Main Difference – Zoospores vs Aplanospores
Zoospores and aplanospores are two types of spores produced by algae and fungi during asexual reproduction. Fungi produce spores in three ways: sexually, asexually and vegetatively. Asexual spores of fungi are produced by mitosis. They are not resistant to unfavorable conditions. But, they exhibit rapid multiplication. Asexual spores occur in two ways: endogenously and exogenously. Both zoospores and aplanospores are endogenous spores. Endogenous spores are produced internally within a sac by cell division of the protoplasm. The main difference between zoospores and aplanospores is that zoospores are motile spores whereas aplanospores are non-motile spores.
This article explains,
1. What are Zoospores
– Definition, Structure, Features, Examples
2. What are Aplanospores
– Definition, Structure, Features, Examples
3. What is the difference between Zoospores and Aplanospores
What are Zoospores
Zoospores are motile asexual spores found in algae, fungi, and protozoans. They are produced in an asexual structure called zoosporangium. They use flagella for their locomotion. Zoospores are specialized structures for dispersal. Hence, they are incapable of dividing and absorbing organic nutrients during germination. They encyst by shedding their flagella and secreting a cell wall.
Features of Zoospores
Three common features are shared by zoospores.
- Zoospore cells are wall-less.
- Endogenous food reserves are used for the locomotion.
- They are capable of responding to environmental signals in order to decide where to locate and where to encyst.
Figure 1: An asexual zoospore of Phytophthora
What are Aplanospores
Aplanospores are non-motile asexual spores found in certain algae and fungi. They are formed from a part of a protoplast of a vegetative cell. Aplanospores consist of a cell wall, which is different from the original parental cell wall, allowing the survival of the organism in harsh conditions. Haematococcus Pluvialis forms cell aggregates due to the nitrogen deprivation. These aggregates finally become aplanospores.
Figure 2: Aplanospores of Haematococcus Pluvialis
Difference Between Zoospores and Aplanospores
Definition
Zoospores: A zoospore is a motile asexual spore produced by certain algae, fungi, and protozoans.
Aplanospores: An aplanospores is a nonmotile asexual spore produced by certain algae and fungi.
Occurrence
Zoospores: Zoospores occur in Phycomycetes.
Aplanospores: Aplanospores occur in green algae.
Motility
Zoospores: Zoospores are motile.
Aplanospores: Aplanospores are non-motile.
Cell Wall
Zoospores: Zoospores do not possess a true cell wall.
Aplanospores: Aplanospores possess a true cell wall.
Size
Zoospores: Zoospores are small in size.
Aplanospores: Aplanospores are large compared to zoospores.
Significance
Zoospores: Zoospores are incapable of undergoing harsh environmental conditions.
Aplanospores: Aplanospores are capable of undergoing harsh environmental conditions due to the presence of a cell wall.
Examples
Zoospores: Oomycota like Phytophthora, Chytridiomycota, Myxomycota and Plasmodiophoromycota as well as Opisthokonts and heterokonts produce zoospores.
Aplanospores: Lower fungi, algae like Haematococcus Pluvialis, Chlamydomonas and Vaucheria produce aplanospores.
Conclusion
Zoospores and aplanospores are asexual spores produced endogenously in fungi, algae, and protozoans. Zoospores are motile and aplanospores are non-motile. Zoospores lack a proper cell wall to endure harsh environmental conditions. Hence, they are not considered as resistant units of organisms. In contrast, aplanospores are capable of undergoing harsh environmental conditions due to the presence of a hard cell wall. Therefore, the main difference between zoospores and aplanospores is their structure.
Reference:
1.”Spores in Fungi.” My Agriculture Information Bank. N.p., n.d. Web. 16 May 2017. <http://agriinfo.in/?page=topic&superid=5&topicid=1990>.
2. Deacon, Jim. “The Microbial World: Fungal zoospores.” Zoospores. N.p., n.d. Web. 16 May 2017. <http://archive.bio.ed.ac.uk/jdeacon/microbes/zoospore.htm>.
3. “Aplanospore.” Merriam-Webster. Merriam-Webster, n.d. Web. 16 May
Image courtesy:
1. “Zoospores – Reproductive Structure of the Phytophthora”- Reproduced courtesy of Matteo Garbelotto, UC Berkeley [A, D], and Edwin R. Florance, Lewis & Clark College [Portland, Oregon, United States] and the USDA Forest Service Pacific Southwest Research Station in Albany, California [B, C].) – (Public Domain) via Commons Wikimedia
2. “Haematococcus pluvialis aggregate” By Ude – Own work (CC BY-SA 3.0) via Commons Wikimedia
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