In this article we will discuss about the asexual and sexual reproductive structure of pythium.
Asexual Reproduction of Pythium:
1. It takes place by means of zoospores formed in small, globular or oval, multinucleate zoosporangia.
2. A zoosporangium is present singly and terminally (Fig. 61A) or intercalary (Fig. 61B) on the sporangiophore and remains separated from rest of the thallus by a septum.
3. A narrow papillate outgrowth is given out by the apical portion of a zoosporangium (Fig 60D).
4. A thin balloon-shaped vesicle is formed by the apex of this outgrowth, and many uninucleate daughter protoplasts of the zoosporangium migrate into it (Fig.61).
5. Each uninucleate protoplast in the vesicle metamorphoses into a reniform, biflagellate zoospore. Both the flagella are laterally attached. Zoospore germinates by producing the germ tube.
6. Asexual reproduction also takes place by gemmae or by thick-walled chlamydospores.
Sexual Reproduction of Pythium:
1. Sexual reproduction is oogamous and takes place by antheridium and oogonium. Both the sex organs develop near each other showing the homothallic nature (Fig. 62).
2. Oogonium develops at the tip of oogonial branch as a globular, multinucleate structure, which later on separates from rest of the part by a septum. Mature oogonium differentiates into outer peripheral periplasm, and central granular and dense ooplasm.
3. All the nuclei of multinucleate ooplasm, except one, pass into the periplasm and degenerate. Thus ooplasm remains uninucleate.
4. The male reproductive body, arises as an elongated, club-shaped and multinucleate structure, the tip portion of which separates from rest of the hypha and called antheridium. Many uninucleate male gametes are formed.
5. A fertilization tube (Fig. 62) is formed by the antheridium at the place of its contact with oogonium. Male gamete fuses with the female gamete or egg through this tube and thus oospore develops.
6. Thick-walled oospore remains surrounded by outer exine and inner intine, and germinates by producing a germ tube, prior to which the diploid nucleus divides into many nuclei, which change into zoospores.