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 ?
After 7 and 30 days, small sporophytes of all three species were significantly more discolored than gametophytes and large sporophytes at concentrations [less than or equal to] 0.
Male and Female Gametophyte Development in Cichorium intybus, Int.
Similar to axons in the development of the nervous system, the directional growth of pollen tubes is controlled by multifarious interactions with the sporophytic pistil and the female gametophyte (Okuda & Higashiyama, 2010).
Water relations are discussed in some detail with a focus on desiccation tolerance (very low cellular water content) of the gametophytes.
Spore germination was not inhibited by the presence of increased As, and gametophyte morphology showed deleterious effects only when grown for extended time periods on a growth medium with extremely high As concentrations ([greater than or equal to] 600 ppm).
Example: In pine trees, the immature male gametophyte is a megaspore, the embryonic pine seed, a pollen tube or a pollen grain?
To distinguish species and generate phylogenetic hypotheses, taxonomists working on the group have incorporated evidence from diverse datasets, including spore morphology (Wilce, 1972; Tryon and Lugardon, 1991), spore abortion (Beitel and Mickel 1992; Wagner and Beitel 1993), gametophyte morphology (Bruce, 1976), secondary metabolite production (Pedersen and 011gaard, 1982), and sporangium anatomy (Wilce, 1965; 011gaard, 1975).
Diploid female gametophyte formation in 24-chromosome potatoes: genetic evidence for the prevalence of the second meiotic division restitution mode.
Influence of drought stress in femole gametophyte development in corn and subsequent grain yield.
3 mm) were fed 1 of 5 benthic diatoms and a gametophyte of a macroalga, Undaria pinnatifida, for 21 days.
Sporophyte recruitment began in late February and peaked in June, suggesting a gametophyte period of approximately 6 months.