Abstract:
:For more than a century, the common ancestor of flowering plants was thought to have had a seven-celled, eight-nucleate Polygonum-type female gametophyte. It is now evident that not one, but in fact three, patterns of female gametophyte development and mature structure characterize the common ancestors of the four most ancient clades of extant angiosperms: Amborella-type, Nuphar/Schisandra-type and Polygonum-type. The Amborella-type female gametophyte is restricted to a single extant species, Amborella trichopoda, and at maturity consists of eight cells and nine nuclei. Development of the Amborella-type gametophyte is essentially identical to the Polygonum-type except that there is an additional and asynchronous cell division at the micropylar pole prior to maturation that produces a third synergid and the egg cell. The Nuphar/Schisandra-type female gametophyte is four-nucleate and four-celled and at maturity contains a typical three-celled egg apparatus and a central cell with a single haploid polar nucleus. This type of gametophyte appears to be universal among extant members of the Nymphaeales (including Hydatellaceae) and Austrobaileyales. Based on explicit reconstruction of character distribution and evolution, the Polygonum-type female gametophyte is certain to be representative of the common ancestors of monocots, eudicots, magnoliids, Ceratophyllaceae, and Chloranthaceae. There are compelling biological reasons to suggest that the four-celled, four-nucleate female gametophyte (as found in Nymphaeales and Austrobaileyales) is ancestral among angiosperms, with transitions to Polygonum-type female gametophytes separately in the Amborellales and in the ancient angiosperm clade that includes all angiosperms except Amborella, Nymphaeales, and Austrobaileyales. Subsequent to the evolution of a seven-celled, eight-nucleate Polygonum-type female gametophyte in the Amborellales, we hypothesize that a peramorphic increase in egg apparatus cell number took place and led to the unique situation in which there are three synergids in Amborella trichopoda.
journal_name
Am J Botjournal_title
American journal of botanyauthors
Friedman WE,Ryerson KCdoi
10.3732/ajb.0800311subject
Has Abstractpub_date
2009-01-01 00:00:00pages
129-43issue
1eissn
0002-9122issn
1537-2197pii
ajb.0800311journal_volume
96pub_type
杂志文章abstract:PREMISE OF THE STUDY:Self-incompatibility (SI) is a mechanism that prevents inbreeding in many plant species. The mutational breakdown of SI occurs frequently, yet relatively little is known about the evolutionary steps involved in the progressive loss of pistil and pollen SI function. METHODS:In Solanaceae, SI is the...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1600208
更新日期:2016-10-01 00:00:00
abstract::Field surveys of cynipid gall-inducer occurrences on Quercus species were conducted in Florida, North Carolina, and Pennsylvania, USA. All cynipids demonstrated strong host species and organ fidelity. One result of this specialization is effective niche partitioning among cynipids. The host-association patterns of the...
journal_title:American journal of botany
pub_type: 杂志文章
doi:
更新日期:1998-08-01 00:00:00
abstract:PREMISE OF THE STUDY:A prevailing hypothesis in forest succession is that shade-tolerant species grow more slowly than shade-intolerant species, across light conditions, because they prioritize carbon (C) allocation to storage. We examined this hypothesis in a confamilial pair of species, including one of the fastest-g...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1700057
更新日期:2017-05-01 00:00:00
abstract::Senna (Leguminosae) is a large, widespread genus that includes species with enantiostylous, asymmetric flowers and species with extrafloral nectaries. Clarification of phylogenetic relationships within Senna based on parsimony analyses of three chloroplast regions (rpS16, rpL16, and matK) provides new insights on the ...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.93.2.288
更新日期:2006-02-01 00:00:00
abstract::Soybean partial-female-sterile mutant 1 (PS-1) was recovered from a gene-tagging study. The objectives were to study the inheritance, linkage, allelism, and certain aspects of the reproductive biology of the PS-1 mutant. For inheritance and linkage tests, PS-1 was crossed to flower color mutant Harosoy-w4 and to chlor...
journal_title:American journal of botany
pub_type: 杂志文章
doi:
更新日期:1997-06-01 00:00:00
abstract:UNLABELLED:• PREMISE OF THE STUDY:Flower color is one of the best-studied floral traits in terms of its genetic basis and ecological significance, yet few studies have examined the processes that shape its evolution across deep timescales. Advances in comparative methods along with larger phylogenies for floral radiat...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1500163
更新日期:2015-07-01 00:00:00
abstract::Recent discoveries of fossil reproductive structures from deposits of the Raritan Formation in New Jersey (Turonian, Upper Cretaceous, ~90 million years BP) include a previously undescribed representative of the Order Capparales. The fossils are usually charcoalified with three-dimensional structure and excellent anat...
journal_title:American journal of botany
pub_type: 杂志文章
doi:
更新日期:1998-07-01 00:00:00
abstract:PREMISE OF THE STUDY:The fossil record of Agathis historically has been restricted to Australasia. Recently described fossils from the Eocene of Patagonian Argentina showed a broader distribution than found previously, which is reinforced here with a new early Paleocene Agathis species from Patagonia. No previous phylo...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.1002/ajb2.1127
更新日期:2018-08-01 00:00:00
abstract::The biological nature of some symbioses is unclear because it is often not easy to discern whether the symbionts obtain any benefits from the association. Mastodia tessellata, a symbiosis between a leafy green alga and a fungus of uncertain phylogenetic position, is among the most investigated, controversial, and poor...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.0900323
更新日期:2010-05-01 00:00:00
abstract::Microelectrodes were used to study the oxygen concentration within Myrica gale L. nodules. Low oxygen concentrations were found only in the region of the mature, nitrogen-fixing endophyte, and appeared to correspond to clusters of infected host cells. The oxygen concentration in the remainder of the nodule was much hi...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.1002/j.1537-2197.1983.tb12432.x
更新日期:1983-01-01 00:00:00
abstract:PREMISE OF THE STUDY:Anatomical and morphological features of Satanocrater were studied to test hypotheses of xeric adaptations in the genus, which is endemic to arid tropical Africa. These features, together with molecular data, were used to test the phylogenetic placement of Satanocrater within the large plant family...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1100354
更新日期:2012-06-01 00:00:00
abstract::The phylogenetic structure of ferns (= monilophytes) is explored here, with a special focus on the early divergences among leptosporangiate lineages. Despite considerable progress in our understanding of fern relationships, a rigorous and comprehensive analysis of the early leptosporangiate divergences was lacking. Th...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.91.10.1582
更新日期:2004-10-01 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 STUDY:Sequence analyses for Pinaceae have suggested that extant genera diverged in the late Mesozoic. While the fossil record indicates that Pinaceae was highly diverse during the Cretaceous, there are few records of living genera. This description of an anatomically preserved seed cone extends the fossil re...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1100568
更新日期:2012-06-01 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:PREMISE:Although hybridization has played an important role in the evolution of many plant species, phylogenetic reconstructions that include hybridizing lineages have been historically constrained by the available models and data. Restriction-site-associated DNA sequencing (RADseq) has been a popular sequencing techni...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.1002/ajb2.1352
更新日期:2019-09-01 00:00:00
abstract::Extreme preformation, the initiation of leaves or inflorescences more than 1 yr before maturation and function, is common in arctic and alpine habitats. This extended pattern of development provides a potential means to alleviate an apparent asynchrony between carbon supplied by photosynthesis in the summer and carbon...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.90.9.1313
更新日期:2003-09-01 00:00:00
abstract:PREMISE OF THE STUDY:Previous studies have shown that polyploidy has pronounced effects on photosynthesis. Most of these studies have focused on synthetic or recently formed autopolyploids, and comparatively little is known about the integrated effects of natural allopolyploidy, which involves hybridity and genome doub...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1100465
更新日期:2012-01-01 00:00:00
abstract::Restriction fragment length polymorphism (RFLP) analysis of chloroplast (cp) DNA is a powerful tool for the study of microevolutionary processes in land plants, yet has not previously been applied to seaweed populations. We used cpDNA-RFLP, detected on Southern blots using labeled total plastid DNA, to search for intr...
journal_title:American journal of botany
pub_type: 杂志文章
doi:
更新日期:2001-07-01 00:00:00
abstract::We transplanted Nuphar variegata with submersed leaves only into natural lake sediments in pH-, [CO(2)]-, depth-, and temperature-controlled greenhouse tanks to test the hypotheses that more fertile sediment, lower free [CO(2)], and shallower depth would all stimulate the development of floating leaves. Sediment highe...
journal_title:American journal of botany
pub_type: 杂志文章
doi:
更新日期:2001-08-01 00:00:00
abstract::Dispersal is an important life history component. Seed settling velocity may be a useful surrogate for the measurement of dispersal ability in wind-dispersed plants, particularly those whose seeds have plumose dispersal structures. I measured settling velocities on seeds of eight species of Asteraceae, including annua...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.1002/j.1537-2197.1992.tb13702.x
更新日期:1992-10-01 00:00:00
abstract::Species of Collinsia and Tonella, the two sister genera of self-compatible annuals that constitute tribe Collinsieae, show extensive variation in floral size and morphology and in patterns of stamen and style elongation during the life of the flower (anthesis). We used a nuclear ribosomal ITS phylogeny, independent co...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.89.1.37
更新日期:2002-01-01 00:00:00
abstract:PREMISE OF THE STUDY:Bignoniaceae is an important component of neotropical forests and a model for evolutionary and biogeographical studies. A previous combination of molecular markers and morphological traits improved the phylogeny of the group. Here we demonstrate the value of next-generation sequencing (NGS) to asse...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1700302
更新日期:2017-10-01 00:00:00
abstract:UNLABELLED: PREMISE OF THE STUDY:Microsatellite primers were developed in Paeonia lactiflora for further population genetic studies. • METHODS AND RESULTS:Ten dinucleotide microsatellite markers were developed using an enriched genomic library. They were identified in 58 individuals, and nine markers were also amplif...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1100083
更新日期:2011-09-01 00:00:00
abstract::Natural recruitment of oaks appears to be declining throughout the northern hemisphere. Summer drought poses a potentially important barrier to oak recruitment in southern California. To evaluate this barrier, we grew evergreen Quercus agrifolia and deciduous Q. lobata from seeds near parental trees. We measured water...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.0800247
更新日期:2009-04-01 00:00:00
abstract:PREMISE OF THE STUDY:The lycophyte family Selaginellaceae includes approximately 750 herbaceous species worldwide, with the main species richness in the tropics and subtropics. We recently presented a phylogenetic analysis of Selaginellaceae based on DNA sequence data and, with the phylogeny as a framework, the study d...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1600288
更新日期:2016-12-01 00:00:00
abstract:PREMISE OF THE STUDY:Species differ in their temperature germination niche. Populations of a species may similarly differ across the distribution range of the species. Anticipating the impacts of climate variability and change requires understanding the differential sensitivity to germination temperature among and with...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1600278
更新日期:2017-01-01 00:00:00
abstract:PREMISE OF THE STUDY:Elucidating the factors that determine the abundance and distribution of species remains a central goal of ecology. It is well recognized that genetic differences among individual species can affect the distribution and species interactions of dependent taxa, but the ecological effects of genetic d...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1100137
更新日期:2011-10-01 00:00:00
abstract::The anther and ovule development of Camellia, Franklinia, and Schima (Theaceae, Camellioideae) were observed. The three genera share the following embryological traits: anther wall formation of basic type, tapetum of glandular type, walls of endothecial cells with secondary thickening, and production of pseudopollen g...
journal_title:American journal of botany
pub_type: 杂志文章
doi:
更新日期:1997-03-01 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