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
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.
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
11.
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.
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
Editor's Notes
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.
