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melampsora
- 2. Introduction Melampsora belongs to family Melampsoraceae which are characterised by formation of sessile teliospores which are united laterally and forming crusts or columns on the host. Important genera are melampsora, cronartium, urediniopsis, coleopsorium. Melampsora contains 80 species and most of them are heterocious. Out of them 20 species known from India (Bilgrami et al., 1979) Melampsora lini is most important one
- 3. The disease is of great importance bcz it was with this host pathogen system that H.H.FLOR (1955) Gave gene for gene concept of disease resistance in linseed rust caused by Melampsora lini Contd…
- 4. Economic importance Melampsora lini cause linseed rust prevalent in all countries The disease causes reduction in seed yield and oil content Occurs in America , Canada , Europe , South america , Africa , Australia , India 80 % of loss in yield has been estimated in our country every year
- 5. Kingdom: Fungi Phylum : Basidiomycota Class: Urediniomycetes Subclass: Teliomycetidae Order: Uredinales Family: Melampsoraceae Genus: Melampsora Taxonomic position
- 6. Order: Uredinales Family:Pucciniaceae teleutospores are stalked and free Uromyces fabae one cell Phragmedium more than two Puccinia two cells Puccinia graminis *uredospores,unicellular,binucleate double wall and cup shaped. *teleutospore,bicellular,binucleate haploid then converted to uninucleate diploid after karyogamy the apex of the spore is pointed. . Puccinia allii *uredospore,unicellular, binucleate, double wall and globose. teleutospore,binucleate, bicellulae,haploid then converted to diploid after karyogamy the apex of the spore is flattend. Family:Melampsoracae teleutospores are sessile and united together Melampsora Lini
- 7. General characters of Melampsora It consists obligate biotrophes It gain entry through stomatal cells or by direct penetration of epidermal cells After entry primary and secondary mycelia grows intercellularly giving rise to haustoria Produces single celled, sessile teliospores with a brown membrane , compacted into flat , dark coloured groups produced either below the cuticle or epidermis Urediniospores are intermixed with capitate paraphyces and are produced in erumpent uredinia.
- 8. Produce all 5 stages • Stage 0 Spermagonia bearing spermatia(n) and receptive hyphae(n) • Stage 1 Aecia bearing aeciospores(n+n) • Stage 2 Uredinia bearing uredinospores(n+n) • Stage 3 Telia bearing teliospores (n+n→2n) • Stage 4 Basidia bearing basidiospores(n)
- 9. Uredial stage Uredia occurs on both surface of the leaves and aerial parts of plants. Uredospores are orange colour , ovate , 15-25 x 13-18 micron size and are echinulated Capitate paraphyces are found abundunt in uredisori Under favourable condition uredospores germinate within an hour causing infection of the host
- 10. Telial stage Teliospores are formed in teleutosori found commonly on the stems. Teliospores are sessile , cylindrical , single celled and measure 46-80 x 8-20 micron size Reddish brown colour , elongated , subepidermal forming solid crust on the stems. Teliospores germinate readily bcz they do not have dormancy period
- 12. Pycnial stage Pycnia and aecia were not observed in india untill 1940. Prasad (1940) obtained their formation on plants in experiemental cultures at shimla Pycnia are pale, yellow, flask shaped and subepidermal on leaf & stem Pycniospores are minute and oval to globose in shape. Aecial stage The aecia are orange yellow that are scattered on under surface of leaf and sometimes on stems. Aeciospores are polygonal in shape 17-27micron in diameter.
- 13. Life cycle of Melampsora lini
- 15. Puccinia • Teliospores stalked • Teliospores are bicelled • Teliospores are free from each other • Capitate paraphyces absent • Includes 3000 sp. As reported Melampsora • Teliospores are sessile • Single celled • Teloispores are in coloumn touching one another laterally • Present • More than 74 sp. reported
- 16. Plant resistant or tolerant clones, where available. Removing and destroying diseased leaves from the ground may help reduce infections. Wide spacing between trees may create a less favorable microclimate for spread and infection. Chemical controls are ususally not warranted. Management
Hinweis der Redaktion
- The gene-for-gene relationship was discovered by the late Harold Henry Flor[1][2][3][4] who was working with rust (Melampsora lini) of flax (Linum usitatissimum). Flor showed that the inheritance of both resistance in the host and parasite ability to cause disease is controlled by pairs of matching genes. One is a plant gene called the resistance (R) gene. The other is a parasite gene called the avirulence (Avr) gene. Plants producing a specific R gene product are resistant towards a pathogen that produces the corresponding Avr gene product.[5] Gene-for-gene relationships are a widespread and very important aspect of plant disease resistance.