Synchitrium

a quick and informative revising slide for Synchytrium sp

1. Synchytrium sp. Member of Chytridiales B y S ouradeep Banerjee, M.Sc Lecturer, Dept of Botany J.K.College

2. Introduction: Belongs to the order Chytridiales , almost >50% of chytrids identified till dates are under this order Sparrow, 1973, classified chytridiales on the basis of thallus morphology D.J.S.Barr , 2001, pointed this classification as unsatisfactory, as it was observed that same genus can show different morphology under in vivo and in vitro conditions Future classification is based on zoospore ultra structure and comparison of DNA and 18s rRNA

3. Synchytrium Classification: Kingdom : Fungi; Class : Chytridiomycetes ; Order : Chytridiales ; Family : Synchitriaceae Endobiotic, holocarpic During reproduction may become converted to sorus (group of sporangia) or prosorus Zoospores similar as those of chytrids Sexual reproduction: - Isogamy and forms resting spores 120 sp. biotropic parasite of angiosperm Some with narrow range of host e.g. S. endobioticum only on Solanaceae, S. macrosporium on huge range of organisms

4. Reports In INdia Almost over 80 sp. Reported in INDIA S. rytzii on lamiaceae S.trichosanthoidis and S.laginariae on Cucurbitaceae S.taraxicola on Taraxacum officinale S.sisamecola on Sesamum indicum S.endobioticum on potato In INDIA the disease was first reported in Rangbul , Darjeeling in 1953

5. Synchytrium endobioticum Causes potato wart Biotropic parasite, hard to culture invitro Mainly infects and are active in cold humid climate Galls form on leaf tissue, causing convolution of leaf Though infection of this fungi can cause huge loss of yield, thanks to the breeder and geneticist out there as they have produce many disease resistant variety of potato

6. ecology

7. Life Cycle ASEXUAL Resting spore: Spherical, thick walled, dark brown wall folded in convolutions Hosts have resting spores present within them Gets released by decay of warts and may remain alive for around 40 years in soil The exospore bursts out by an irregular aperture and the endospores balloons forms a vesicle within which a single sporangium differentiates. Thus the resting spore acts as a prosporangium The chitin and the branched chain waxed esters are degraded inside the snails digestive system

8. Zoospore: Germinate same as a holocarpic chytrid do Capable of swimming in soil water for >2hrs It bound to either the eyespot of tuber of potato causing the dormant eye to sprout Gradually a small fungal thallus starts growing inside causing a rosette shaped cells surrounding a single infected central cell Thick and dark brown coloured cell wall The thallus of fungi settle down at the bottom of the cell and covers itself up by chitinous covering, now it is known as prosorus or Summer spore Gradually this prosorus covers the upper half of the cell by protrusion from inside The cytoplasmic content and the nuclei of the prosorus gets transferred into the protrusion and may mitotically divide upto 32 cells. At this stage the cytoplasmic content of the prosorus divides into 4-9 sporangia forming a Sorus the division continues and accordingly each nucleus gets covered by a amount of cytoplasm gradually forming zoospores and releasing them by absorbing water

9. SEXUAL Alternatively the zoospores may fuse together as gametes They are flagellate and may swim and then fuse, and due to being of same morphology this is known as isogamy Curtis (1921) suggested that the zoospores will not fuse when coming from same sporangia Kohler (1956) said that at first the zoospores are not mature enough and later on they are capable of getting fuse together The maturation of zoospore may take place within or outside the sporangium At first the zoospores are motile and male later on it become quiescent (female) The zygote after forming encyst itself in the host epidermis and penetrates similar as zoospores Zygote infection causes hyperplasia, ultimately causing warts Zygote now encapsulate itself by a two layered thick wall forming ridges and golden brown forming spines on the outside. The inner wall is hyaline layered covering the granular cytoplasm

10. This zygote now gradually forms the resting spore Before the resting spore starts producing zoospores it undergoes meiosis So the diploid bodies are the zygote and the young resting spore Where the zoospores, mature resting spore and the prosorus are all haploid in nature

11. References: Webster, J., & Weber, R. W. S. (2007). Introduction to fungi 3 ed.