Difference Between Unilocular and Plurilocular Sporangia

Main Difference – Unilocular vs Plurilocular Sporangia

Unilocular and plurilocular are two types of sporangia produced by Ectocarpus. Ectocarpus is a type of filamentous brown algae, consisting of one of the simplest thalli in brown algae. Ectocarpus grows on rocks or large algae. Ectocarpus shows alterations of generations with a diploid sporophyte and a haploid gametophyte. Both sporophyte and gametophyte show similar morphology. The sporophyte produces either unilocular or plurilocular sporangia. The main difference between unilocular and plurilocular sporangia is that unilocular sporangia consist of a single enlarged cell, which undergoes meiosis followed by mitosis, forming haploid zoospores whereas plurilocular sporangia consist of a large number of cuboidal cells, which develops into diploid zoospores. Unilocular sporangia are common at cooler temperatures whereas plurilocular sporangia are common at warmer temperatures.

Key Areas Covered

1. What are Unilocular Sporangia
      – Definition, Features, Type of Zoospores
2. What are Plurilocular Sporangia
      – Definition, Features, Type of Zoospores
3. What are the Similarities Between Unilocular and Plurilocular Sporangia
      – Outline of Common Features
4. What is the Difference Between Unilocular and Plurilocular Sporangia
      – Comparison of Key Differences

Key Terms: Brown Alage, Ectocarpus, Gametophyte, Plurilocular Sporangia, Unilocular Sporangia, Zoospores

What are Unilocular Sporangia

Unilocular sporangia are a type of sporangia produced by a brown algae, Ectocarpus. Unilocular sporangia consist of an enlarged, single cell, which undergoes meiosis to produce haploid zoospores. The unilocular sporangia develop from the terminal cells of the small branchlets. The terminal cell increases in size gradually and becomes ellipsoidal. The meiotic cell division of the unilocular sporangia is followed by a series of mitotic cell divisions and produce 32-64 zoospores. These zoospores are haploid. The zoospores of the unilocular sporangia are called meiozoospores since they are produced by meiosis. The unilocular sporangia of Ectocarpus are shown in figure 1.

Difference Between Unilocular and Plurilocular Sporangia

Figure 1: Ectocarpus unilocular sporangia

What are Plurilocular Sporangia

Plurilocular sporangia are the other type of sporangia produced by the brown algae, Ectocarpus. Plurilocular sporangia also develop from the terminal cells of the branchlets. These are spherically elongated structures. A row of 5-12 cells is produced in the plurilocular sporangium. Then vertical mitotic cell divisions start from the median cell of the row. Ectocarpus produces unilocular sporangia at 13 °C and plurilocular sporangia at 19 °C. Both unilocular and plurilocular sporangia are formed at 16 °C. The Ectocarpus plurilocular sporangia are shown in figure 2.

Main Difference - Unilocular vs Plurilocular Sporangia

Figure 2: Ectocarpus plurilocular sporangium

Similarities Between Unilocular and Plurilocular Sporangia

Both unilocular and plurilocular sporangia are produced by a filamentous brown algae,
Both unilocular and plurilocular sporangia are produced by the sporophyte.
Both unilocular and plurilocular sporangia are involved in asexual reproduction.
Both unilocular and plurilocular sporangia produce biflagellated zoospores.

Definition

Unilocular Sporangia: The sporangia that consist of a single loculus or cavity are referred to as unilocular sporangia.

Plurilocular Sporangia: The sporangia that consist of several compartments are referred to as plurilocular sporangia.

Formation

Unilocular Sporangia: Unilocular sporangia are common at cooler temperatures.

Plurilocular sporagia: Plurilocular sporangia are common at warmer temperatures.

Number of Cells in the Sporangia

Unilocular Sporangia: Unilocular sporangia are composed of a single cell.

Plurilocular Sporagia: Plurilocular sporangia are composed of a large number of cuboidal cells.

Sporangia

Unilocular Sporangia: The unilocular sporangia are ellipsoidal.

Plurilocular Sporangia: The plurilocular sporangia are spherically elongated structures.

Zoospores

Unilocular Sporangia: Unilocular sporangia produce haploid zoospores.

Plurilocular Sporagia: Plurilocular sporagia produce diploid zoospores.

Conclusion

Unilocular and plurilocular sporangia are the two types of sporangia produced by Ectocarpus in response to the environmental temperature. The unilocular sporangia are produced in cooler temperatures whereas the plurilocular sporangia are produced in warmer temperatures. The unilocular sporangia are formed from the enlargement of a single cell. The plurilocular sporangia are formed from a large number of cuboidal cells. The unilocular sporangia produce haploid zoospores whereas plurilocular sporangia produce diploid zoospores. The main difference between unilocular and plurilocular sporangia is the formation of each type of sporangia and the type of zoospores produced by them.

References:

1. “Ionic and Covalent Bonds.” Chemistry LibreTexts. Libretexts, 03 Mar. 2017. Web. Available here. 11 Aug. 2017.
2. Helmenstine, Anne Marie. “Understand What a Covalent Bond Is in Chemistry.” ThoughtCo. N.p., n.d. Web. Available here. 11 Aug. 2017.

Image Courtesy:

1.” Ectocarpus unilocular structure” By Curtis Clark – Own work (CC BY-SA 3.0) via Commons Wikimedia
2. “Phaeophyta Ectocarpus plurilocular sporangium 09” by Bruce Kirchoff (CC BY 2.0) via Flickr