Seed development in Chondrilla juncea L

A study of material from unstressed plants of Chondrilla juncea L. revealed a genetically based sterility in 3-4% of the achenes. Embryogeny is of the Asterad type but the basal cell cb divides horizontally before the vertical division in ca. Polyembryony occurred but seems rare; probably only one embryo in each ovule reaches maturity. The endosperm was nuclear at first, becoming cellular after a number of free mitoses. The outer layers persist in the seed. The uniseriate endothelium develops a persistent cuticle on its inner face, which becomes closely appressed to the remaining endosperm layer as the endothelium degenerates. Endosperm formation was erratic and independent of embryogeny. Because of the presence of aborted embryos associated with a well-developed endosperm, it is suggested that the degeneration is the result either of later formation of the endosperm or of unusually early cutinization of the endothelium.

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The Rab Geranylgeranyl Transferase Beta Subunit Is Essential for Embryo and Seed Development in Arabidopsis thaliana

International Journal of Molecular Sciences ◽

10.3390/ijms22157907 ◽

2021 ◽

Vol 22 (15) ◽

pp. 7907

Author(s):

Joanna Rojek ◽

Matthew R. Tucker ◽

Michał Rychłowski ◽

Julita Nowakowska ◽

Małgorzata Gutkowska

Keyword(s):

Seed Development ◽

Auxin Transport ◽

Rab Proteins ◽

Vesicular Traffic ◽

Polar Localization ◽

Reproductive Structures ◽

Autonomous Endosperm ◽

Endosperm Formation ◽

Geranylgeranyl Transferase ◽

Unfertilized Ovules

Auxin is a key regulator of plant development affecting the formation and maturation of reproductive structures. The apoplastic route of auxin transport engages influx and efflux facilitators from the PIN, AUX and ABCB families. The polar localization of these proteins and constant recycling from the plasma membrane to endosomes is dependent on Rab-mediated vesicular traffic. Rab proteins are anchored to membranes via posttranslational addition of two geranylgeranyl moieties by the Rab Geranylgeranyl Transferase enzyme (RGT), which consists of RGTA, RGTB and REP subunits. Here, we present data showing that seed development in the rgtb1 mutant, with decreased vesicular transport capacity, is disturbed. Both pre- and post-fertilization events are affected, leading to a decrease in seed yield. Pollen tube recognition at the stigma and its guidance to the micropyle is compromised and the seed coat forms incorrectly. Excess auxin in the sporophytic tissues of the ovule in the rgtb1 plants leads to an increased tendency of autonomous endosperm formation in unfertilized ovules and influences embryo development in a maternal sporophytic manner. The results show the importance of vesicular traffic for sexual reproduction in flowering plants, and highlight RGTB1 as a key component of sporophytic-filial signaling.

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Apomixis and abnormal anther development in Calotis lappulacea Benth. (Compositae)

Australian Journal of Botany ◽

10.1071/bt9680001 ◽

1968 ◽

Vol 16 (1) ◽

pp. 1 ◽

Cited By ~ 6

Author(s):

GL Davis

Keyword(s):

New South ◽

Embryo Sac ◽

Pollen Grains ◽

Anther Wall ◽

Male Gametes ◽

Globular Stage ◽

South Wales ◽

Vertical Division ◽

Endosperm Formation ◽

Embryo Sac Formation

A comparative study was made of material collected from four localities in New South Wales and Queensland and a number of embryological aberrations were found to be common to all districts. During microsporogenesis, certain tapetal cells not only failed to contribute to the tapetal periplasmodium but, after increasing in size, they separated from the anther wall and resembled one-, two-, or four-nucleate embryo sacs developing among the microspores. In one anther a structure was present which was very similar to a fully differentiated embryo sac. Although the pollen grains of some anthers contained male gametes, most anthers dehisced when the pollen was two-celled and some shrivelled soon after meiosis. Megasporogenesis was followed by the formation of linear tetrads of megaspores, but embryo sac formation was the result of somatic apospory and C. lappulacea appears to be an obligate apomict. The enlarging somatic cell usually invades the nucellar lobe and replaces the megaspores but one or more such celis commonly develop also in the chalaza, and up to eight embryo sacs were found in one ovule. Enlargement of a chalazal embryo sac sometimes resulted in penetration of the ovular epidermis and its invasion of the loculus as a haustorium-like structure. Extrusion of a developing embryo sac through the micropyle was common. Embryogeny is of the Asterad type, but vertical division of the terminal cell ca was delayed until after the basal cell cb had given rise to superposed cells m and ci. Polyembryony was common but only one embryo in each ovule reached maturity. Endosperm formation was independent of embryogeny but unless it was initiated before the globular stage of the embryo, the embryo sac collapsed and the embryo degenerated.

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Genomic imprinting and seed development: endosperm formation with and without sex

Current Opinion in Plant Biology ◽

10.1016/s1369-5266(00)00130-8 ◽

2001 ◽

Vol 4 (1) ◽

pp. 21-27 ◽

Cited By ~ 81

Author(s):

Ueli Grossniklaus ◽

Charles Spillane ◽

Damian R Page ◽

Claudia Köhler

Keyword(s):

Seed Development ◽

Genomic Imprinting ◽

Endosperm Formation

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Natural Variation in the Degree of Autonomous Endosperm Formation Reveals Independence and Constraints of Embryo Growth During Seed Development in Arabidopsis thaliana

Genetics ◽

10.1534/genetics.107.084889 ◽

2008 ◽

Vol 179 (2) ◽

pp. 829-841 ◽

Cited By ~ 16

Author(s):

Alexander Ungru ◽

Moritz K. Nowack ◽

Matthieu Reymond ◽

Reza Shirzadi ◽

Manoj Kumar ◽

...

Keyword(s):

Arabidopsis Thaliana ◽

Seed Development ◽

Natural Variation ◽

Autonomous Endosperm ◽

Endosperm Formation

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Expression of sucrose synthase in the developing endosperm is essential for early seed development in cotton

Functional Plant Biology ◽

10.1071/fp08017 ◽

2008 ◽

Vol 35 (5) ◽

pp. 382 ◽

Cited By ~ 31

Author(s):

Yong-Ling Ruan ◽

Danny J. Llewellyn ◽

Qing Liu ◽

Shou-Min Xu ◽

Li-Min Wu ◽

...

Keyword(s):

Seed Development ◽

Sucrose Synthase ◽

Potential Role ◽

Critical Role ◽

Endosperm Development ◽

Concentration Difference ◽

Stage Embryo ◽

Endosperm Formation ◽

Early Seed Development

Successful seed development requires coordinated interaction of the endosperm and embryo. In most dicotyledonous seeds, the endosperm is crushed and absorbed by the expanding embryo in the later stages of seed development. Little is known about the metabolic interaction between the two filial tissues early in seed development. We examined the potential role of sucrose synthase (Sus) in the endosperm development of cotton. Sus was immunologically localised in the cellularising endosperm, but not in the heart-stage embryo at 10 days after anthesis. The activities of Sus and acid invertase were significantly higher in the endosperm than in the young embryos, which corresponded to a steep concentration difference in hexoses between the endosperm and the embryo. This observation indicates a role for the endosperm in generating hexoses for the development of the two filial tissues. Interestingly, Sus expression and starch deposition were spatially separated in the seeds. Silencing the expression of Sus in the endosperm using an RNAi approach led to the arrest of early seed development. Histochemical analyses revealed a significant reduction in cellulose and callose in the deformed endosperm cells of the Sus-suppressed seed. The data indicate a critical role of Sus in early seed development through regulation of endosperm formation.

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Ultrastructure of Mouse Basal Cell Carcinoma Exhibiting Sebaceous Differentiation

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s1431927600003214 ◽

1980 ◽

Vol 38 ◽

pp. 738-739

Author(s):

Victoria L. Wade ◽

Winslow G. Sheldon ◽

James W. Townsend ◽

William Allaben

Keyword(s):

Basal Cell Carcinoma ◽

Cell Carcinoma ◽

Topical Application ◽

Basal Cell ◽

Sebaceous Gland ◽

Rats And Mice ◽

Mixed Tumors

Sebaceous gland tumors and other tumors exhibiting sebaceous differentiation have been described in humans (1,2,3). Tumors of the sebaceous gland can be induced in rats and mice following topical application of carcinogens (4), but spontaneous mixed tumors of basal cell origin rarely occur in mice.

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