Every living organism goes through a certain life cycle: from conception (laying) to death (death), and plants are no exception. Their distinguishing feature is the reproduction process, which consists in the alternation of sporophyte and gametophyte.
But what is a gametophyte - we will analyze in more detail in this article. It should be said that quite often the gametophyte is not isolated, but exists together with the sporophyte or directly depends on it.
What is a gametophyte?
The term "gametophyte" comes from the Greek word "gamete", i.e. reproductive cell and phyton (plant) and in translation means the sexual generation or one of the stages of plant development. In biology, the haploid sexual generation has a letter designation - "n".
Views
To understand what a gametophyte is, you need to understand how it is formed and what it is. The gametophyte is a distinctive feature that characterizes the belonging of plants to the class of higher spores. Depending on the differentiation in the gametophyte, gametangia (generative organssexual reproduction) of two types: female and male.
Features of reproduction
The whole process of sexual reproduction in plants occurs in the form of conjugation (ie, the fusion of protoplasts of two independent vegetative cells). Often, both gametes and spores can develop simultaneously on the same individual. But there are also such cases when spores develop only on one species, and gametes exclusively on another. An individual on which spores develop is called a sporophyte, and one on which gametes are formed is called a gametophyte.
Gametophyte in plants
Gametophyte is bisexual and unisexual. In the sporophyte, the nuclei have a diploid chromosome set, but in the gametophyte they are haploid. The predominant majority of highly organized algae and almost all higher plants have a clear pattern in the cyclic development and alternation of generations that reproduce asexually and sexually.
Schematically, the reproduction process can be represented as follows: gametophyte → gamete production → gamete fusion → zygote formation → diploid sporophyte development → and so on.
The structure of the gametophyte is quite diverse and it directly depends on the types of generational change in certain plant species. So, for example, in algae, a uniform change of generations (isomorphic) is observed, therefore their gametophyte is represented by an independent unit that exists separately and is no different from the same sporophyte.
Butkelp algae, which have a distinctive (heteromorphic) development cycle, the gametophyte has a completely different structure, different from the sporophyte, in the form of underdeveloped filamentous and branched thalli. In almost all representatives of sporophytes, including ferns, the gametophyte is completely underdeveloped and exists for a very short time.
Due to the fact that in the course of evolution in plants of higher classes a smooth reduction of the gametophyte was observed, they lost their gender. For example, seed plants have completely lost the female generation, and all stages of their development occur on the sporophyte.
The female gametophyte of gymnosperms is represented by multicellular haploid endospermia or several archegoniums, as in pine or other gymnosperms, respectively. In isosporous representatives of fern-like plants, the growths have both sexes.
The male gametophyte of seed plants has the appearance of pollen and originates from a microspore that forms gametes, growing into a pollen tube. But the growths of isosporous ferns are bisexual.
Thus, the gametophyte does not depend on the timing of the growing season or the life of the plant, but only on its species and evolutionary features.
Conclusion
Thus, the gametophyte, being a sexual generation in the development of plants and characterized by a certain and consistent alternation of generations within its species, has several features. First of all, it is formed from spores, has a haploid set of chromosomes and always formsgametes, regardless of whether they are specialized reproductive organs or ordinary vegetative cells.
Now you know what a gametophyte is and what are its features.
