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.

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 ◽  
Leafy Spurge ◽  
Endosperm Development ◽  
Euphorbia Esula

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.

scholarly journals Embryology and cytogenetics of Eupatorium pauciflorum and E. intermedium (Compositae)

1998 ◽  
Vol 21 (4) ◽  
pp. 507-514 ◽  
Author(s):  
Maristela Sanches Bertasso-Borges ◽  
James Robert Coleman
Keyword(s):  
Embryo Sac ◽  
Pollen Grains ◽  
Endosperm Development ◽  
Egg Cell ◽  
Pollen Production ◽  
Polygonum Type ◽  
Total Absence ◽  
Basic Set ◽  
Autonomous Endosperm ◽  
Germinated Pollen

The embryology of Eupatorium pauciflorum indicates diplospory with autonomous endosperm development. The embryo sac is of the polygonum type and the polar nuclei mostly fuse before anthesis. The occurrence of precocious embryo and endosperm development in unopened florets, and the total absence of germinated pollen grains on exposed stigmas, as well as the absence of pollen tubes in the ovules, indicate agamospermy to be obligate and embryo and endosperm development autonomous. The study of microsporogenesis revealed the total absence of pollen production in consequence of microsporocyte degeneration before the onset of meiosis, which resulted in absolute male sterility. E. pauciflorum was demonstrated to be an autotriploid with a basic set of 10 chromosomes, each represented three times. Embryological studies showed E. intermedium to undergo reductive meiosis with tetrad formation during megasporogenesis, followed by monosporic embryo sac development of the polygonum type. The polar nuclei fuse before anthesis. The egg cell invariably attains anthesis still undivided, without precocious embryony. Meiosis of microsporogenesis results in the regular formation of 10 bivalents and the subsequent stages of microsporogenesis are normal. Stigmatic loads indicate the regular occurrence of pollination with viable, functional grains. Karyotypic studies revealed a complement of 20 chromosomes separable into 10 pairs. It is concluded that E. pauciflorum, as represented by the material studied, is apomictic while E. intermedium is sexual.

scholarly journals Reproductive biology of leafy spurge (Euphorbia esula L.): breeding system analysis

2000 ◽  
Vol 77 (11) ◽  
pp. 1684-1688
Author(s):  
Sarena M Selbo ◽  
Jeffrey S Carmichael
Keyword(s):  
North America ◽  
Reproductive Biology ◽  
Breeding System ◽  
Microscopic Examination ◽  
Reproductive Strategies ◽  
System Analysis ◽  
Leafy Spurge ◽  
Euphorbia Esula ◽  
Invasive Weed ◽  
Native Invasive

Leafy spurge (Euphorbia esula L.) represents a non-native, invasive weed that dominates many regions across North America. While many research efforts are aimed at controlling the growth and spread of this plant, relatively little is known about its breeding system. This study provides evidence that leafy spurge is self-compatible, with selfed plants producing roughly half as many seeds as outcrossed plants. Unpollinated flowers failed to set seed and thus preliminary tests for apomixis were negative. However, microscopic examination of pollinated flowers revealed that pollen tubes did not appear to enter ovules in either selfed or outcrossed flowers. Therefore, leafy spurge exhibits structural evidence that suggests pseudogamy may play a role in the reproductive strategies of this invasive weed.

scholarly journals Release of Postsenescent Dormancy in Leafy Spurge (Euphorbia esula) by Chilling

Weed Science ◽  
1988 ◽  
Vol 36 (6) ◽  
pp. 784-786 ◽  
Author(s):  
Stephen J. Harvey ◽  
Robert M. Nowierski
Keyword(s):  
Growth Rate ◽  
North America ◽  
Growth And Development ◽  
Leafy Spurge ◽  
Climatic Conditions ◽  
Euphorbia Esula ◽  
Flower Buds ◽  
Significant Growth ◽  
Number Of Stems

The growth and development of leafy spurge (Euphorbia esulaL. #3EPHES) collected during postsenescent dormancy and grown in the greenhouse was increasingly stimulated by chilling treatments longer than 14 days duration at 0 to 6 C. Production of stems with flower buds, primary flowers, and secondary flowers was greater in plants chilled for 42 days or more. The effects of chilling on total number of stems, number of strictly vegetative stems, or number of stems with vegetative branching were not significant. The height of the tallest stem per pot was influenced by chilling longer than 42 days. Growth rate also increased as a function of chilling duration. Based on our findings, we believe that there is little possibility that any significant growth can occur in the postsenescent period because of the prevailing climatic conditions found in areas of leafy spurge distribution in North America.

Reproductive development in two species of Darwinia Rudge (Myrtaceae)

1969 ◽  
Vol 17 (2) ◽  
pp. 215 ◽  
Author(s):  
N Prakash
Keyword(s):  
Embryo Sac ◽  
Pollen Grains ◽  
Reproductive Development ◽  
Outer Zone ◽  
Mature Embryo ◽  
Globular Embryo ◽  
Primary Endosperm Nucleus ◽  
Oil Glands ◽  
Polygonum Type ◽  
History Of

In Darwinia the floral parts are differentiated in a "calyx-orolla-gynoeciumandroecium" sequence. In individual buds stages of microsporogenesis markedly precede corresponding stages of megasporogenesis. The anther is tetrasporangiate with all sporangia lying in one plane. The secretory tapetum is one- to three-layered within the same microsporangium and a large number of Ubisch bodies are formed. The anthers dehisce by minute lateral pores and an ingenious mechanism helps disperse the twocelled pollen grains. A basal placenta in the single loculus of the ovary bears four ovules in D. micropetala and two in D. fascicularis. In both species, however, only one ovule is functional after fertilization. The fully grown ovules are anatropous, crassinucellar, and bitegmic; the inner integument forms the micropyle. The parietal tissue is most massive at the completion of megasporogenesis but is progressively destroyed later. The embryo sac follows the Polygonum type of developnlent and when mature is five-nucleate, the three antipodals being ephemeral. Following fertilization, the primary endosperm nucleus divides before the zygote. Subsequent nuclear divisions in the endosperm mother cell are synchronous and lead to a free-nuclear endosperm which becomes secondarily cellular, starting from the micropylar end at the time the globular embryo assumes an elongated shape. Embryogeny is irregular and the mature embryo is straight with a massive radicle and a hypocotyl which terminates in two barely recognizable cotyledons. Sometimes the minute cotyledons are borne on a narrow neck-like extension of the hypocotyl. A suspensor is absent. Both integuments are represented in the seed coat and only the outer layer of the outer and the inner layer of the inner integuments, with their thick-walled tanniniferous cells, remain in the fully grown seed. The ovary wall is demarcated into an outer zone containing oil glands surrounded by cells containing a tannin-like substance and an inner zone of spongy parenchyma. In the fruit this spongy zone breaks down completely but the outer zone is retained. The two species of Darwinia, while closely resembling each other in their embryology, differ significantly from other Myrtaceae. However, no taxonomic conclusions are drawn at this stage, pending enquiry into the life history of other members of the tribe Chamaelaucieae.

A Note on the Sugars and Amino Acids of Leafy Spurge, Euphorbia esula

Weeds ◽  
1956 ◽  
Vol 4 (3) ◽  
pp. 275 ◽  
Author(s):  
Duane Le Tourneau
Keyword(s):  
Amino Acids ◽  
Leafy Spurge ◽  
Euphorbia Esula

scholarly journals Polyamines, auxins and organogenesis in leafy spurge (Euphorbia esula L.)

1997 ◽  
Vol 151 (5) ◽  
pp. 603-609 ◽  
Author(s):  
David G. Davis
Keyword(s):  
Leafy Spurge ◽  
Euphorbia Esula

Embryological studies in the compositae, I. Sporogenesis, Gametogenesis, and Embryogeny in Cotula australis (Less.) Hook. F

1962 ◽  
Vol 10 (1) ◽  
pp. 1 ◽  
Author(s):  
GL Davis
Keyword(s):  
Mother Cell ◽  
Megaspore Mother Cell ◽  
Embryo Sac ◽  
Subsequent Development ◽  
Pollen Grains ◽  
Archesporial Cell ◽  
Polygonum Type ◽  
Wall Formation ◽  
Chalazal Megaspore

Cotula australis has a discoid heterogamous capitulum in which the outermost three whorls of florets are female and naked. The bisexual disk florets are fully fertile and have a four-lobed corolla with four shortly epipetalous stamens. The anthers contain only two microsporangia. Wall formation and microsporogenesis are described and the pollen grains are shed at the three-celled condition. The ovule is teguinucellate and the hypodermal archesporial cell develops directly as the megaspore mother cell. Megasporogenesis is normal and the monosporio embryo sac develops from the chalazal megaspore. Breakdown of the nucellar epidermis takes place when the embryo sac is binucleate and its subsequent development follows the Polygonum type. The synergids extend deeply into the micropyle and one persists until late in embryogeny as a haustorium. The development of the embryo is of the Asterad type, and the endosperm is cellular. C. coronopifolia agrees with C. australis in the presence of only two microsporangia in each anther and the development of a synergid haustorium.

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