Life Cycle of phytophthora infestans

Answer 1

Long story short- Zoospores are released from sporangia. Zoospores swim and then encyst. Penetrate the host cell and then sexual reproduction take place between andthredium and oogonium (P. infestans is hetrothallic). zoospore is produced which give rise to new thalli.

P. infestans are sympodially branched and bear lemon shaped, papillated sporangia at their tips. Production and germination of sporangia depends upon the relative humadity of the environment. They are formed at relative humidity of 91-100% and at temperature range of 2-20 degree celcius.

The zoospores are released from the tip of the sporangia, they swim in the film of water, encysts on the host surface and germinates by means of a germ tube which penetrates the host epidermal cell or enter the cell through stomata.

It is a hetrothallic fungus, that is sexual reproduction take place by means of anthredia and oogonia of opposite mating type. The oogonia penetrate and grow through the anthredium developing a globolus structure above the anthredium. Migration of single anthredium in the oogonium take place through oogonial cell wall but fusion is delayed until oospore wall is matured. after a perios, Zoospore developed in sporangium give rise to new thalli.