Types of Asexual Reproduction- Multiple Fission, Budding , Spore Formation

 

Asexual Reproduction & its types

Definition  of asexual reproduction and its Ist types i.e Binary fission has been discussed in earlier post so, now we are discussing about the other three types of asexual reproduction which are- Multiple fission, Budding and Spore formation.

MULTIPLE FISSION

Multiple fission is the division of the parent into many small daughter individuals simultaneously.

                                      

Example 1- Multiple fission in plasmodium

              

   In Plasmodium ( a malarial parasite), multiple fission takes place in the active adult(schizont) as well as in the encysted zygote(sporont). The process is known as the schizogony in the former case and is termed as sporogony.The daughter individuals are called merozoites in the former case and sporozoites in the latter case. 

Example 2- Multiple fission in Amoeba

              The products of multiple fission become individually surrounded by resistant coats, the cyst walls, before their release from the parent, the multiple fission is here called sporulation, and the encysted products are termed as spores.The spore remain inactive during unfavourable conditions such as desiccation and extremes of temperature. On the return of favourable conditions, each cyst hatches into a small Amoeba, which gradually grows into an adult. Sporulation not only brings about the  multiplication, but also enables the organisms to (i) survive  during unfavourable condition, and (ii) disperse to new localities with air.

Budding 

         Formation of a daughter individual from a small projection , the bud, arising on the body is called budding.

Example 1 - Budding in YEAST

         Yeast is the unicellular fungi. It produces asexuallyby the formation of spores. During the process of budding in yeast, the parent cell develops  a small protuberance which grows in size. The parent nucleus divides and one of the two daughter nuclei goes into bud. Finally the bud get detached and grows into new individual.

Example 2 - Budding in HYDRA

          In Hydra, the buds arise from the surface of the  parents body. Each bud grows and gradually assumes the form ans size of the parent. When full- grown , the new individual may separate from parent and become an independent animal.

SPORE FORMATION

Spores are the propagules which  germinate to produce new individuals. There are several kinds of spores Some of them are given below:

Zoospores:- The zoospores are special kind of motile and flagellated spores produced inside the sporangia .They are usually naked(without cell wall). The flagella help them to swim in aquatic habitat for proper dispersal. The Reproduction by zoospores occurs in some lower fungi- phycomycetes(e.g Achlya, Albugo, Phytophthora,etc.)

Sporangiospores:- These are non- motile spores produced inside the sporangia, Sometimes these spores are also known as endospores.They are usually dispersed by wind and germinate to produce new mycelium (e.g Rhizopus, Mucor, etc.)

Chlamydospores:- These are thick walled resting  spores produced directly from hyphal cells. They store reserve food material and  are capable of withstanding long unfavourable conditions.

Oidia:- The breaks up into its component cells or small pieces which behave like spores.They are thin walled and do not store food material. The oidia are usually formed under the conditions of excess water,sugar and certain salts. They germinate immediately after liberation and cannot survive under unfavourable conditions.

Conidia:- These are non- motile spores produced singly or in chains by constriction at the tip or lateral side o special hyphal branches called conidiophores.They are produced exogenously, dispersed by wind and germinate directly by giving out germ tubes.