Class Tutorial B.Sc(Botany)Part-I Life cycle of Albugo

Dr. Devanand kumar Department of Botany B.N college, Patna University, Patna Life cycle of Albugo ➢Systematic position

▪ Kingdom-Mycota ▪ Division-Eumycota ▪ Class- ▪ Order-Albuginales ▪ Family- ▪ -Albugo Life cycle of Albugo

➢Habit and Habitat

▪ The only genus of family Albuginaceae. ▪ Represented by more than 25 . ▪ Attacks mostly crucifers like , mustard, , , etc. ▪ Survives in soil as oospores in crop debris. Life cycle of Albugo ➢Symptoms ▪ Albugo causes white disease because it appears shiny, white, smooth irregular patches (pustules) or blisters on the leaves stems and other aerial parts of the plants. ▪ Increse in size of the cells (Hypertrophy) and organs takes place leading to formation of large galls. ▪ Severe infection causes proliferation of lateral buds, discolouration of flowers, malformation of flowers etc Life cycle of Albugo Life cycle of Albugo • Albugo is a biotrophic or parasite . • Mycelium is branched non septate and intrcellular. • Buton shaped haustoria are present. • Sporingiophores are formed on lower side of epidermis. • Sporangiophores bear the sporangia which are in basipetal chain. • Uppermost sporangia is thick walled and does not germinate. It put the pressure on epidermis. Life cycle of Albugo • Sporangia are unicellular, multinucleate with smooth and thick walled. • Size of is 14x16 to 16-20µm and diameter is 15-21µm • Sporangia are attached in chain by gelatinous disc like tissue pad which dissolve in presence of moisture and sporangia become free from chain. • When these sporangia germinate directly by forming germ tube then called conidia but it is rare. • . Life cycle of Albugo • Sporangia are detached from mycelium and spread by air or water from one place to other place. • At the time of germination papilla formation takes place which later forms zoospores. • Zoospores are unicellular biflagellate and kidney shaped. • After release zoospore rest and lose their flagella and encyst. • Encysted zoospores later germinate and infect to host. • . Life cycle of Albugo Life cycle of Albugo • For formation and germination of sporangia optimum temperature is 10ºC. • Sexual reproduction takes place by oogamy. • Oogonium(female) is spherical, terminal or intercalary and have about 200 nucleus. Its protoplasm is divided in periplasm and ooplasm. • Antheridium( male) is club shaped and have 6-12 nucleus. • Oogonium and antheridium come in contact by a papilla which disappear shortly. Life cycle of Albugo • At the point of contact of oogonium cell wall become thin and form papilla. • Through the contact of both sex organs antheridium nucleus moves towards oogonium and later zygote form which is called oospore. Oospores are spherical, yellow to dark brown in colour and diameter is 40-55µm and its cell wall is thick and tuberculate. • Before germination of these spores need a resting period so called “Resting spores” • . Life cycle of Albugo Life cycle of Albugo • After resting period these oospores germinate by forming sessile vesicle which produce zoospores. References

• www.biologydiscussion.com/fungi.

• www.slm.ignou.com/biology.