The key difference between carposporophyte and tetrasporophyte is that carposporophyte is a diploid thallus that produces carposporangia containing diploid carpospores while tetrasporophyte is a diploid structure that produces tetrasporangia containing haploid tetraspores.
Red algae belong to phylum Rhodophyta. They are marine algae that appear in red colour due to a pigment called phycoerythrine. Moreover, they are multicellular thalli forming branched algae. Their life cycle has three multicellular stages including two sporophytes and one gametophyte stage. Two sporophytes occur in succession. The two sporophytes are called carposporophyte and tetrasporophyte. The zygote develops into carposporophyte while diploid carpospores germinate and give rise to tetrasporophytes. Tetraspores grow into gametophytes.
CONTENTS
1. Overview and Key Difference
2. What is Carposporophyte
3. What is Tetrasporophyte
4. Similarities Between Carposporophyte and Tetrasporophyte
5. Side by Side Comparison – Carposporophyte vs Tetrasporophyte in Tabular Form
6. Summary
What is Carposporophyte?
Carposporophyte is an individual form that develops from the diploid zygote. Therefore, carpospore is a diploid thallus. It is a unique red algal stage. It has different parts: gonimoblast filaments, carposporangia, carpospores and placental cells. Young vegetative filaments envelop the above-mentioned structures and form the carposporephyte. It is an urn-shaped structure. The wall of the carposporophyte is called the pericarp while the opening is called the ostiole. The whole carposporophyte is dependent on the female gametophyte.
Figure 01: Carposporephyte
Carposporophyte produces non-motile asexual spores called carpospores. They are diploid spores. Carposporophyte releases carpospores through the ostiole into the water. Then carpospores germinate and give rise to diploid adult algal form called tetrasporophyte.
What is Tetrasporophyte?
Tetrasporophyte is the adult stage of red algae. It is formed from the germination of diploid non-motile carpospores. It is also a diploid thallus. Tetrasporophytes morphologically resemble the gametophytic plants of red algae. Tetrasporophyte thallus is laterally branched. From pericentral cells, tetrasporophyte produces sporangia called tetrasporongia, which are sac-like in structure. Inside the tetrasporangia, asexual spores called tetraspores are produced and released to the outside by rupturing the sporangium wall.
Figure 02: Tetrasporophyte
From each diploid nucleus of tetrasporangium, four tetraspores are produced tetrahedrally. They are haploid spores which give rise to gametophytes. Therefore, out of four tetraspores, two develop into male gametophytes while the other two spores develop into the female gametophyte.
What are the Similarities Between Carposporophyte and Tetrasporophyte?
- Carposporephyte and tetrasporophyte are two stages unique to the red algal life cycle.
- Tetrasporophyte is formed by the germination of diploid carpospores.
- Both carposporophyte and tetrasporophyte are diploid structures.
- They produce asexual non-motile spores for asexual reproduction.
What is the Difference Between Carposporophyte and Tetrasporophyte?
Carposporophyte is a diploid stage which produces diploid carpospores in red algae while tetrasporophyte is an adult stage of red algae which produces haploid tetraspores. So, this is the key difference between carposporophyte and tetrasporophyte. Carposporophyte develops from the diploid zygote while tetrasporophyte develops from the germination of carpospore. Moreover, carposporophyte has carposporangia while tetrasporophyte has tetrasporangia.
Furthermore, carposporophyte produces carpospores by mitosis while tetrasporophyte produces tetraspores by meiosis. Also, another difference between carposporophyte and tetrasporophyte is that carposporophyte is dependent on female gametophyte while tetrasporophyte is free living.
Below infographic shows a detailed comparison of the difference between carposporophyte and tetrasporophyte.
Summary – Carposporophyte vs Tetrasporophyte
Carposporophyte and tetrasporophyte are two diploid phases of red algae life cycle. Carposporephyte is an urn-shaped diploid structure formed from the diploid zygote. It produces carpospores. When carpospores germinate, the adult algal form known as tetrasporophyte is formed. It is also a diploid stage which resembles gametophyte morphologically. It produces tetraspores by meiotic cell division. Therefore, tetraspores are haploid and give rise to gametophytes of red algae. Carposporophyte is dependent on female gametophyte while tetrasporophyte is free living. Thus, this is the difference between carposporophyte and tetrasporophyte.
Reference:
1. “General Characters of Rhodophyceae & Life Cycle of Polysiphonia S…” LinkedIn SlideShare, 22 Aug. 2019, Available here.
2. “Red Algae (Polysiphonia).” Virtual Class Biology, Available here.
Image Courtesy:
1. “Polysiphonia cystocarp WM” By Curtis Clark – Own work (CC BY-SA 3.0) via Commons Wikimedia
2. “Rhod1005” By Jon Houseman – Jon Houseman and Matthew Ford (CC BY-SA 3.0) via Commons Wikimedia