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DOWMY MILDEW FUNGI part 01.pptx
- 1. ANNAMALAI UNIVERSITY FACULTY OF AGRICULTURE DEPARTMENT OF PLANT PATHOLOGY PAT-501 MYCOLOGY GENERAL CHARACTERS AND LIFE CYCLE OF GENUS PERONOSPORA , PSEUDOPERONOSPORA, PLASMOPARA , BREMIA , SCLEROSPORA , PERONOSCLEROSPORA BY R.LOKESH I -M.sc.,Agriculture Plant pathology Annamalai university TOPIC: Part-1
- 3. DOWNY MILDEW FUNGI 1. Downy mildew of Pearlmillet Sclerospora graminicola (Green Ear disease) 2. Downy mildew of Sorghum Peronosclerospora sorghi (Leaf shredding disease) 3. Downy mildew of Maize Sclerophthora rayssiae (Crazy top disease) 4. Downy mildew of Grapevine Plasmopara viticola 5. Downy mildew of Cucurbits Pseudoperonospora cubensis 6. Downy mildew of Tobacco Peronospora tabacina (Blue mould disease) 7. Downy mildew of Onion Peronospora destructor 8. Downy mildew of Lettuce Bremia lactucae
- 5. KINGDOM: CHROMISTA/STRAMENOPILES • Have uni- or multicellular somatic phase with absorptive type of nutrition. • Cell wall rich in cellulose and synthesize amino acid by a, ẞ aminopimelic acid lysine biosynthetic pathway. • The asexual spore is biflagellate zoospore with posteriorly oriented whiplash and anteriorly oriented tinsel flagella (heterokont). • Zoospores have tubular mitochondrial cristae, perioxisomes and Golgi bodies.
- 6. PHYLUM: OOMYCOTA / PSEUDOFUNGI /EGG FUNGI (Heterokonts) /zoosporic fungi • They are unicellular and holocarpic or eucarpic filamentous species. The filamentous species have profusely branched, hyaline and coenocytic hyphae. • Cell wall primarily made up of B-glucans but also contain amino acid, hydroxyproline as well as small amounts of cellulose. • Form diploid thallus and meiosis occurs in the developing gametangia Le. the assimilative phase is diploid. • Zoospores are biflagellate, having one short posterior whiplash and another long anterior tinsel flagellum. Many oomycetes produce one kind of zoospores (monoplanetic) and some produce (Saprolegnia) diplanet zoospores. • Sexual reproduction is oogamous by gametangial contact of club shaped antheridium(male) and globular oogonium(female).
- 7. Order: Peronosporales (Higher form of Peronosporomycetidae) • Members are obligate parasites of higher plants with well branched, coenocytic intercellular mycelium, which enter the host cell through knob like (Albugo) or elongated or branched haustorium. • Asexual reproduction takes place by means of sporangiospores produced inside sporangia. Sporangiophores are strikingly different from the vegetative hyphae and bear sporangia singly (Peronosporaceae) or in chains (Albuginaceae). • Zoosporangia germination mostly depends upon temperature. They mosty germinate by producing zoospores but in some they germinate directly and produce germ tube. Zoospores are kidney shaped monoplanetic and laterally biflagellate with whiplash and tinsel type flagella.
- 8. Order: Peronosporales (Higher form of Peronosporomycetidae) • Members are obligate parasites of higher plants with well branched, coenocytic intercellular mycelium, which enter the host cell through knob like (Albugo) or elongated or branched haustorium. • Asexual reproduction takes place by means of sporangiospores produced inside sporangia. Sporangiophores are strikingly different from the vegetative hyphae and bear sporangia singly (Peronosporaceae) or in chains (Albuginaceae). • Zoosporangia germination mostly depends upon temperature. They mosty germinate by producing zoospores but in some they germinate directly and produce germ tube. Zoospores are kidney shaped monoplanetic and laterally biflagellate with whiplash and tinsel type flagella.
- 9. • Sexual reproduction is oogamous. Oospore wall is hyaline or brownish and smooth (Peronosporaceae) or ornamented (Albuginaceae). • Oospore germinates either by a germ tube (Peronosporaceae) or by theproduction of large number of zoospores (Albuginaceae).
- 11. Family: Peronosporaceae (Downy mildew fungi) • Members of this family cause "downy mildews" disease in dicots, which etymologically means "hairy fungi" as the sporangiophores look like hairs on the lower surface . • Produce sporangia singly or in chains at the tip of branched sporangiophore. • Sporangia germinate directly i.e conidial type of germination. • The membersof the Peronosporaceae are differentiated chiefly by the branching of their sporangiophores. • The sporangia are wind dispersed and germinate in water films on plant surface to release zoospores. • The sporangia of the genus Peronospora germinate directly into the germ tube.Fundamentals of Phytopathology. • Produce smooth walled oospores. • The Peronosporaceae currently includes downy mildews, Halo phytophthora. Phytophthora and Phytopythium
- 12. DOWNY MILDEW FUNGI • It is the most highly specialized family of the order Peronosporales. • Members of this family are causing "downy mildews" disease in dicots, which etymologically means "hairy fungi", as the sporangiophores look like hairs on the lower surface. • The members of the Peronosporaceae are differentiated chiefly by the branching of their sporangiophores.
- 13. DOWNY MILDEW GENERA • Bremia • Peronospora • Plasmopara • Pseudoperonospora • PerenoSclerospora • Sclerospora
- 17. General Characters of Peronospora • Peronospora was first described in 1837 by August Carl Joseph Corda, a Czech mycologist and physician, in his first of six volumes of his Icones fungorum hucusque cognitorum. • Peronospora is a genus of oomycetes that are obligate plant pathogens of many eudicots. • Most species in this group produce a downy mildew disease, which can cause severe damage to many different cultivated crops, as well as wild and ornamental plants. • Peronospora has far more species than any other genus of the downy mildews. • However, many species have been moved from this genus to be reclassified to other or new genera. • Among these was the most famous Peronospora species, formerly known as Peronospora parasitica, and now known as Hyaloperonospora parasitica. • Now, the Peronospora species of most importance is likely the Peronospora tabacina. • Peronospora tabacina causes blue mold on tobacco plants and can severely reduce yields of this economically important crop to the point where it has been classified as a bioweapon.
- 18. General Characters of Peronospora • Peronospora was first described in 1837 by August Carl Joseph Corda, a Czech mycologist and physician, in his first of six volumes of his Icones fungorum hucusque cognitorum. • Peronospora is a genus of oomycetes that are obligate plant pathogens of many eudicots. • Most species in this group produce a downy mildew disease, which can cause severe damage to many different cultivated crops, as well as wild and ornamental plants. • Peronospora has far more species than any other genus of the downy mildews. • However, many species have been moved from this genus to be reclassified to other or new genera. • Among these was the most famous Peronospora species, formerly known as Peronospora parasitica, and now known as Hyaloperonospora parasitica. • Now, the Peronospora species of most importance is likely the Peronospora tabacina. • Peronospora tabacina causes blue mold on tobacco plants and can severely reduce yields of this economically important crop to the point where it has been classified as a bioweapon. BLUE MOLD ON TOBACCO Peronospora parasitica
- 19. Disease cycle of Peronospora tabacina
- 20. GENERAL CHARACTERS OF PSEUDOPERONOSPORA • Pseudoperonospora cubensis is a species of water mould known for causing downy mildew on cucurbits such as cantaloupe, cucumber, pumpkin, squash and watermelon. • Berkeley and Curtis first reported the disease in Cuba in 1868. • The pathogen causes angular chlorotic lesions on the foliage. • The disease is sometimes called wildfire because of how rapidly it progresses, as if the crop were burned by fire. • Pseudoperonospora cubensis is an obligate parasite or biotroph, meaning that it requires live host tissue in order to survive and reproduce.
- 21. Scientific classification Kingdom: Chromista Phylum: Oomycota Order: Peronosporales Family: Peronosporaceae Genus: Pseudoperonospor a Species: P. cubensis Binomial name Pseudoperonospora cubensis (Berk. & M.A. Curtis) Rostovzev DOWNY MILDEW ON CUCURBITS
- 22. SYMPTOMS ON Cucumber, squash and pumpkin • Symptoms on cucumber and squash are angular lesions that are limited by the leaf veins. • During periods of leaf wetness from dew, irrigation or rainfall, incipient lesions can become conspicuously water-soaked (Figure 1). • This is the earliest symptom produced by the disease, but will disappear as moisture dissipates. • Early lesions are light green in appearance (Figures 2 and 3) and become chlorotic and finally necrotic as host plant cells die (Figure 4). FIGURE 1 FIGURE 2 FIGURE 3 FIGURE 4
- 23. • Severe infection results in leaves that are completely dead and curled up. This symptom has been described as “wildfire” as the leaves appear to be burned (Figure 5).
- 29. REFERENCES • https://plantlet.org/oomycetes-order-peronosporales/ • https://en.wikipedia.org/wiki/Pseudoperonospora_cubensis • https://www.apsnet.org/edcenter/disandpath/oomycete/pdlessons/ Pages/Cucurbits.aspx • An Introduction to Fungi- H.C.Dube