関: sporophore

WordNet

the spore-producing individual or phase in the life cycle of a plant having alternation of generations
a spore-bearing branch or organ: the part of the thallus of a sporophyte that develops spores; in ferns and mosses and liverworts is practically equivalent to the sporophyte

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2016/06/17 21:18:15」(JST)

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Young sporophytes of the common moss Tortula muralis. In mosses, the gametophyte is the dominant generation, while the sporophytes consist of sporangium-bearing stalks growing from the tips of the gametophytes

A sporophyte (/spɔːroʊˌfaɪt/) is the diploid multicellular stage in the life cycle of a plant or alga. It develops from the zygote produced when a haploid egg cell is fertilized by a haploid sperm and each sporophyte cell therefore has a double set of chromosomes, one set from each parent. All land plants, and most multicellular algae, have life cycles in which a multicellular diploid sporophyte phase alternates with a multicellular haploid gametophyte phase. In the seed plants, the Gymnosperms and flowering plants (Angiosperms), the sporophyte phase is more prominent than the gametophyte, and is the familiar green plant with its roots, stem, leaves and cones or flowers. In flowering plants the gametophytes are very reduced in size, and are represented by the pollen and the embryo sac.

The sporophyte produces spores (hence the name) by meiosis, a process also known as "reduction division" that reduces the number of chromosomes in each spore mother cell by half. The resulting meiospores develop into a gametophyte. Both the spores and the resulting gametophyte are haploid, meaning they only have one set of chromosomes. The mature gametophyte produces male or female gametes (or both) by mitosis. The fusion of male and female gametes produces a diploid zygote which develops into a new sporophyte. This cycle is known as alternation of generations or alternation of phases.

In flowering plants, the sporophyte comprises the whole multicellular body except the pollen and embryo sac

Bryophytes (mosses, liverworts and hornworts) have a dominant gametophyte phase on which the adult sporophyte is dependent for nutrition. The embryo sporophyte develops by cell division of the zygote within the female sex organ or archegonium, and in its early development is therefore nurtured by the gametophyte.^[1] Because this embryo-nurturing feature of the life cycle is common to all land plants they are known collectively as the Embryophytes.

Cleistocarpous sporophyte of the moss Physcomitrella patens

Most algae have dominant gametophyte generations, but in some species the gametophytes and sporophytes are morphologically similar (isomorphic). An independent sporophyte is the dominant form in all clubmosses, horsetails, ferns, gymnosperms, and angiosperms (flowering plants) that have survived to the present day. Early land plants had sporophytes that produced identical spores (isosporous or homosporous) but the ancestors of the gymnosperms evolved complex heterosporous life cycles in which the spores producing male and female gametophytes were of different sizes, the female megaspores tending to be larger, and fewer in number, than the male microspores.

During the Devonian period several plant groups independently evolved heterospory and subsequently the habit of endospory, in which the gametophytes develop in miniaturized form inside the spore wall. By contrast in exosporous plants, including modern ferns, the gametophytes break the spore wall open on germination and develop outside it. The megagametophytes of endosporic plants such as the seed ferns developed within the sporangia of the parent sporophyte, producing a miniature multicellular female gametophyte complete with female sex organs, or archegonia. The oocytes were fertilized in the archegonia by free-swimming flagellate sperm produced by windborne miniaturized male gametophytes in the form of pre-pollen. The resulting zygote developed into the next sporophyte generation while still retained within the pre-ovule, the single large female meiospore or megaspore contained in the modified sporangium or nucellus of the parent sporophyte. The evolution of heterospory and endospory were among the earliest steps in the evolution of seeds of the kind produced by gymnosperms and angiosperms today.

References

^ Ralf Reski(1998): Development, genetics and molecular biology of mosses. In: Botanica Acta. Bd. 111, S. 1-15.

P. Kenrick & P.R. Crane (1997) The origin and early evolution of plants on land. Nature 389, 33-39.
T.N. Taylor, H. Kerp and H. Hass (2005) Life history biology of early land plants: Deciphering the gametophyte phase. Proceedings of the National Academy of Sciences 102, 5892-5897.
P.R. Bell & A.R. Helmsley (2000) Green plants. Their Origin and Diversity. Cambridge University Press ISBN 0-521-64673-1

English Journal

O father where art thou? Paternity analyses in a natural population of the haploid-diploid seaweed Chondrus crispus.

Krueger-Hadfield SA1, Roze D2, Correa JA3, Destombe C2, Valero M2.
Heredity.Heredity (Edinb).2015 Feb;114(2):185-94. doi: 10.1038/hdy.2014.82. Epub 2014 Sep 17.
The link between life history traits and mating systems in diploid organisms has been extensively addressed in the literature, whereas the degree of selfing and/or inbreeding in natural populations of haploid-diploid organisms, in which haploid gametophytes alternate with diploid sporophytes, has be
PMID 25227258

Developing sporophytes transition from an inducible to a constitutive ecological strategy of desiccation tolerance in the moss Aloina ambigua: effects of desiccation on fitness.

Stark LR1, Brinda JC2.
Annals of botany.Ann Bot.2015 Jan 11. pii: mcu252. [Epub ahead of print]
BACKGROUND AND AIMS: Two ecological strategies of desiccation tolerance exist in plants, constitutive and inducible. Because of difficulties in culturing sporophytes, very little is known about desiccation tolerance in this generation and how desiccation affects sexual fitness.METHODS: Cultured spor
PMID 25578378

The FRK1 mitogen-activated protein kinase kinase kinase (MAPKKK) from Solanum chacoense is involved in embryo sac and pollen development.

Lafleur E1, Kapfer C1, Joly V1, Liu Y1, Tebbji F2, Daigle C1, Gray-Mitsumune M1, Cappadocia M1, Nantel A3, Matton DP4.
Journal of experimental botany.J Exp Bot.2015 Jan 8. pii: eru524. [Epub ahead of print]
The fertilization-related kinase 1 (ScFRK1), a nuclear-localized mitogen-activated protein kinase kinase kinase (MAPKKK) from the wild potato species Solanum chacoense, belongs to a small group of pMEKKs that do not possess an extended N- or C-terminal regulatory domain. Initially selected based on
PMID 25576576