Zoospores are mobile spores that use flagella for their control. Various species of protists, bacteria and fungi use them as a means of propagation. Flagella can be of two types.
Stramopyle flagella (Stromopiles) containing lateral filaments called mastigonum. These are located perpendicular to the main axis of the flagellum. The whip-like flagella lack mastigonum.
The number and distribution of flagella in zoospores will vary depending on the taxonomic group to which the zoospora belongs. There are four main forms of zoospores: Opistoconta, Asokonta, Heterochonta and Zoospora with a single striatal flagellum.
Features
zoospora opistonta
They usually have a single posterior flagellum, except in Neochlamistigales, which present up to 16 flagella. This is typical of Opisthokonta fauna.
Opisthokonts are a group of eukaryotic organisms that together with fungi and fungi are animals. In these flagellums, when present, the latter occupy the position, propelling the cell, as in the spermatozoa of animals.
zoospora anisocotta
It consists of two flagella in the form of whips of different lengths. Both flagella are inserted laterally. The longest one goes later, while the shorter one goes first. It occurs in some myxomycota and plasmodiophoromycota.
zoospora heterocona
These zoospores have two anterior flagella of different sizes and lengths. This type of spore is typical of heterogametic organisms. Heterocontos is a superphylum of eukaryotic organisms.
This includes pluricellular brown algae from unicellular algae, such as diatoms. It also includes oomycetes, which were previously treated as fungi. Among these, the longest flagellum is covered with mastigonemes.
The other flagellum is in the form of a whip and is usually short or very short. The flagella are inserted anteriorly (subprisally) near or posteriorly and are generally supported by four microtubule roots with a distinctive pattern. Flagella pulls the cell towards itself during displacement.
zoospora with a single stromopile flagellum
zoospora opistonta
For example, chytridiomycetes have haploid gametotalos and reversibly diploid sporothales. Gametotalos produces mobile gametes that fuse in between to form a double-flagged zygote that encysts. Upon germination, it produces a sporothal. It will develop two types of zoos: Mitosporangios and Myosporangios.
Mitosporangios produce diploid zoospores by mitoid division and zoospores give rise to new diploid spores.
Meiosis is produced by meiosis, haploid zoospores. Spores germinate to form haploid gametotalos.
zoospora anisocotta
For example, the life cycle of Plasmodiophorida alternates between the soil and the root interior of the host plant. These are mobile secondary zoospores thanks to the presence of two flagella.
These zoospores act as isospores. When the zygote is formed, it infects a radical hair of the host. This initial cell divides repeatedly and forms a very small intracellular plasmodium.
In Plasmodium, by meiosis, a multitude of cysts are formed inside the cells. The cells leave the cyst and leave the cyst on the ground.
Each of the cysts germinates and gives rise to a monodal state, a primary zoospore, which actively seeks out other radical hairs. Once these are introduced, it forms a plasmodium that transforms into a sporocyst.
The sporocyst eventually gives rise to numerous spores, which are then released to the ground. New primary spores give rise to secondary zoospores which can now merge.
zoospora heterocona
An example of a life cycle involving anomalous cycloids are oomyces. Both sexual and asexual reproduction occurs in these organisms. Mycelial stages with alternating diploid sexual reproduction stages.
During asexual reproduction they produce Heterocota zoospores. Among these, the mastigonous flagellum is directed forward and the naked one is directed backwards.
The sexual reproduction stage is by ogamy. Sex spores, called ospores, to survive in an unfavorable environment.
zoospora with a single stromopile flagellum
The zoospores of the Hyphochyotriomycetes are distinguished by presenting an anterior flagellum with mastigonema. They become incontinent when their movement stops. Later they germinate giving place to a tello. This thallus will produce new zoospores.
nutrition
Zoospores do not feed, they get their energy from reserve substances supplied by the parent during their formation. The substances used as reserves are of different nature depending on the taxonomic group.
Reproduction
Zoospores do not reproduce themselves. Depending on the taxonomic group, they can be produced by meiosis or by mitosis. Zoospores can be haploid or diploid, sexual or asexual.
Asexual spores germinate directly. Sex spores act as sex gametes and must be fused to form a diploid zygote.
diseases
Zoospores are not an infectious stage, but a means of spreading organisms that may be pathogenic. Among diseases that can produce organisms that zoospores can have are:
zoospora opistonta
Chytidromycetes contain Opistochonta spores. These organisms produce diseases such as plant black wart and corn brown spot.
In animals, chytridiomycosis that affects amphibians has even led to the extinction of the species. This disease is caused by Batrachochytrium dendrobatidi and the zooxors of these pathogens occur in the sporangia during asexual reproduction.
zoospora anisocotta
Several species of Plasmodiophoromycota are economically important plant pathogens. Among the diseases that are caused are pulsatile mange or scab disease in cabbage root and potato. These are caused by Plasmodiophora brassicae , and underground Spongospora , respectively.
zoospora heterocona
Diseases caused by oomycetes include late blight of potatoes, mildew and sudden oak plant death.
In animals it causes aphanomycosis in river crabs, saprolegniosis in fish, dogs in horses, cats, and occasionally in humans. Zoospores are attracted by chemical signals from hosts, where they invade and then germinate.
zoospora with a single stromopile flagellum
Hypochirtiomycetes are a small group of saprobic pseudo-fungi or parasites. About fifty species contained in this class are known.
Pseudohongos are protists similar to fungi. There are few references to diseases caused by parasitic species of this group that pass on to their hosts.
