gametophyte

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gametophyte

(gəmē`təfīt'), phase of plant life cycles in which the gametes, i.e., egg and sperm, are produced. The gametophyte is haploid, that is, each cell contains a single complete set of chromosomes, and arises from the germination of a haploid spore. In many lower plants, the gametophyte phase is the dominant plant form; for example, the familiar mosses are the gametophyte form of the plants. The alternate phase of the plant life cycle is the sporophyte, the diploid plant form, with each cell containing two complete sets of chromosomes. For example, in mosses the sporophyte is a capsule atop a slender stalk that grows out of the top of the gametophyte. The sporophyte develops from the union of two gametes, such as an egg fertilized by a sperm; in turn, the sporophyte forms spores that develop into gametophytes. The alternation between haploid gametophyte and diploid sporophyte phases, known as alternation of generations, occurs in all multicellular plants. As plants advanced in evolutionary development, the sporophyte became the increasingly dominant plant form and the gametophyte form has been correspondingly reduced. In contrast to mosses, for example, in the advanced angiosperms the male and female gametophytes are reduced to three-celled and seven-celled structures, respectively, found within the reproductive organs of the familiar flowering plant (the sporophyte). See also fertilizationfertilization,
in biology, process in the reproduction of both plants and animals, involving the union of two unlike sex cells (gametes), the sperm and the ovum, followed by the joining of their nuclei.
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; reproductionreproduction,
capacity of all living systems to give rise to new systems similar to themselves. The term reproduction may refer to this power of self-duplication of a single cell or a multicellular animal or plant organism.
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Gametophyte

 

sexual generation in those plants that exhibit alternation of generations. The gametophyte alternates in the development cycle with the asexual generation or sporophyte. In many plants the gametophyte carries on an autonomous existence, independent of the sporophyte. In some cases it is not distinguishable from the sporophyte by its external appearance (for example, the gametophyte in many algae); in others it is very distinct, for example, in the prothallia of ferns, horsetails, and lycopodia. In angiospermous plants the gametophyte is reduced to a pollen grain (male gametophyte) and to an embryo sac (female gametophyte). The gametophyte cell nuclei are characterized by half the number (haploid) of chromosomes in comparison to the cell nuclei of the sporophyte.

gametophyte

[gə′mēd·ə‚fīt]
(botany)
The haploid generation producing gametes in plants exhibiting metagenesis.
An individual plant of this generation.
References in periodicals archive ?
We also expected (2) that gametophytes would be more susceptible to glyphosate than the other life stages because of their thin laminar structure and lack of a cuticle.
Notably, there is not enough information about anther structure and male gametophyte developmental stages of Azalea alexander L.
Attractive and repulsive interactions between female and male gametophytes in Arabidopsis pollen tube guidance.
First, when one sees a liverwort, hornwort, or moss in the field or elsewhere, the observed specimen, with only a very few exceptions, represents the gametophyte (1n) phase of the organism's heteromorphic alternation of phases (or generations).
When Watkins and his colleagues tested gametophytes of 12 species of tropical ferns, however, most showed some ability to bounce back after drying out.
Development of the flower, gametophytes, and floral vasculature in Cochliostema odoratissimum (Commelinaceae).
Comparative observation of the development of gametophytes of three species in Cyclosorus Link.
Second, spores from unilocular sporangia of some algae may have quite different fates and develop either into gametophytes or into sporophytes, which has been called heteroblasty by Muller (1966).
Adult gametophytes were cordiform-annual and gametangia were of the leptosporangiate type.
It is possible to obtain haploid/DH individuals through different developmental pathways, involving both the female and the male gametophytes (Dunwell, 2010).
Rare independent, filmy fern gametophytes found from the late 1950s and onward at a handful of locations in British Columbia and southeastern Alaska were presumed to be H.
Although alternation of generations initially referred to the alternation of sexual and asexual forms in animals, the term is now almost exclusively associated with the life cycles of plants, specifically with the alternation of haploid gametophytes and diploid sporophytes.