Synchytrium is a genus of fungi in the order Chytridiales. It is an obligate biotrophic parasite that infects over 120 species of angiosperms. It has both asexual and sexual life cycles. Asexually, resting spores germinate and release zoospores that infect host cells. The zoospores form sporangia inside host tissue. Sexually, zoospores fuse to form zygotes, which develop into thick-walled resting spores. One notable species is S. endobioticum, which causes potato wart disease and forms galls on potato leaves. Over 80 Synchytrium species have been reported in India, infecting

1. SYNCHYTRIUM SP.
MEMBER OF CHYTRIDIALES
BY
SOURADEEP 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 Obligate parasite
During spring and late
winter the temperature is
not above 8⁰ C and enough
moisture in the
atmosphere allows the
resting spore (Winter
sporangia) to germinate in
zoospores
When the temperature rises
above 12-15⁰ C the zoospores
immediately enters the hosts
and encyst themselves forming
the Summer sporangia, with
very short lifespan and quick
reproduction
When the environment is
stressed i.e. lack of enough
moisture, the zoospores fuse
together to form zygote and
then it again matures to form
the Winter sporangia

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

9. 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

10. 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

11. 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

13. REFERENCES:
• Webster, J., & Weber, R. W. S. (2007). Introduction to fungi 3 ed.