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

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

▪ Kingdom-Mycota ▪ Division-Eumycota ▪ Class- ▪ Order- ▪ Family- ▪ -Synchytrium Life cycle of Synchytrium ➢Habit and habitat- ▪ Synchytrium includes about 200 . ▪ Wildly distributed through out the world. ▪ Most species are parasite on growing in cool and moist climate. ▪ is a serious parasite of tubers causing black wart disease. ▪ Black wart diseae of potato was first repoted in 1895 from Hungary. ▪ In India, it was first reported by Ganguly and Paul(1953) from Darjeeling. Life cycle of Synchytrium ➢Vegetative body- ▪ The thallus is unicellular, endobiotic and holocarpic and represented by a nacked posteriorly uniflagellate zoospore. ➢Sympotoms- ▪ Usually the disease affects the underground parts of host except roots i.e. tubers, buds of stem and stolen. ▪ The disease appears as warty, tuberous and dirty cauliflower like outgrowths on infected parts Life cycle of Synchytrium • Warts are even larger than the tubers covering the whole tuber. • Warts varry in size and colour from greenish white to cream and black depending upon the exposure of light. • Galls and tumor may be formed on aerial parts as well. Life cycle of Synchytrium • According to British mycologist, K.M. Curtis, a zoospore comes to rest on the epidermis of the host, make a minute pore on the epidermal wall and penetrates leaving its outside. • Formation of thick walled and rounded summer spore called prosorus or summer sporangia within the host takes place. • Prosorus matures and germinates and its nucleus undergoes repeated till 32 nuclear stage. Life cycle of Synchytrium • Further cleavage of cytoplasmic content of prosorus into a number of multinucleate segments forming a sorus. • The no of segments in a sorus varries from 4 to 9 where repeated nuclear division takes place untill 200 to 3oo nuclei are formed. • Depending on the environmental condition i.e if abundant water is available(Summer) each sorus behaves either as or summer sporangia or zoosporangia that produces zoospores and gametangia during water shortage(winter) that produces motile gametes Life cycle of Synchytrium Life cycle of Synchytrium • Asexual reproduction occurs during humid weather when water is available. The prosoral segment behaves as a summer sporangia or zoosporangia. • The sporangia swell in presence of water and brust open by a small pore through which the zoospores escape. • These zoospores swim in a film of water and initiate a series of host infection. • Sexual reproduction occurs in unfavourable condition during dry weather in winter. Life cycle of Synchytrium • During drought condition, the sorus behaves as a gametangia. Gamatangia produces motile uniflagellate isogamates (Planogamates). • Planogamates are smaller than the zoospore. • Isogamous copulation occurs in a film of water or on surface of host or in soil. • Plasmogamy follows karyogamy and biflagellate zygote(2n) is formed, zygote penetrates the host and transform in resting sporangia or winter sporangia and remain dormant till the return of spring season. Life cycle of Synchytrium • During spring, the nucleus(2n) of resting sporangia undergoes and divide further repeatedly by mitosis and produces numerous uniflagellate zoospores(n) and ready for new infection to host cell. • These zoospores are larger than the zoospores produced from summer sporangia. Life cycle of Synchytrium Reference • www.slm.ignou.com/biology • www.biologydiscussion.com/fungi