Example Of A Gametophyte
In extant land plants, either the sporophyte or the gametophyte may be reduced (heteromorphic). In bryophytes (mosses, liverworts, and hornworts), the gametophyte is the most visible stage of the life cycle. May 26, 2019 In ferns, the gametophyte is a separate plant, very small, like a 1 - 2 cm leaf flat on the soil. Some create male germ cells or gametes, some female gametes. When the two unite, carried by air or water, the resulting zygote, diploid, grows into the adult fern, the sporophyte.
The key difference between sporophyte and gametophyte is that the sporophyte is a diploid structure that participates in asexual reproduction while the gametophyte is a haploid structure that participates in sexual reproduction of plants.
Plants reproduce via asexual reproduction as well as via sexual reproduction. During the evolution of plant life, a variation can be seen in the development of the reproductive system of a plant depending on the complexity of the plant category. In the evolution of plants, we encounter six different plant categories namely Bryophytes, Psilophytes, Lycophytes, Sphenophytes, Pteridophytes and Spermatophytes. When considering all six types, the reproductive systems of each category are different from each other. In most plants, the sexual reproduction occurs by two different phases called meiosis and fertilization. By meiosis and fertilization, the life cycle of a plant divides into two distinct phases named sporophyte generation and gametophyte generation. During the reproduction process, these two phases take place alternatively and hence called Alternation of Generations. In some plants, sporophyte generation is dominant than the gametophyte generation while in some groups of plants, gametophyte generation is dominant.
CONTENTS
1. Overview and Key Difference
2. What is Sporophyte
3. What is Gametophyte
4. Similarities Between Sporophyte and Gametophyte
5. Side by Side Comparison – Sporophyte vs Gametophyte in Tabular Form
6. Summary
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What is Sporophyte?
Sporophyte represents the asexual generation of a plant. It is a diploid structure having two sets of chromosomes in cells. Sporophyte generation is dominant in higher plants such as angiosperms and gymnosperms as well as in pteridophytes. Besides, this generation begins with the formation of diploid zygote upon fertilization of two types of gametes. The zygote divides by mitosis and grows into a diploid sporophyte.
Moreover, sporophytes bear sporangia, and by the process called meiosis (which reduces the number of chromosomes in a cell to half of its parents’ cells), the diploid sporophyte produces haploid spores. These haploid spores germinate and eventually grow as multicellular haploid structures called gametophytes which give rise to the next gametophyte generation which is a sexual phase. Furthermore, these haploid spores participate in the formation of new plants via asexual reproduction.
What is Gametophyte?
Gametophyte represents the sexual phase of the plant life cycle. It is a haploid phase that is dominant in lower plants such as bryophytes and algae. With evolution, gametophyte generation has become smaller and restricted into single cells. Gametophyte phase begins with the formation of haploid spores by sporophytes.
Figure 02: Gametophyte
Accordingly, spores divide by mitosis and develop into the multicellular haploid structure known as gametophyte. Also, by dividing again through mitosis, gametophytes produce haploid male and female gametes (egg and sperms) in order to carry out sexual reproduction. These male and female gametes fuse during the sexual reproduction and form a diploid cell called zygote. Then, the zygote starts the next generation which is the sporophyte generation. Likewise, alternation of generation continues in plants.
What are the Similarities Between Sporophyte and Gametophyte?
- Sporophyte and gametophyte are two stages of the plant life cycle.
- These stages help alternating generations via haploidy and diploidy.
- Also, both are multicellular structures.
- Furthermore, both produce haploid cells (spores or gametes).
What is the Difference Between Sporophyte and Gametophyte?
Sporophyte represents the diploid phase (2N) due to the formation of zygote, while gametophyte represents the haploid phase (N) due to the occurrence of meiosis. Therefore, this is the key difference between sporophyte and gametophyte. Besides, the sporophyte phase produces haploid spores, while the gametophyte phase produces male and female gametes (egg and sperms). Therefore, the sporophyte phase is asexual, while the gametophyte phase is sexual. Hence, it is also a difference between sporophyte and gametophyte.
Moreover, a further difference between sporophyte and gametophyte is that the diploid zygote is the first cell in a sporophyte generation, and the haploid spore is the first cell in the gametophyte generation. Also, in Bryophytes, Psilophytes, and Lycophytes, the gametophyte stage is larger and dominant, and the sporophyte stage grows on the gametophyte stage. In angiosperms and gymnosperms, the sporophyte phase is the larger and dominant comparatively, while the gametophyte phase is comparatively smaller. Hence, it is another difference between sporophyte and gametophyte.
Below is an infographic on the difference between sporophyte and gametophyte that provides more information on the differences.
Summary – Sporophyte vs Gametophyte
Alteration of generation is a common feature in the life cycle of plants. Hence, the life cycle goes via two distinct phases; the asexual phase and the sexual phase. The asexual phase represents the sporophyte generation while the sexual phase represents by the gametophyte generation. Moreover, sporophytes are diploid and have double sets of chromosomes. On the other hand, gametophytes are haploid and have a single set of chromosomes. So, this is the key difference between sporophyte and gametophyte. Furthermore, sporophyte produces haploid spores while the gametophyte produces male and female gametes. In bryophytes and algae, gametophyte generation is dominant while in pteridophytes, gymnosperms and angiosperms, the gametophyte generation is dominant. Thus, this summarizes the difference between sporophyte and gametophyte.
Reference:
1. “Alternation of Generations.” Wikipedia, Wikimedia Foundation, 20 Dec. 2018. Available here
2. Study.com, Study.com. Available here
Image Courtesy:
1.”Marchantia sporophytes”By Jon Houseman – Jon Houseman and Matthew Ford, (CC BY-SA 3.0) via Commons Wikimedia
2.”Gametophyte2″By Random Tree – Own work, (CC BY-SA 3.0) via Commons Wikimedia