Development of the Embryo Sac in Amitostigma kinoshitae (Makino) Schltr. (Orchidaceae)

Abe, Kiyohiko

doi:10.1093/oxfordjournals.aob.a085367

Cited by 8 publications

(5 citation statements)

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“…According to Yeung & Law (), there is a tendency for orchids to have a reduced number of nuclei in the embryo sac. Abe () commented that a seven‐celled, eight‐nucleate embryo sac is in fact uncommon in Orchidaceae. It is not possible to generalize about the number of nuclei in the embryo sacs of orchids based on the few reports available and, as stated by Yeung & Law (), past findings of orchid embryo sac contents may need to be re‐evaluated as observations based on paraffin or plastic sections alone may be imprecise.…”

Section: Discussionmentioning

confidence: 99%

The embryo sac ofVanilla imperialis(Orchidaceae) is six-nucleate, and double fertilization and formation of endosperm are not observed

2014

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Double fertilization and subsequent endosperm formation are two of the most important synapomorphies of the angiosperms. Endosperm is generally lacking in Orchidaceae, but Swamy reported the formation of up to ten endosperm nuclei in Vanilla planifolia in 1947. The observation was documented only by line drawings and has not been confirmed; however, assumptions about endosperm formation occurring in Orchidaceae are primarily founded on Swamy's study. The current study provides the first detailed description of embryo sac formation and early embryogeny in Vanilla since Swamy, and is the first using modern imaging techniques. Flowers of Vanilla imperialis were artificially pollinated at 1-week intervals and the resulting fruits were fixed, embedded and sectioned for light microscopy of embryo sac formation, fertilization and early development of the embryo. Three-dimensional reconstructions of embryo sacs were obtained using confocal laser scanning microscopy on fixed ovules. The mature embryo sac contains only six nuclei as a result of the arrested development of the chalazal nuclei prior to the formation of three antipodals and a polar nucleus. Fertilization was observed 7 weeks after pollination, but double fertilization and the formation of endosperm did not occur.

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Section: Discussionmentioning

confidence: 99%

The embryo sac ofVanilla imperialis(Orchidaceae) is six-nucleate, and double fertilization and formation of endosperm are not observed

2014

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“…Even though the orchid ovules are usually bitegmic, the micropyle is often organized by the inner integument alone. This feature is noted in a majority of orchids, as reported in Amitostigma kinishitae (Abe 1977), Herminium monorchis (Fredrikson 1990), Microstylis wallichii (Sood and Rao 1986), and Neuwiedia veratrifolia (Gurudeva 2019). Histologically, the inner integument becomes multilayered, forming a prominent extension at the micropyle.…”

Section: The Roles Of the Integumentsmentioning

confidence: 60%

The orchid seed coat: a developmental and functional perspective

Lee,

Yeung

2023

Bot Stud

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Orchid seeds are 'dust-like.' The seed coat is usually thin, with only one to a few cell layers. It originates from the integuments formed during ovule development. In orchids, the outer integument is primarily responsible for forming a mature seed coat. The inner integument usually fails to develop after fertilization, becomes compressed, and collapses over the expanding embryo. Hence, the seed coat is formed from the funiculus, chalaza, and outer integumentary cells. The outermost layer of the seed coat, the testa, is lignified, usually at the radial and inner tangential walls. The subepidermal thin-walled layer(s), the tegmen, subsequently cold, resulting in seeds having only a single layer of seed coat cells. In some species, cells of the inner integument remain alive with the ability to synthesize and accumulate lipidic and or phenolic compounds in their walls covering the embryo. This cover is called the 'carapace,' a protective shield contributing to the embryo's added protection. A developmental and functional perspective of the integuments and seed coat during seed development and germination is presented in this review.

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“…This reduction is especially evident in the chalaza) end of the female gametophyte, which may experience the suppression of one or more mitotic divisions andjor the degeneration of nuclei at that portion of the developing gametophyte (Abe, 1972b;Vij and Sharma, 1986). This trend towards a free nuclear condition of the antipodals seems to be much more prevalent in the bisporic than the monosporic mode (Abe, 1977). This trend towards a free nuclear condition of the antipodals seems to be much more prevalent in the bisporic than the monosporic mode (Abe, 1977).…”

Section: The Striking Phenomenonmentioning

confidence: 91%

“…In the genus Cypripedium fiveto seven-nucleate embryo sacs may be observed depending on the stage at which the division is inhibited (Vij and Sharma, 1986). Abe (1977) commented that the usual pattern of the sevencelled, eight-nucleated embryo sac occurs rather rarely in the orchid family. During the last division of the two chalaza!…”

Section: Megagametogenesismentioning

confidence: 99%

“…In addition, the 'antipodal apparatus' in orchids is reduced, both in terms of the number of its components and in a shift from cellular to nuclear organization (Savina, 1974). Among about 20 species in which bisporic development is characteristic, only two species, Cypripedium insigne (Poddubnaya-Arnoldi, 1960 and Pogonia japonica (Abe, 1968a) possess embryo sacs with cellular antipodals (Abe, 1977). Among about 20 species in which bisporic development is characteristic, only two species, Cypripedium insigne (Poddubnaya-Arnoldi, 1960 and Pogonia japonica (Abe, 1968a) possess embryo sacs with cellular antipodals (Abe, 1977).…”

Section: The Striking Phenomenonmentioning

confidence: 99%

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Orchid Biology

1997

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Development of the Embryo Sac in Amitostigma kinoshitae (Makino) Schltr. (Orchidaceae)

Cited by 8 publications

References 0 publications

The embryo sac ofVanilla imperialis(Orchidaceae) is six-nucleate, and double fertilization and formation of endosperm are not observed

The embryo sac ofVanilla imperialis(Orchidaceae) is six-nucleate, and double fertilization and formation of endosperm are not observed

The orchid seed coat: a developmental and functional perspective

Orchid Biology

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