Summary
Electron microscope studies have been conducted on the parthenogenesis induced by in vitro culture of unfertilized ovules of sunflower (Helianthus annuus). In comparison with the state of the egg prior to inoculation, some eggs 5 days after culture show striking ultrastructural changes, which include, among others, nuclear migration, an increase in the number and activity of the organelles, a loss of polarity and wall formation at the chalazal end of the cell. Most of these changes are similar to those that occur normally in the zygote, indicating that parthenogenic development has been triggered in these eggs. Such eggs have been termed activated and are presumed to be capable of undergoing parthenogenesis. The parthenogenic proembryos which result share some features in common with zygotic proembryos. In addition, some parthenogenic proembryos exhibit unique properties not found in zygotic proembryos. These include embryos that consist of two parts differing markedly in density, an inversion of polarity, the frequent occurrence of autophagic vacuoles, the thickening of cell walls, a centripetal growth mode of wall formation, the appearance of an incomplete cell wall, free nuclear division, amitosis and degeneration. We believe that these ultrastructural peculiarities are the effects of in vitro culture.
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References
Dunwell JM, Sunderland N (1974) Pollen ultrastructure in anther cultures of Nicotiana tabacum. II. Changes associated with embryogenesis. J Exp Bot 25:263–373
He CP, Yang HY (1987) Picloram as an exogenous hormone promotes embryoid differentiation in rice ovary culture. Acta Biol Exp Sin 20:283–291
Huang B (1986) Ultrastructural aspects of pollen embryogenesis in Hordeum, Triticum and Paeonia. In: Hu H, Yang HY (eds) Haploids of higher plants in vitro. China Academic Publisher, Beijing/Springer, Berlin Heidelberg New York, pp 91–117
Kimber G, Riley R (1963) Haploid angiosperms. Bot Rev 29:480–531
Magoon M, Khanna KR (1963) Haploids. Caryologia 16:191–235
Mogensen HL (1973) Some histochemical, ultrastructural and nutritional aspects of the ovule of Quercus gambelii. Am J Bot 60:48–54
Natesh S, Rau MA (1984) The embryo. In: Johri BM (ed) Embryology of angiosperms. Springer, Berlin Heidelberg New York, pp 377–443
Newcomb W (1973a) The development of the embryo sac of sunflower Helianthus annuus before fertilization. Can J Bot 51:863–878
Newcomb W (1973b) The development of the embryo sac of sunflower Helianthus annuus after fertilization. Can J Bot 51:879–890
Rashid A, Siddiqui AW, Reinert J (1982) Subcellular aspects of origin and structure of pollen embryos of Nicotiana. Protoplasma 113:202–208
Schilde-Rentschler L (1977) Role of the cell wall in the ability of tobacco protoplasts to form callus. Planta 135:177–181
Schulz R, Jensen WA (1969) Capsella embryogenesis: the suspensor and the basal cell. Protoplasma 67:139–163
Sunderland N, Dunwell JM (1977) Anther and pollen culture. In: Street HE (ed) Plant tissue and cell culture. Blackwell, Oxford, pp 223–264
Tian HQ, Yang HY (1984) Morphogenetic aspects of gynogenetic embryoid and callus in ovary culture of Oryza sativa L. Acta Bot Sin 26:272–375
Villiers TA (1967) Cytolysomes in long-dormant plant embryo cells. Nature 214:1356–1357
Wei CY, Yang HY (1986) Histochemical studies on in vitro parthenogenesis in Helianthus annuus L. Acta Bot Sin 28:117–122
Yan H, Yang HY (1989) An ultrastructural study on the in vitro parthenogenesis in sunflower. Acta Bot Sin 31:1–6
Yan H, Wu Y, Chen XM, Wei ZY, Zhou C, Yang HY (1985) Microscopical observation on the embryoid formation in cultured unfertilized ovules of Helianthus annuus L. Acta Bot Sin 27:13–18
Yan H, Dong J, Zhou C, Yang HY (1987) Regulation of in vitro parthenogenesis and somatic proliferation in sunflower by several factors. Acta Bot Sin 29:580–587
Yan H, Zhou C, Yang H (1988) Experimental studies on several factors affecting unfertilized ovule culture in sunflower. J Wuhan Bot Res 6:319–326
Yan H, Yang HY, Jensen WA (1989) Ultrastructure of developing embryo sac of sunflower (Helianthus annuus) before and after fertilization. Protoplasma (in press)
Yang HY, Zhou C (1982) In vitro induction of haploid plants from unpollinated ovary and ovules. Theor Appl Genet 63:97–104
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Yan, H., Yang, HY. & Jensen, W.A. An electron microscope study on in vitro parthenogenesis in sunflower. Sexual Plant Reprod 2, 154–166 (1989). https://doi.org/10.1007/BF00192762
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DOI: https://doi.org/10.1007/BF00192762