal. It is generally assumed that the inbreeding depression frequently observed to accompany self-fertilization can be extrapolated to the lesser degrees of consanguinity involved in biparental inbreeding, but thi...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.1002/j.1537-2197.1993.tb13838.x
更新日期:1993-05-01 00:00:00
abstract:PREMISE OF THE STUDY:Cryptic species are superficially morphologically indistinguishable and therefore erroneously classified under one single name. The identification and delimitation of these species is usually a difficult task. The main aim of this study is to provide an inclusive methodology that combines standard ...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1000438
更新日期:2011-06-01 00:00:00
abstract:PREMISE OF THE STUDY:Tetraena simplex is an independently evolved C4 species in the Zygophylloideae (Zygophyllaceae) and a characteristic forb of saline flats in hot and sandy desert habitats. During early ontogeny, the species had a morphological shift from planar cotyledons (dorsiventral symmetry) to terete, succulen...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.1002/ajb2.1087
更新日期:2018-05-01 00:00:00
abstract::Nuclear DNA contents (4C) were estimated by Feulgen microdensitometry in 27 species of slipper orchids. These data and recent information concerning the molecular systematics of Cypripedioideae allow an interesting re-evaluation of karyotype and genome size variation among slipper orchids in a phylogenetic context. DN...
journal_title:American journal of botany
pub_type: 杂志文章
doi:
更新日期:1998-05-01 00:00:00
abstract:PREMISE:Despite the efforts to understand the processes that shape neotropical biodiversity, the complexity of certain biomes, such as the Atlantic Forest (AF), prevents the generalization of patterns. Initially, ecological niche modeling (ENM), with phylogeographic studies, identified past stable areas in the central ...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.1002/ajb2.1317
更新日期:2019-07-01 00:00:00
abstract::Several alpine species have outlying populations in the lowlands and lower mountains north of the Alps. These small, isolated populations are usually described as either (1) glacial relics, (2) descendants from populations living on forelands and moraines during the ice ages, or (3) populations founded by long-distanc...
journal_title:American journal of botany
pub_type: 杂志文章
doi:
更新日期:2000-04-01 00:00:00
abstract:PREMISE OF THE STUDY:Despite being highly fertile and occupying a large geographic region, the North American heartleaf bittercress (Cardamine cordifolia; Brassicaceae) has a puzzling triploid-like chromosome number (2n = 3x = 24). As most triploids are sterile, we embarked on a detailed analysis of the C. cordifolia g...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1500452
更新日期:2016-07-01 00:00:00
abstract::Seeds are useful in distinguishing among extant genera of Vitaceae and provide a good basis for interpretation of fossil remains in reconstructing the evolutionary and phytogeographic history of this putatively basal Rosid family. Seeds of Ampelocissus s.l. including Pterisanthes and Nothocissus are distinguished from...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.94.9.1534
更新日期:2007-09-01 00:00:00
abstract:PREMISE OF THE STUDY:The correct assessment of homology is an important prerequisite for reconstructing phylogenetic relationships and character evolution. Old World Papaveroideae (Papaver, Meconopsis, Roemeria, Stylomecon) show substantial diversity in gynoecium and capsule morphology. In particular, capsules can have...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1100066
更新日期:2011-08-01 00:00:00
abstract:PREMISE OF THE STUDY:Uplift of the tropical Andes had a significant impact on the diversification of South American flora and fauna. Recent biogeographic inquiries have established patterns of Andean divergence, but investigations on ferns are scant. The fern genus Polystichum Roth (Dryopteridaceae) combines widespread...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1300191
更新日期:2014-02-01 00:00:00
abstract: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 Ama...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.1002/ajb2.1246
更新日期:2019-03-01 00:00:00
abstract::Floral morphology of the 13 species of Moringa ranges from actinomorphic flowers with little hypanthium to highly zygomorphic flowers with well-developed hypanthia. Scanning electron and light microscopy were used to identify ontogenetic differences among two actinomorphic and eight zygomorphic species. All species sh...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.90.1.49
更新日期:2003-01-01 00:00:00
abstract::Xylem of the orchids studied provided unusually favorable material to demonstrate how conductive tissue evolves in monocotyledons. In the end walls of tracheary elements of many Orchidaceae, remnants of pit membranes were observed with scanning electron microscopy and minimally destructive methods. The full range from...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.93.7.963
更新日期:2006-07-01 00:00:00
abstract:PREMISE OF THE STUDY:Giant cacti species possess long cylindrical stems that store massive amounts of water and other resources to draw on for photosynthesis, growth, and reproduction during hot and dry conditions. Across all giant cacti taxa, stem photosynthetic surface area to volume ratio (S:V) varies by several fol...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.1002/ajb2.1166
更新日期:2018-10-01 00:00:00
abstract::We investigated the possible effect of recent (1927-1995) increases in the concentration of atmospheric CO2 on the stomatal densities of leaves of a wide range of tree, shrub, and herb species (N = 60) by making new measurements for comparison with corresponding data reported by E. J. Salisbury in 1927--a time when ic...
journal_title:American journal of botany
pub_type: 杂志文章
doi:
更新日期:1997-11-01 00:00:00
abstract:PREMISE OF THE STUDY:Fossilized seeds similar to Cissus (Vitaceae) have been recognized from the Miocene of Kenya, though some were previously assigned to the Menispermaceae. We undertook a comparative survey of extant African Cissus seeds to identify the fossils and consider their implications for the evolution and bi...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1600177
更新日期:2016-09-01 00:00:00
abstract:PREMISE OF THE STUDY:Species formation is an intuitive endpoint of reproductive isolation, but circumscribing taxa that arise during speciation can be difficult because of gene flow, morphological continuity, hybridization or polyploidization, and low sequence variation among newly diverged lineages. Nonetheless, speci...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.1002/ajb2.1061
更新日期:2018-03-01 00:00:00
abstract:PREMISE OF THE STUDY:The presence or absence of a functional copy of a plastid gene may reflect relaxed selection, and may be phylogenetically significant, reflecting shared ancestry. In some liverworts, the plastid gene cysA is a pseudogene (inferred to be nonfunctional). We surveyed 63 liverworts from all major clade...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1100010
更新日期:2011-08-01 00:00:00
abstract::A conspicuous feature of Vochysiaceae flowers is their single fertile stamen. In some genera, the stamen is in front of a petal, whereas in others it is in front of a sepal. This difference has been attributed to two independent reductions, which implies the stamen is not homologous across the family. The observation ...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.90.11.1548
更新日期:2003-11-01 00:00:00
abstract:PREMISE OF THE STUDY:Bio-ontologies are essential tools for accessing and analyzing the rapidly growing pool of plant genomic and phenomic data. Ontologies provide structured vocabularies to support consistent aggregation of data and a semantic framework for automated analyses and reasoning. They are a key component of...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1200222
更新日期:2012-08-01 00:00:00
abstract:PREMISE OF THE STUDY:We developed simple sequence repeat (SSR) markers from expressed sequence tags (ESTs) for Callitris columellaris sensu lato (s.l.) to elucidate population genetic structure and detect outlier loci by genome scan. METHODS AND RESULTS:mRNA from an individual seedling was subjected to cDNA synthesis ...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1100276
更新日期:2011-12-01 00:00:00
abstract::Iris cristata and I. lacustris differ markedly in geographic distribution, glacial history of current ranges, and ecology. We hypothesized that I. cristata, a widespread species of unglaciated regions of eastern North America, would exhibit genetic diversity typical of other widespread plant species, whereas the threa...
journal_title:American journal of botany
pub_type: 杂志文章
doi:
更新日期:2000-03-01 00:00:00
abstract::This study shows that structural data, when carefully examined, can provide valuable characters for delimiting monophyletic groups and can complement DNA with observable features to recognize and circumscribe taxa. In the angiosperm order Apiales, traditional classification has relied heavily (often exclusively) on fr...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.93.9.1357
更新日期:2006-09-01 00:00:00
abstract::Light propagation and distribution inside leaves have been recognized as important processes influencing photosynthesis. Monochromatic light absorption across the mesophyll was measured using chlorophyll fluorescence generated from illumination of the cut edge (epi-illumination), as well as the adaxial or abaxial surf...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.92.9.1425
更新日期:2005-09-01 00:00:00