Seed Coat Anatomy Research Articles

Oldest fruits of the grape family (Vitaceae) from the Late Cretaceous Deccan Cherts of India

Despite the inferred Cretaceous origin of the Vitaceae, fossils of the grape family are relatively young, with the oldest previously known examples limited to the Paleocene of Europe and North America. New fossil evidence indicates that the family was already present in India in the Late Cretaceous (Maastrichtian), about 10-15 million years before the tectonic collision of India with Eurasia. • Fruits and seeds were investigated by serial sections and peels of chert from the Deccan Intertrappean beds of central India, and compared anatomically with those of extant genera. • Indovitis chitaleyae gen. et sp. n. is described based on immature fruits bearing four to six seeds, and isolated mature seeds. The seeds possess paired ventral infolds and a dorsal chalaza, features diagnostic of the order Vitales. Characters of chalaza shape, infold morphology, and seed coat anatomy place I. chitaleyae within Vitaceae and favor a phylogenetic position either sister to the Vitis-Ampelocissus clade or sister to the Ampelopsis-Clematicissus-Rhoicissus clade. • Presence of the oldest known vitaceous fossils in the latest Cretaceous of India indicates a previously undocumented Gondwanan history and a possible southern hemisphere origin for the Vitales. An "out-of-India" scenario might explain the relatively sudden appearance of diverse Vitaceae in the Late Paleocene and Early Eocene of the Northern Hemisphere.

A combined histology and transcriptome analysis unravels novel questions on Medicago truncatula seed coat

The seed coat is involved in the determination of seed quality traits such as seed size, seed composition, seed permeability, and hormonal regulation. Understanding seed coat structure is therefore a prerequisite to deciphering the genetic mechanisms that govern seed coat functions. By combining histological and transcriptomic data analyses, cellular and molecular events occurring during Medicago truncatula seed coat development were dissected in order to relate structure to function and pinpoint target genes potentially involved in seed coat traits controlling final seed quality traits. The analyses revealed the complexity of the seed coat transcriptome, which contains >30 000 genes. In parallel, a set of genes showing a preferential expression in seed coat that may be involved in more specific functions was identified. The study describes how seed coat anatomy and morphological changes affect final seed quality such as seed size, seed composition, seed permeability, and hormonal regulation. Putative regulator genes of different processes have been identified as potential candidates for further functional genomic studies to improve agronomical seed traits. The study also raises new questions concerning the implication of seed coat endopolyploidy in cell expansion and the participation of the seed coat in de novo abscisic acid biosynthesis at early seed filling.

Investigation of genome polymorphism and seed coat anatomy of species of section Adenolinum from the genus Linum

Twelve species of section Adenolinum from genus Linum have been studied using cytogenetic methods (DAPI/C-banding, Ag-NOR staining, FISH with 5S and 26S rDNA probes), RAPD analysis, and seed surface ultrastructure and seed coat anatomy investigation. Karyotype analysis revealed that these species have a chromosome number of 2n = 18 or 2n = 36. The DAPI/C-banding patterns enabled the identification of all chromosomes and revealed the similarities in chromosome patterns in all of the studied species. It was found that 18-chromosome plants are diploids, whereas 36-chromosome forms are tetraploids. In diploid species, 5S and 26S rRNA genes are located in similar positions on a single pair of chromosomes or on two chromosome pairs in tetraploids. Ag-NOR staining showed NOR activity in both genomes of tetraploids. RAPD analysis and seed coat anatomy investigation revealed some interspecies differences. Species from nearby areas have more similar RAPD characteristics compared with more geographically distant species. The results of this study may serve as an additional argument in favour of a monophyletic origination of the Adenolinum species and its strong isolation from other Linum species.

Seed Morphology of Vitaceae

Seeds of Vitaceae can be easily recognized by their unique features, a pair of ventral infolds and a dorsal chalaza knot, but the inter- and intrageneric morphological variation in seed morphology has not been explored in detail. To facilitate identification of genera based on seed morphology, a study of 252 extant seeds representing all 15 genera of Vitaceae was conducted with attention to morphological characters and seed coat anatomy. Principal-component analyses were employed to assess the variation of seed morphology. Shape and position of ventral infolds and chalaza, shape of ventral-infold cavities, and testa anatomy are characters that can generically differentiate vitaceous seeds. Typically, seeds of Leea, Cissus, Cyphostemma, Tetrastigma, Rhoicissus, and Cayratia have a long or linear chalaza, whereas those of the rest of the family usually have an oval chalaza. Nevertheless, some seed forms occur in more than one genus, and some genera possess more than one seed form. The overlapping seed morph...

Fruits and Seeds of theValerianaClade (Dipsacales): Diversity and Evolution

Recent molecular investigations have greatly improved our understanding of the phylogenetic relationships of the Valeriana clade. Our investigation of the fruits and seeds of the Valeriana clade provides morphological support for these findings. In particular, seed anatomy, calyx morphology, the presence of sterile locules, and fruit polymorphism provide support for the major lineages in the Valeriana clade (i.e., Valerianaceae). Fruit and seed morphology and anatomy of all genera but Nardostachys were investigated. Our results indicate that an important shift in seed anatomy took place at the origin of the core valerians (i.e., Valerianeae), including the loss of endosperm and a shift in seed coat anatomy. Furthermore, our data suggest that the evolution toward polymorphic fruits occurred at least twice, once at the origin of the clade holding Fedia and Valerianella and a second time at the inception of Plectritis. Our sampling indicates that the loss of sterile locules in mature achenes took place along the branch leading to Centranthus, Plectritis, and Valeriana. To confirm this, it will be necessary to examine South and Central American Valeriana species.

Recalcitrancy and a new kind of epicotyl dormancy in seeds of the understory tropical rainforest tree Humboldtia laurifolia (Fabaceae, Ceasalpinioideae)

We report a new kind of seed dormancy and identify the storage behavior category for an important understory rainforest tree that also is used as an ornamental. While studying seed dormancy of Fabaceae species in Sri Lanka, we observed a considerable delay in emergence of the plumule following radicle emergence in Humboldtia laurifolia. Because epicotyl dormancy has not been reported in Fabaceae, we undertook a detailed morphological study of seed germination in this species. Our aims were to document desiccation tolerance/intolerance and epicotyl dormancy in seeds of H. laurifolia. Drying and low temperature storage were used to evaluate storage behavior of the seeds and imbibition, germination, and seed coat anatomy to categorize seed dormancy in two seed collections. Plumule development before its emergence and effects of light and temperature on plumule emergence were monitored. All seeds that were dried to 15% moisture content or stored at -1°C lost viability. Plumules began to grow 20 ± 5 d from radicle emergence and emerged after 40 ± 3 d. Dark and high illuminance further delayed plumule emergence. Seeds are recalcitrant and have a hitherto unreported kind of epicotyl dormancy, for which we propose the formula .

Polyphenol Oxidase Activity and Differential Accumulation of Polyphenolics in Seed Coats of Pinto Bean (Phaseolus vulgaris L.) Characterize Postharvest Color Changes

Postharvest darkening of pinto bean (Phaseolus vulgaris L.) was evaluated in a population of recombinant inbred lines derived from a cross between CDC Pintium (a regular-darkening line) and 1533-15 (a slow-darkening line). Flavonoid metabolite concentrations, polyphenol oxidase activity, lignin concentration, and seed coat anatomy characteristics were assessed for cosegregation with the darkening phenotype. Significantly lower kaempferol concentrations (p = 0.00001) together with differences in polyphenol oxidase activity (p = 0.0045) were two of the key findings associated with these recombinant inbred lines. In addition, two different assays (thioglycolic acid and Klason lignin) to quantify lignin together with an assessment of extractable condensed tannin were used to estimate the contribution of these polymers to changes in the seed coat tissue. This is the first report of precise biochemical characterization of polyphenolics that associate with postharvest darkening in legumes.

Physical Dormancy in Seeds of the Holoparasitic Angiosperm Cuscuta australis (Convolvulaceae, Cuscuteae): Dormancy-breaking Requirements, Anatomy of the Water Gap and Sensitivity Cycling

Dormancy in seeds of Cuscuta (Convolvulaceae, tribe Cuscuteae) is due to a water-impermeable seed coat (physical dormancy). In nondormant seeds of several species of this family, bulges adjacent to the micropyle have been identified as the initial route of water entry into seeds (water gap). However, there are claims that water enters seeds of Cuscuta spp. via the entire seed coat. Although several studies have been done on seed coat anatomy of Cuscuta, none has identified and/or characterized the morphology/anatomy of a water gap. Thus, the primary aim of this research was to identify and describe the morphology and anatomy of the water gap in seeds of Cuscuta australis. It was also determined if sensitivity cycling to dormancy-breaking treatments occurs in seeds of this species. Light microscopy, scanning electron microscopy, tissue-sectioning and dye-tracking and blocking experiments were used to investigate the morphology and anatomy of the water gap. Treatments simulating natural conditions were used to break seed dormancy. Storage of seeds at different temperatures was tested for their effect on sensitivity to dormancy-breaking treatment. Dormancy-breaking treatments caused the tightly closed hilar fissure to open. Staining was observed in cells below the hilum area but not in those below the seed coat away from the hilum. Sensitivity to dormancy-breaking treatment was induced by storing seeds dry and reduced by storing them wet. Whereas bulges adjacent to the micropyle act as the water gap in other species of Convolvulaceae with physical dormancy, the hilar fissure serves this function in Cuscuta. Cuscuta australis can cycle between insensitivity <--> sensitivity to dormancy-breaking treatments.

Evolution and Phylogenetic Importance of Endocarp and Seed Characters inViburnum(Adoxaceae)

Recent phylogenetic analyses based on molecular markers have resulted in a solid phylogeny of Viburnum with 12 well-defined clades. This has allowed us to focus on character evolution, endocarp and seed characters in particular. Members of Viburnum bear drupes that differ considerably between clades. Characters such as pyrene shape and grooving, number of fibrous layers, seed coat anatomy, and seed rumination are phylogenetically highly valuable. Our results largely agree with the results based on molecular data and provide several additional insights. The position of V. clemensae as sister to the rest of Viburnum is supported by several characters. The early diversification of V. clemensae might explain its highly derived features. Furthermore, our results give an indication of the possible paraphyly of the Megalotinus clade, confirm the paraphyly of Hara’s section Solenotinus, and support the split of Hara’s section Odontotinus into four well-defined clades. Endocarp and seed characters are mainly useful at the level of individual clades. Several characters, however, are useful at higher taxonomic levels. The presence of small, amorphous crystals in the endosperm, for example, is most likely to be apomorphic for Viburnum within the order Dipsacales.

Influência do envelhecimento acelerado na anatomia da testa de sementes de soja, cv. Monsoy 8400

Durante o processo de envelhecimento, as sementes sofrem alterações degenerativas que influenciam o seu potencial fisiológico. Entre estas alterações podem estar as modificações anatômicas nas camadas celulares da testa da semente. Objetivou-se, com este trabalho, verificar a relação entre a anatomia da testa de sementes de soja, cultivar Monsoy 8400 e a germinação, após o envelhecimento acelerado, pelo fato da testa apresentar um papel fundamental na conservação do potencial fisiológico das sementes. As sementes foram envelhecidas a 42ºC e 100% UR do ar por períodos de zero, 24, 48, 72 e 96 horas. Avaliaram-se os teores de água e a germinação, posteriormente à secagem, seções transversais da testa de 10 sementes de cada tratamento foram eletromicrografadas, com microscópio eletrônico de varredura,,observando-se as camadas das células paliçádicas, ampulhetas e parenquimáticas A germinação declinou com o aumento dos períodos de envelhecimento. Houve redução da espessura das camadas da testa nos períodos de 48, 72 e 96 horas deste processo. Observou-se que, principalmente, para os períodos de envelhecimento de 72 e 96 horas, que as células da camada hipodérmica apresentaram um aspecto de colapso, sendo este acentuado para o período de 96 horas. A redução da espessura das camadas sugere a ocorrência de um colapso das células que compõem tais camadas, sendo um fator causador da redução do potencial germinativo.

Morfología de la semilla y anatomía de la cubierta seminal de cinco especies de Calliandra (Leguminosae-Mimosoideae) de Venezuela

Calliandra is an exclusively Neotropoical genus with 135 described species. There are 30 species in Venezuela. We studied seed morphology and the seed coat anatomy of five species: Calliandra riparia Pittier, Calliandra glomerulata Karsten var. glomerulata, Calliandra magdalenae (DC.) Bentk var. magdalenae, Calliandra surinamensis Benth and Calliandra falcata Benth., to establish simililarities and differences amongst taxa for taxonomic characterization. Of the evaluated characters, 10 quantitative characters and 3 qualitative characters were selected as the most informative for the separation of species. Seed morphological characters of taxonomic value are form and size. Thickness of the light line, number of layers and space between the osteosclereids constitute distinctive characters.

A revision of Martin's seed classification system, with particular reference to his dwarf-seed type

AbstractMartin's (1946) seed classification system has 10 types based on embryo and endosperm characteristics and two additional types based on seed size: dwarf (0.3–2.0 mm) and micro ( ≤ 0.2 mm). He listed 17 families and 12 genera (in five other families) as having dwarf seeds. Our recent discovery of morphophysiological dormancy in dwarf seeds of several taxa ofCampanulaceaeand one ofGentianaceaeprompted an evaluation of dwarf seeds. Martin's paper contains 37 families with one to several small (0.3–2.0 mm) seeded species that he did not list as being dwarf. Comparison of Martin's dwarf families and the 37 small-seeded non-dwarf families revealed no consistent differences between the two groups in endosperm texture, seed-coat anatomy, embryo morphology, class of seed dormancy or phylogenetic position. Also, Martin's dwarf seeds include a variety of embryo morphologies. Consequently, we have revised Martin's key to seed types. The dwarf category has been removed and the micro category replaced by ‘undifferentiated’ to reflect the state of the embryo in fresh seeds. Further, the key now includes linear fully developed, linear underdeveloped, spatulate fully developed and spatulate underdeveloped seed types, which Martin illustrated but did not include in his key. In the revised key, all seeds are distinguished on the basis of embryo and endosperm characteristics.

A new species of Noccaea (Brassicaceae) from South Anatolia, Turkey

Noccaea camlikensis sp. nov. (Brassicaceae) is described and illustrated from a localized serpentine range in southern Turkey. Its close relationship to N. cariensis, from which it differs in leaf and carpological characters, is discussed. The protologue of this fairly unknown species can now be amended to cover better the morphological variability of this taxon. A comparative study of seed-coat anatomy advocates its move from Thlaspi to Noccaea; the relevant combination N. cariensis (Carlström) Parolly, Nordt & Aytaç is made. The ecology of both vicarious species is discussed and their distribution mapped.

Taxonomic significance of the seed characters of certain species of tribe Asclepiadeae in Egypt

Seed external morphology and coat anatomy of ten species of tribeAsclepiadeae (Asclepiadoideae-Apocynaceae) in Egypt are investigated usingLight Microscope (LM) and Scanning Electron Microscope (SEM). Seedfeatures studied include variations in shape, colour, texture, hilar details,surface scan characteristics and seed coat anatomy. Anatomically, the testahas been found to be of greatest value in determining taxonomic relationships.Some seed characters were found to be very distinct at the generic level, suchas the presence of two rows of the palisade-like cells of the seed wing (oneupper and one lower) which could be considered as taxonomic marker for thetwo Pergularia species. In addition, the presence of mounds on the upperconcave side of the seed coat is recorded only in two Asclepias species andSolenostemma arghel; with large, tubular, lignified, pitted cells in twoAsclepias species, and small, rectangular, radially elongated in Solenostemmaarghel.

English

Comparative studies on the morphology and anatomy of the three species of&nbsp;Cucurbita L. (C. moschata, C. maxima and C. pepo)&nbsp;in Nigeria were carried out. The morphological features of significance include variations in the number of tendrils, fruit size, shape, nature of fruit stalk, leaf shape and flower colour. Seed-coat anatomy revealed four distinct zones, which varied in thickness and tissue layers.&nbsp; Similarities were observed in the distribution, differentiation and number of layers of cells and tissues in the leaf, petiole and stem sections. There were, however, variations in number of bicollateral vascular bundles in their petiole. While the number is 10 in&nbsp;C.&nbsp;moschata,&nbsp;14 in&nbsp;C.&nbsp; pepo,&nbsp;it is 16 in&nbsp;C. maxima.&nbsp; Parietal placentation and 15 anther-lobes are reported for these species for the first time. The usefulness of these parameters in the taxonomic delimitation of these species is discussed. &nbsp; Key words:&nbsp;Cucurbita,&nbsp;morpho-anatomy, placentation, seed-coat, taxonomy, vascular bundles.

Structure and development of the ovule and seed in Aristolochiaceae, with particular reference to Saruma

All members of Aristolochiaceae have anatropous, bitegmic, crassinucellate ovules, which are endostomic except in Saruma and Asarum arifolium where ovules are amphistomic. The outer integument is two cell-layered and the inner integument is three cell-layered. The chalazal megaspore is the functional one. All these conditions appear to be plesiomorphic for the order Piperales, which consists of five families, Aristolochiaceae, Hydnoraceae, Lactoridaceae, Piperaceae and Saururaceae. The embryo sac in Aristolochiaceae is eight-nucleate and corresponds to the Polygonum type; a hypostase is frequently present in this family. The seed coat of Aristolochia s.l., Asarum, Saruma and some Thottea species consists primarily of a two cell-layered testa, and a three cell-layered tegmen. In some species the cells of the outer epidermis become radially elongated, forming reticulate wall thickenings. Cells of the inner layer of the testa have crystals and thickened inner walls. The three layers of the tegmen are tangentially elongated, and become cross fibres at maturity, as fibres of the outer and inner layers are parallel to the seed axis, whereas those of the middle layer are perpendicular to it. This type of seed coat anatomy is synapomorphic for Aristolochiaceae. In addition, the gross morphology of the seed and elaiosome histology are remarkably similar in Asarum and Saruma, thus supporting a sister-group relationship between them. Embryological and seed characters do not supply any synapomorphy that support a close relationship between Aristolochiaceae, Hydnoraceae and Lactoridaceae. Instead, some seed features such as the absence of seed appendages and the collapsed cells of endotesta may indicate a close relationship of Lactoris with Piperaceae plus Saururaceae, although this is the subject of further analysis.

Seed-coat structure and anatomy of some Nigerian pulses

Here we report the seed morphology and anatomy of some Nigerian pulses, an investigation that revealed a wide diversity of characteristics in a small collection of seeds. Although these genera share common features, their anatomical differences make it possible to generate a key for identification and classification. Sizes ranged from 5 to 7 x 5 x 3 mm forCajanus cajan up to 25 to 30 x 18 x 19 mm forCanavalia ensiformis. Seed colors were monochromatic black/brown to dichromatic eye/mottled (streaked), and surfaces were either smooth-glossy or puckered. Forms varied from ellipsoid or oblong-ellipsoid to spheroid or reniform, and halos (hilar rims) were either complete or incomplete. Lens shapes were spot, linear, broadly linear, or deltoid. The hila were elliptic to linear (or in-between), with sizes ranging from 0.5 to 1.0 mm (Mucuna pruriens) up to 1.5 to 3.0 mm (Phaseolus vulgaris). Their positions could be completely covered, as inP. vulgaris, partially covered and raised above the seed surface (Vigna subterranea), or naked (without any funicular residue) arid level with the surface, as in Gensiformis (Tce1 ). The aril caps were collar-like inLablab purpureus or cushion-like, as inM. pruriens. Palisade cell sizes ranged from 80.7pm inGlycine max to 1733 µm inC. ensiformis (Tce1), and their shapes varied from a uniformly wall-thickened type (T1), to a bulbous-end type (T2), to one with a corrugated structure on the inner wall (T3). Although these anatomical variations exist, they may not warrant demarcation into sub-familiar or generic classifications. However, we do propose that specific and sub-specific alterations are necessary.

Phylogenetics of Dioscoreales based on combined analyses of morphological and molecular data

Relationships of Dioscoreales are examined by combined analysis of three molecular data sets (plastid rbcL, atpB and nuclear 18S rDNA genes) and a morphological data set. The combined analysis corroborates a narrow circumscription of Dioscoreales, which includes Burmanniaceae and Thismiaceae in the order, and also indicates that Nartheciaceae are closely related. Dioscoreales thus comprise three distinct clades: a well-supported ‘core Dioscoreales’ clade (Dioscorea, Trichopus, Avetra, Tacca and Stenomeris), a Burmanniaceae–Thismiaceae clade and Nartheciaceae. The improvement in resolution and high bootstrap percentages found by the total evidence analysis relative to analyses of separate data sets indicates that both morphological and molecular data are crucial in resolving the relationships of Dioscoreales. Combined analysis of morphological and molecular characters is instructive in interpreting the evolution of morphological characters such as microsporogenesis and revealing characters that were previously not regarded as significant in the higher-level systematics of this group, for example stamen and hypanthium morphology. Other morphological synapomorphies in Dioscoreales include tuberous underground parts, glandular hairs, seed coat anatomy, and calcium oxalate crystals. © 2002 The Linnean Society of London, Botanical Journal of the Linnean Society, 138, 123–144.

Seed Coat Anatomy and Its Relationship to Seed Dispersal in Subfamily Lecythidoideae of the Lecythidaceae (The Brazil Nut Family)

The seed coat anatomy of representative species from all 10 Neotropical genera of Lecythidaceae subfamily Lecythidoideae and from the Paleotropical Barringtonia (Lecythidaceae subfamily Planchonioideae) was studied. The seed coat is mainly composed of the testa, which is developed through moderate or intensive multiplication of the outer integument of the ovule. The tegmen, derived from the inner integument of the ovule, is mostly crushed at seed maturity. Barringtonia and Grias, with fruits as diaspores, have an unspecialized exotesta and a poorly differentiated seed coat. In contrast, species of Lecythidoideae, with seeds as diaspores, possess well-differentiated seed coats with diversified protective mechanisms. Examples include: an expanded and lignified exotesta that serves as a water barrier and protects the embryo; an extensive area of tannin cells that provides a chemical defense against pathogens and predators; a thick and sclerotic mesotesta that protects the embryo; and large fibers surrounding and supporting the vascular bundles. In addition, other modifications of the seed coat are probably adaptations for seed dispersal by different dispersal agents. These include the exotestal hairs of Couroupita guianensis, which possibly protect the embryos as they pass through the digestive tracts of peccaries; an extension of the seed coat into a wing in species of Cariniana and Couratari, which facilitate wind dispersal; the papillate exostestal cells of Allantoma lineata, which probably promote dispersal by water; the well-developed arils of species of Corythophora and Lecyt his, probably sought after by animals, which in turn disperse the seeds; and the sarcotesta of Eschweilera ovalifolia, consumed by fish, which in turn disperse the seeds. We conclude that the highly diversified anatomy and morphology of the seed coat of the Lecythidoideae has evolved from relatively homogeneous ovules in response to pathogens and predators as well as to abiotic and biotic dispersal agents.

Studies in the Maloideae (Rosaceae) 1- Chaenomeles Lindley and Cydonia Miller

Macromorphological characters, SEM of seed coat surface criteria, seed coat anatomy and seed proteinelectrophoresis aspects, were used to re-assess the taxonomic relationships between the genera Chaenomeles andCydonia. Characters were analyzed by the NTsys-pc. program package, using the UPGMA clustering method.The dendrograms produced were discused and showed a close relationship between Chaenomeles sinensisKoehne and Cydonia oblonga Miller. The result gives support to the merging of the former taxon in the genusCydonia as presented in Mabberley (1997).