Development and structure of the female gametophyte in Austrobaileya scandens (Austrobaileyaceae)

Tobe, Hiroshi; Kimoto, Yukitoshi; Prakash, N

doi:10.1007/s10265-007-0085-0

Cited by 25 publications

(27 citation statements)

References 21 publications

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“…Although earlier studies indicated that the female gametophyte in Trimenia was Polygonum-type (11,15), our results clearly show that it is monosporic in origin and four-celled and four-nucleate at maturity. This finding is consistent with the many recent reversals of embryological reports that originally claimed that ancient lineages of extant flowering plants have a seven-celled, eight-nucleate (Polygonumtype) embryo sac (12)(13)(14)(19)(20)(21)(22). Indeed, none of the members of the three most deeply divergent clades of extant angiosperms (Amborella, Nymphaeales, and Austrobaileyales) display the common (among angiosperms) Polygonum-type female gametophyte (17).…”

Section: Discussionsupporting

confidence: 77%

“…However, this fact does not necessarily imply that female gametophyte (egg) competition is absent in ovules of these clades. In all but one of the extant families of Austrobaileyales and Nymphaeales, multiple female gametophytes per ovule are commonly or occasionally formed (10)(11)(12)(13)(14)21). This same phenomenon also has been reported in the magnoliid lineage Laur- ales (33) and in Ceratophyllum (34), the sister clade to eudicots.…”

Section: Intrasexual Female Gametophyte Competition Is Common Amongmentioning

confidence: 55%

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Female gamete competition in an ancient angiosperm lineage

Bachelier

Friedman

2011

Proc. Natl. Acad. Sci. U.S.A.

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In Trimenia moorei , an extant member of the ancient angiosperm clade Austrobaileyales, we found a remarkable pattern of female gametophyte (egg-producing structure) development that strikingly resembles that of pollen tubes and their intrasexual competition within the maternal pollen tube transmitting tissues of most flowers. In contrast with most other flowering plants, in Trimenia , multiple female gametophytes are initiated at the base (chalazal end) of each ovule. Female gametophytes grow from their tips and compete over hundreds of micrometers to reach the apex of the nucellus and the site of fertilization. Here, the successful female gametophyte will mate with a pollen tube to produce an embryo and an endosperm. Moreover, the central tissue within the ovules of Trimenia , through which the embryo sacs grow, contains starch and other carbohydrates similar to the pollen tube transmitting tissues in the styles of most flowers. The pattern of female gametophyte development found in Trimenia is rare but by no means unique in angiosperms. Importantly, it seems that multiple female gametophytes are occasionally or frequently initiated in members of other ancient angiosperm lineages. The intensification of pollen tube (male gametophyte) competition and enhanced maternal selection among competing pollen tubes are considered to have been major contributors to the rise of angiosperms. Based on insights from Trimenia , we posit that prefertilization female gametophyte (egg) competition within individual ovules in addition to male gametophyte (sperm) competition and maternal mate choice may have been key features of the earliest angiosperms.

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Section: Discussionsupporting

confidence: 77%

Section: Intrasexual Female Gametophyte Competition Is Common Amongmentioning

confidence: 55%

Female gamete competition in an ancient angiosperm lineage

Bachelier

Friedman

2011

Proc. Natl. Acad. Sci. U.S.A.

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“…-The embryo sac in Nymphaeales and Austrobaileyales is remarkable in being 4 nucleate and 4 celled, so that the endosperm (which is formed by normal double fertilization) is diploid (Williams & Friedman, 2002, 2004Tobe & al., 2007;Friedman & Ryerson, 2009). Thus this embryo sac has only two rounds of mitotic divisions, and not three as in most other angiosperms.…”

Section: Version Of Recordmentioning

confidence: 99%

Ancestral traits and specializations in the flowers of the basal grade of living angiosperms

Endress

Doyle

2015

TAXON

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New morphological and phylogenetic data prompt us to present an updated review of floral morphology and its evolution in the basal ANITA grade of living angiosperms, Chloranthaceae, and Ceratophyllum. Floral phyllotaxis is complex whorled in Nymphaeales and spiral in Amborella and Austrobaileyales. It is unresolved whether phyllotaxis was ancestrally whorled or spiral, but if it was whorled, the whorls were trimerous. The flowers are probably ancestrally bisexual because in most families with unisexual flowers these flowers exhibit rudiments of the opposite sex. Carpels are largely ascidiate and the closure line is short, either transverse or longitudinal. A style is usually absent or, if present, generally short and not plicate. Angiospermy (carpel sealing) is by secretion, rather than postgenital fusion, except in large‐flowered Nymphaeales and in Illicium, correlated with unusual fruits. Carpels with a single, median, pendent ovule are probably plesiomorphic. Chloranth‐ aceae and Ceratophyllaceae have an unsettled phylogenetic position, but in some phylogenetic analyses they form a clade, which may be sister to the remaining mesangiosperms (Magnoliidae, monocots, eudicots). This position is supported by their carpel characters, which are similar to those of the ANITA grade and different from those of most other mesangiosperms.

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“…In Sparattanthelium (Hernandiaceae, Laurales; Kimoto and Tobe 2008), the two-cell-layered nucellar cap is formed early in ovule development, as in Japonolirion. However, a two-cell-layered nucellar cap is not formed in the basal angiosperms, i.e., Amborellaceae, Nymphaeaceae, and Austrobaileyaceae (Tobe et al , 2007Fig. 1d).…”

Section: Comparisons With the Dioscoreales And Pandanalesmentioning

confidence: 98%

Embryology of Japonolirion (Petrosaviaceae, Petrosaviales): a comparison with other monocots

Tobe

2008

J Plant Res

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Japonolirion osense, the sole species of the genus, endemic to Japan, which is placed together with Petrosavia in the Petrosaviaceae and the order Petrosaviales, is still poorly known with respect to systematic characters. Here I present an embryological study of the anther, ovule, and seed of J. osense. Japonolirion is characterized by a glandular anther tapetum, simultaneous cytokinesis in the microspore mother cell, two-celled mature pollen grains, anatropous and crassinucellate ovules, a two-cell-layered nucellar cap formed early in ovule development, antipodal cells hypertrophied in post-fertilization stages, the ab initio cellular mode of endosperm formation, and exotegmic seeds. Comparisons with the basal monocots Acorus (Acorales) and Araceae (Alismatales), and with the more derived monocots Nartheciaceae (Dioscoreales) and Velloziaceae/Triuridaceae (Pandanales), showed that Japonolirion is clearly distinct from those basal and more derived monocots, supporting a distinct position for Petrosaviaceae or Petrosaviales within the monocots. Extensive comparisons further suggest that the two-cell-layered nucellar cap, whose cells are rich in cytoplasm at the time of fertilization in Japonolirion and thus obviously function as the obturator, is likely to be a common characteristic of the basal monocots and may even be a link with the magnoliids.

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Development and structure of the female gametophyte in Austrobaileya scandens (Austrobaileyaceae)

Cited by 25 publications

References 21 publications

Female gamete competition in an ancient angiosperm lineage

Female gamete competition in an ancient angiosperm lineage

Ancestral traits and specializations in the flowers of the basal grade of living angiosperms

Embryology of Japonolirion (Petrosaviaceae, Petrosaviales): a comparison with other monocots

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