sporophyte

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sporophyte:

see gametophytegametophyte
, 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.
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Sporophyte

 

an asexual generation in plants which is formed from a zygote and in which alternation of generations is part of the developmental cycle. Sporophytes develop sporangia, which bear spores by means of meiosis. The sporophyte alternates with the gametophyte—the sexual generation—which is formed from a spore and which forms gametes. The merging of gametes produces a zygote. The cells of the sporophyte and those of the zygote have a diploid set of chromosomes, whereas the cells of the gametophyte have a haploid set.

The sporophyte represents different stages in the developmental cycles of different plants. In gymnosperms and angiosperms it plays a dominant role, ensuring the development of greatly reduced gametophytes (male gametophytes are pollen grains; female ones are the primary endosperm and the embryo sac). It also dominates in ferns and laminarians, whose gametophytes (prothallia) exist separately from the sporophytes. The sporophyte occupies a subordinate position in mosses, where it is represented by a sporogonium on the gametophyte, and in a few brown algae, where it exists independently.

In plants with isomorphic cycles of development, such as some green and brown algae, independently existing sporophytes and gametophytes are marked by a morphologically similar development. In a majority of Florideae (red algae) the sporophyte seems to have two phases of development: the first, the carpospo-rophyte, develops on the gametophyte; the second lives independently and develops similarly to the gametophyte. Hetero-morphic cycles of development, with a sporophyte that produces numerous spores, are especially characteristic of all higher plants except mosses. The establishment in plants of such cycles of development is due to the emergence of algal ancestors onto dryland, where reproduction by spores was more advantageous. The transition from isospory to heterospory led to the development of seeds and to a more perfect type of reproduction in plants—seed reproduction.

A. N. SLADKOV

sporophyte

[′spȯr·ə‚fīt]
(botany)
An individual of the spore-bearing generation in plants exhibiting alternation of generation.
The spore-producing generation.
The diplophase in a plant life cycle.
References in periodicals archive ?
Light and electron microscopic study on the mycorrhizae of sporophytes of Botrychium virginianum-arbuscular structure resembling fossil forms.
The mean concentration of lead in sporophytes was compared between treatments by ANOVA followed by the Dunnett test, with a level of significance of 5%.
Morphological studies on some species of Blechnum, Doodia, Woodwardia and Stenochlaena-I: The gametophytes and juvenile sporophytes. J.
Oligoalginate recognition and oxidative burst play a key role in natural and induced resistance of sporophytes of Laminariales.
Gametophyte sexual dimorphism contributes to the variance among haploid sibs derived from a diploid sporophyte, and inflates this term, which therefore biases our test for epistasis.
Putatively beginning with a more simple general thalloid body plan like that of today's Monoclea (Schuster, 1992) or Blasia (Renzaglia et al., 2007), the Marchantiopsida radiated to give rise to forms with elaborate elevated gametangiophores and reduced forms with receptacles hidden within the thallus, reduced sporophytes and loss of elaters.
The aim of this study was to investigate germination of megaspores and initial development of sporophytes of Regnellidium diphyllum in the presence of nickel, providing information on the influence of this metal in the establishment and growth of the species.
(2003) found that juveniles 2.8-2.9 mm in shell length grew 100 [micro]m [day.sup.-1] on this diatom species, which was comparable to growth rates achieved on juvenile sporophytes of the macroalga Laminaria japonica.
A protocol has been developed that consistently yields viable protoplasts that are capable of regeneration, development into fertile gametophytes, and production of sporophytes. Furthermore, the protoplasts follow a path of regeneration in which a primary rhizoid is formed with the first cell division, thus resembling spore germination.