When we study the reproductive cycle of plants, two terms are quite common: gametophytes and sporophytes. But what do they mean? What is the importance of each of them in the reproductive cycle? Next, we will learn what gametophyte and sporophyte are.
→ What is gametophyte?
Gametophyte is the name given to the haploid (n) generation that produces gametes in plants. Gametes are haploid reproductive cells that fuse in the process of fertilization, giving rise to diploid organisms.
In the bryophytes, the gametophyte stage is the dominant stage of the life cycle, unlike vascular plants (pteridophytes, gymnosperms and angiosperms). The gametophyte in bryophytes is independent of the sporophyte and also more complex (see figure at the beginning of the text). In other groups of plants, in turn, the gametophyte is less complex and usually nutritionally dependent on the sporophyte.
→ What is a sporophyte?
Sporophyte is the name of the diploid (2n) and spore-producing generation in plants. The spores, which are produced on the sporophyte in a process of
meiosis, are nothing but cells capable of dividing by mitosis and give rise to a new haploid multicellular organism. Spores differ from gametes in that they do not need to fuse with another to generate a new individual.In bryophytes, this life phase is gametophyte dependent and represents the transitory phase of the life cycle of these plants. In vascular plants, in turn, the sporophyte is larger and more complex than the gametophyte (see figure below).
The dominant stage in pteridophytes is the sporophyte. The fern serum (figure) is where the spores are produced.
→ alternation of generations
In plants and some algae, there is a rotation between haploid and diploid generations during the life cycle, and this phenomenon is called alternation of generations. In algae, it is common for the haploid and diploid forms to be quite similar in external appearance; in this case, it's called alternation of isomorphic generations.In brown and red plants and algae, there is a alternation of heteromorphic generations, since gametophytes (haploids) and sporophytes (diploids) are visibly different from each other.
By Ma. Vanessa Sardinha dos Santos
Source: Brazil School - https://brasilescola.uol.com.br/o-que-e/biologia/o-que-sao-gametofito-esporofito.htm