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1. Synchytrium • Synchytrium is a large genus of plant pathogens within the phylum Chytridiomycota. Species are commonly known as false rust or wart disease. • Classification: Kingdom: Fungi; Class: Chytridiomycetes; Order: Chytridiales; Family:Synchitriaceae

2. Features • 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

3. Vegetative Structure of Synchytrium: • The vegetative body of Synchytrium consists of minute endobiotic holocarpic thallus, represented by naked uniflagellate zoospore with whiplash flagellum.

4. Reproduction 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

5. 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

6. Contd. • 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

7. 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

8. QS:

9. QS:Synchytrium endobioticum • Synchytrium endobioticum is a chytrid fungus that causes the potato wart disease, or black scab.[1] It also infects some other plants of the genus Solanum, though potato is the only cultivated host • Characteristices: • Unicellular thallus body • The thallus is endobiotic and holocarpic • Monocentric thallus body • At reproduction the thallus body may be converted directly into a group (or sorus) of sporangia • Sexual reproduction is by junction of isogametes,resulting in the formation of thick walled resting sporangia

10. QS:Potato wart Stmptoms • Usually the disease affects the underground parts of the host. • Diseased potato tubers appear as brown or black cauliflower like outgrowths. • The fungus cause the enlargement of the surface cells (hypertrophy) as well as increased the numbers of cells (hyperplasia) in the infected potato tuber, converting them into useless masses of watery tissue. • Most of the host cells contain resting sporangia. • Galls or tumors may be formed on aerial parts (stems and leaves)

11. QS:Economic importance • The most well-known species is Synchytrium endobioticum, a parasite of Solanaceae; it is the causal agent of black wart in potatoes. • Synchytrium anemones can cause harm to anemone and thalictrum flowers. Synchytrium aureum infects many agricultural and horticultural plants. • Synchytrium vaccinii creates galls on cranberry, azalea, chamaedaphne, gaultheira, and ledum. Synchytrium fragariae infects strawberry plants. • Synchytrium psophocarpi is one of the major diseases affecting winged bean (Psophocarpus tetragonolobus), which is important high protein crop. • Synchytrium solstitiale parasitizes the yellow star thistle (Centaurea solstitialis), an important weed in the United States. For this reason, S. solstitiale is being considered as a biological control of the yellow star thistle in the United States. • Another species being considered for biological control use is Synchytrium minutum, which occasionally parasitizes kudzu. However, S. minutum parasitizes cultivated kudzu patches more often wild patches and has also been reported from agricultural crops.