Embryology of the dioecious Australian endemic Lomandra longifolia (Lomandraceae)

2008 ◽  
Vol 56 (8) ◽  
pp. 651 ◽  
Author(s):  
Nabil M. Ahmad ◽  
Peter M. Martin ◽  
John M. Vella
Keyword(s):  
Middle Layer ◽  
Endosperm Development ◽  
Anther Wall ◽  
Polygonum Type ◽  
Cell Functions ◽  
Mature Ovule ◽  
Cell Layers ◽  
Nucellar Tissue ◽  
Successive Cytokinesis ◽  
Dermal Cells

Microsporogenesis, embryogeny and endosperm development of Lomandra longifolia Labill. are described in detail. The formation of the anther wall is the basic type composed of four cell layers, namely an epidermis, an endothecium, one middle layer and a tapetum. The tapetum layer has glandular, uninucleate cells. Successive cytokinesis follows meiosis, subsequently forming a tetrahedral tetrad of microspores. The ovule in each carpel is hemitropous, crassinucellate and bitegmic, with the micropyle formed by the inner integument. The archesporial cell divides periclinally to form the primary parietal and primary sporogenous cells. The sporogenous cell functions as the megaspore mother cell, whereas the parietal cell divides to give rise to two parietal layers. The mature megagametophyte, which has enlarged synergids and antipodals, is of the Polygonum type, with the normal complement of seven cells and eight nuclei. Nucellar tissue in the mature ovule consists of enlarged dermal cells and irregular subdermal cells surrounding a central strand of markedly smaller cells. Endosperm development is of the nuclear type. Embryo development is of the Graminad type, characterised by oblique zygotic and early pro-embryonic divisions.

Sporogenesis, Gametogenesis, and embryogeny of Wahlenbergia bicolor N. Lothian

1963 ◽  
Vol 11 (2) ◽  
pp. 152 ◽  
Author(s):  
G Want
Keyword(s):  
Mother Cell ◽  
Embryo Sac ◽  
Pollen Grains ◽  
Type A ◽  
Middle Layer ◽  
Anther Wall ◽  
Suspected Case ◽  
Polygonum Type ◽  
Chalazal Megaspore ◽  
Coastal Species

In Wahlenbergia bicolor, the anther wall is composed of four layers: epidermis, endothecium, middle layer, and tapetum. Wall formation and microsporogenesis are described, and the pollen grains are shed at the two-celled condition. The ovules are tenuinucellate, with a hypodermal archesporial cell which develops directly as the megaspore mother cell. Megasporogenesis is normal, and a monosporic eight-nucleate embryo sac of the most common Polygonum type develops from the chalazal megaspore. The antipodals degenerate before fertilization. The development of the embryo is of the solanad type. A suspected case of polyembryony was observed. The endosperm is cellular from its inception, and so conforms to the Codonopsis type. A micropylar and a chalazal haustoriurn, both consisting of two uninucleate cells, are formed from the endosperm. Comparative studies were made with a known but as yet undescribed coastal species of Wahlenbergia, and no differences were found.

scholarly journals Development of the Middle Layer in the Anther of Arabidopsis

2021 ◽  
Vol 12 ◽  
Author(s):  
Jing-Shi Xue ◽  
Chi Yao ◽  
Qin-Lin Xu ◽  
Chang-Xu Sui ◽  
Xin-Lei Jia ◽  
...  
Keyword(s):  
Cell Division ◽  
Fluorescent Proteins ◽  
Middle Layer ◽  
Live Imaging ◽  
Anther Development ◽  
Anther Wall ◽  
Fundamental Information ◽  
Stage 4 ◽  
Cell Layers ◽  
Staining Methods

The middle layer is an essential cell layer of the anther wall located between the endothecium and tapetum in Arabidopsis. Based on sectioning, the middle layer was found to be degraded at stage 7, which led to the separation of the tapetum from the anther wall. Here, we established techniques for live imaging of the anther. We created a marker line with fluorescent proteins expressed in all anther layers to study anther development. Several staining methods were used in the intact anthers to study anther cell morphology. We clarified the initiation, development, and degradation of the middle layer in Arabidopsis. This layer is initiated from both the inner and outer secondary parietal cells at stage 4, stopped cell division at stage 6, and finally degraded at stage 11. The neighboring cell layers, the epidermis, and endothecium continued cell division until stage 10, which led to a thin middle layer. The degradation of the tapetum cell wall at stage 7 lead to its isolation from the anther wall. This work presents fundamental information on the development of the middle layer, which facilitates the further investigation of anther development and plant fertility. These live imaging methods could be useful in future studies.

Embryology and Reproductive Ecology of the Darling Lily, Crinum flaccidum Herbert

1990 ◽  
Vol 38 (5) ◽  
pp. 433 ◽  
Author(s):  
G Howell ◽  
N Prakash
Keyword(s):  
Pollen Grains ◽  
Mature Embryo ◽  
Microspore Mother Cell ◽  
Polygonum Type ◽  
Binucleate Cells ◽  
Cell Layers ◽  
Nectar Sugar ◽  
Endosperm Formation ◽  
Successive Cytokinesis ◽  
Seed Coats

In Crinum flaccidum the anthers are versatile and tetrasporangiate with a secretory tapetum of binucleate cells. Successive cytokinesis in microspore mother cell results in isobilateral and decussate microspore tetrads. The mature pollen grains are single, spheroidal, disulculate, echinate and 2-celled. In the mature anthers, fibrous thickenings develop not only in the endothecium but also in two or three middle cell layers and the connective tissue before latrorse dehiscence. A lobed tissue in each of the three locules of the ovary serves ovular and placental functions. Each extension of the 5-7 paired lobes represents an ategmic ovule. The development of the female gametophyte conforms to the Polygonum type. Usually only one gametophyte is present in each lobe but occasionally several may occur. Bulb growth is monopodial with normally three umbels produced per plant, each carrying an average of 10 flowers, only two or three of which are open at any one time. Nectar sugar concentration was measured at 14.2% (w/w), of which 44.8% of solids was sucrose and 3.9% either glucose or fructose. The protandrous flowers are phalenophilous, pollinated by sphingid moths. The endosperm formation is of the nuclear type. In the absence of seed coats and the nucellus at maturity, the outer layers of the endosperm become corky following the activity of a phellogen. Embryogeny appears to be of the Asterad type. The mature embryo is straight and chlorophyllous. The large (5.3 g) seeds are 89% water and show no dormancy, germinating without an external supply of water, sometimes while still on the parent plant.

Gametogenesis and seed development in Hereroa hesperantha (Dtr.) Dtr. et Schwant (Aizoaceae).

1967 ◽  
Vol 15 (3) ◽  
pp. 425 ◽  
Author(s):  
N Prakash
Keyword(s):  
Female Gametophyte ◽  
Mature Seed ◽  
Anther Wall ◽  
Polygonum Type ◽  
Multinucleate Cells ◽  
Cell Functions ◽  
Innermost Layer ◽  
Tapetal Cells ◽  
Sporadic Cases ◽  
Mother Cells

Hereroa hesperantha belongs to the embryologically little known group of mesembryanthemums. The anther wall is four-layered, the innermost layer constituting the secretory tapetum with multinucleate cells. Prominent Ubisch granules dot the inner tangential and radial walls of the tapetal cells. Cytokinesis in the microspore mother cells is simultaneous, and either tetrahedral or decussate tetrads are formed. The mature pollen is three-celled. The ovules are anacampylotropous, bitegminal, crassinucellar, and non-arillate. The need for employing a uniform terminology for ovular curvature in the Aizoaceae is stressed in view of the existing confusion. The ovules are borne on parietal placentae each of which bears an obturator. The archesporium is one- to many-celled, but only one cell functions. Sporadic cases of double megaspore tetrads and two-nucleate dyad cells were observed. The development of the female gametophyte conforms to the Polygonum type. The synergids and antipedal cells are short-lived. The endosperm is of the Nuclear type and produces a weakly haustorial chalazal caecum. Perisperm takes over the function of endosperm in the mature seed. The embryogeny corresponds to the Solanad type. There is a massive suspensor with some multinucleate cells. The mature seed coat resembles closely that of the Cactaceae and comprises the outer layer of the outer and inner layer of the inner integument, both of which become greatly enlarged and tanniniferous. In features like the presence of staminodes and inferior ovary and the absence of aril, Hereroa differs from other Aizoaceae.

scholarly journals Improvement of Selected Induction Culture Media on Callus Induction in Anther Culture of Anthurium and a Histological Study on its Callus Formation

2012 ◽  
Vol 12 (2) ◽  
pp. 93 ◽  
Author(s):  
Budi Winarto ◽  
Nurhayati Ansori Mattjik ◽  
Agus Purwito ◽  
Budi Marwoto
Keyword(s):  
Anther Culture ◽  
Callus Induction ◽  
Culture Media ◽  
Callus Formation ◽  
Histological Study ◽  
Block Design ◽  
Middle Layer ◽  
Shoot Formation ◽  
Anther Wall ◽  
Randomized Complete Block Design

Improvement of selected induction culture media on callus induction in anther culture of anthurium and a histologicalstudy on its callus formation were studied at the tissue culture laboratory of the Indonesian Ornamental CropsResearch Institute from February to October 2008. The objectives of the study were to optimize selected media forcallus formation, reveal cell origin of callus derived from anther culture and shoot formation process. Selectedmedia improved in the study were 1) MMS-TBN containing 0,5 mg/l TDZ, 1,0 mg/l BAP and 0,01 mg/l NAA (Winartomedium, WM) and 2) MMS III supplemented with 1,5 mg/l TDZ, 0,75 mg/l BAP and 0,02 mg/l NAA (Winarto andRachmawati medium, WRM). Improvement treatments were carried out by omission and application of 2,4-D in 0.5mg/l and reduction of medium strength of full, half, quarter, one eighth, one sixteenth, and zero strength. Afactorial experiment was arranged using a randomized complete block design with four replications. Results ofthis study indicated that the highest callus induction was clearly established in WRM. The medium stimulatedpotential growth of anther (PGA) up to 81% with 49% of percentage of anther regeneration (PAR) and 2.7 number ofcallus formed per replication (NCF). Significant improvement in callus formation was also recorded by reduction ofmedium strength of WRM to one eighth compared to others. The reduction induced PGA up to 58% with 29% of PARand 1.8 NCF. From histological studies it was well recognized that regenerated callus on half anthers cultured wasoriginated from middle layer cells of anther wall. The morphogenic response of anther wall cells caused primarilyon no androgenesis effect in microspore cells.

scholarly journals Dynamics of Polysaccharides and Neutral Lipids during Anther Development in Castor (Ricinus communis)

2015 ◽  
Vol 140 (4) ◽  
pp. 356-361 ◽  
Author(s):  
Dongmei Wei ◽  
Huimin Xu ◽  
Ruili Li
Keyword(s):  
Neutral Lipids ◽  
Ricinus Communis ◽  
Starch Content ◽  
Single Layer ◽  
Pollen Grains ◽  
Middle Layer ◽  
Anther Development ◽  
Anther Wall ◽  
Starch Grains ◽  
Tapetal Cells

Anthers contain starch and neutral lipids, which have key roles in microspore ontogeny and gametophyte development. In this study, we observed the dynamic changes in starch and neutral lipids in the anther developmental processes of castor (Ricinus communis) by cytochemical methods. Starch grains and neutral lipids presented a regular dynamic distribution during anther development. In young anthers, some neutral lipids accumulated in sporogenous cells, whereas neutral lipids disappeared with microspore growth. At the late microspore stage, starch grains began to accumulate in microspores, and the starch content of bicellular pollen significantly increased after microspore mitosis. At anthesis, starch grains and neutral lipids accumulated in the mature pollen grains. Visible changes occurred in anther wall cells. The epidermis, middle layer, and tapetum were degenerated, and only a single layer of endothecium remained at anthesis. The dynamic variation of starch grains and neutral lipids in tapetal cells was consistent with the changes in microspores and pollen during anther development. All these findings demonstrated that tapetal cells directly interacted with the developing gametophytes. The tapetal cells play an important role in supplying nutritional substances for microspore absorption. Moreover, the endothecium protects the pollen and contributes to anther dehiscence. The results of this study provide a foundation for the further research on sexual reproduction in angiosperms.

The floral morphology and embryology of Themeda australis (R. Br.) Stapf

1964 ◽  
Vol 12 (2) ◽  
pp. 157 ◽  
Author(s):  
PS Woodland
Keyword(s):  
Embryo Sac ◽  
Pollen Grains ◽  
Low Fertility ◽  
Linear Tetrad ◽  
Polygonum Type ◽  
Morphological Variations ◽  
Endosperm Formation ◽  
Secretory Type ◽  
Successive Cytokinesis ◽  
Mother Cells

A comparative study was carried out between diploid and tetraploid races of Themeda australis from Armidale and Cobar, respectively. Some morphological variations occur in both populations, but sporogenesis and gametogenesis are identical. The anther is tetrasporangiate and the development of its four-layered wall is described. The tapetum is of the secretory type and its cells become binucleate at the initiation of meiosis in the adjacent microspore mother cells which undergo successive cytokinesis. Microspore tetrads are usually isobilateral and the pollen grains are three-celled at dehiscence, which takes place by lateral longitudinal slits. The ovule is of a modified anatropous form and bitegmic, the broad micropyle being formed of both integuments. The single hypodermal archesporial cell develops directly into the megaspore mother cell and the nucellar epidermis undergoes periclinal and anticlinal divisions to form a conspicuous epistase. The chalaza1 megaspore of the linear tetrad gives rise to a Polygonum-type embryo sac. Material from the Armidale population showed one embryo sac per ovule, but two to five embryo sacs were present in that from Cobar. Embryogeny is typically graminaceous and endosperm formation is at first free-nuclear, later becoming cellular. Polyembryony follows fertilization of several embryo sacs within the same ovule. The reasons for low fertility of T. australis and poor germination of seeds are discussed.

Embryology of Isotoma petraea

1970 ◽  
Vol 18 (2) ◽  
pp. 213 ◽  
Author(s):  
IC Beltran
Keyword(s):  
Mother Cell ◽  
Embryo Sac ◽  
Endosperm Development ◽  
Ovule Development ◽  
Polygonum Type ◽  
Development Patterns ◽  
Embryo Formation ◽  
Ring Bivalents ◽  
Form Ring ◽  
Embryo Sac Formation

Ovule development, embryo sac formation, and embryogeny of I. Petraea are described. The ovules are anatropous, unitegmic, and tenuinucellar. Meiosis in the megaspore mother cell is regular and the chromosomes with terminalized chiasmata form ring bivalents at metaphase 1. The Polygonum type embryo sac, Scutellaria type endosperm development, and Solanad embryo formation correspond with development patterns in other members of the Lobeliaceae.

Ovule, embryo sac, embryo, and endosperm development in leafy spurge (Euphorbia esula)

1999 ◽  
Vol 77 (4) ◽  
pp. 599-610 ◽  
Author(s):  
Jeffrey S Carmichael ◽  
Sarena M Selbo
Keyword(s):  
Embryo Sac ◽  
Placental Tissue ◽  
Leafy Spurge ◽  
Endosperm Development ◽  
Protein Bodies ◽  
Euphorbia Esula ◽  
Invasive Weed ◽  
Polygonum Type ◽  
Nutrient Reserve ◽  
Endosperm Formation

Leafy spurge (Euphorbia esula L.) is a noxious, invasive weed that dominates many agriculturally important regions. While many research efforts are currently aimed at controlling the spread of this plant, relatively little is known about its sexual reproductive biology, especially from a structural perspective. This report describes key features of ovule development, embryogenesis, and endosperm formation in leafy spurge. Ovules are anatropous, bitegmic, and form a zigzag micropyle. A distinct elaisome (caruncle) and hypostase are formed as ovules mature. Obturators are present and are derived from placental tissue. The embryo sac conforms to the Polygonum type. A single embryo is formed in each seed and stores nutrients primarily as globoid protein bodies. Endosperm is persistent and also contains protein bodies as its primary nutrient reserve. Preliminary structural evidence is presented that indicates the potential for apomixis.Key words: leafy spurge, Euphorbiaceae, Euphorbia, ovule, endosperm, embryo.

scholarly journals On the Embryology of Two Species of Genus Lepidium (Brassicaceae)

HortScience ◽  
2018 ◽  
Vol 53 (4) ◽  
pp. 582-588
Author(s):  
Elina Yankova-Tsvetkova ◽  
Ivanka B. Semerdjieva ◽  
Rozalia Nikolova ◽  
Valtcho D. Zheljazkov
Keyword(s):  
Embryo Sac ◽  
Pollen Grains ◽  
Middle Layer ◽  
Reproductive Capacity ◽  
Marginal Lands ◽  
Potential Development ◽  
The Family ◽  
Mature Ovule ◽  
The Stability ◽  
Cultivation Techniques

Some species of genus Lepidium of the family Brassicaceae are ruderal plants, and they can grow well on less fertile soils and may have potential as oilseed crops for marginal lands. To develop cultivation techniques for wild species, the reproductive capacity of the species needs to be revealed. The objective of this work was embryological study of two Lepidium species (L. campestre and L. ruderale). As a result of the study, the main features of male and female generative spheres were established. Male generative sphere: The anther is tetrasporangiate and its wall, the development of which follows the monocotyledonous-type, consists of epidermis, endothecium, one middle layer, and glandular tapetum. Predominantly, tetrahedral microspore tetrads form after simultaneous type of microsporogenesis. The mature pollen grains are two-celled. Female generative sphere: The mature ovule is ana-amphytropous, crassinucellate, and bitegmic with unicellular archesporium that functions as a megaspore mother cell without cutting off of parietal cells. The development of the embryo sac follows the polygonum-type development. The embryo and endosperm develop after the onagrad-type embryogenesis. The established peculiarities of the reproductive biology characterize the studied species as sexually reproducing taxa that guarantee the stability of size of their populations. This is important for the conservation of these species as part of the Bulgarian flora biodiversity given their status of valuable medicinal plants. The data obtained will contribute to the knowledge of the embryological characteristic of genus Lepidium. The results contribute to the understanding of Lepidium biology and potential development of Lepidium species as oilseed cash crops for marginal lands.

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