The pciniaresentation describe the life cycle of Pythium, Albugo, Erysiphae, Claviceps, Ustilago, Puccinia. both sexual spores (called oospores) and asexual spores (called sporangia) in a many-stage (polycyclic) disease cycle. infection stag heads oospore productt0n zoo spores. \. SEXUAL c germ1not1~. Oospores -overwintering spores. 8. Figure 8. Life cycle of Albugo candlda.

Author: Zulunris Tojatilar
Country: Bosnia & Herzegovina
Language: English (Spanish)
Genre: Medical
Published (Last): 19 January 2005
Pages: 73
PDF File Size: 1.41 Mb
ePub File Size: 15.47 Mb
ISBN: 307-2-99164-551-6
Downloads: 44567
Price: Free* [*Free Regsitration Required]
Uploader: JoJoll

The latter ,ife splits into two halves so that the subsequent proliferation of sporangiophore involves the exposed half septum. Within the plasma membrane of the haustorium lomasomes are more numerous than in the intercellular hyphae. In Albugo each successive sporangium is cyycle of seceding from the sporangiophore or from the young sporangium.

Sometimes the oogonium is intercalary in position. It is an elongated club-shaped cell A. These hyphae produce, at right angles to the epidermis are short, thick walled, un-branched and club shaped.

The asexual reproduction takes place by means of biflagellate zoospores formed inside the sporangia. Severe infection causes proliferation of the lateral buds, discoloration of flowers, malformation of floral parts and sterile gynoecium.

Prior to this a spherical and granular cytoplasmic body appears in the centre of the oosphere H. The hyphal wall contains cellulose and not chitin.

The outer layer is thick, warty or ljfe and represents the exospore. There are some resistant and partially resistant varieties which are necessary in landscapes where white rust is present.


Management includes use of resistant cultivarsproper irrigation practices, crop cycllesanitation, and chemical control. Symptoms of white rust caused by Albugo typically include yellow lesions on the upper leaf surface and white pustules on the underside of the leaf. However, the ooplasm at maturity has a single centrally located nucleus G.


A papilla is developed on one side which later burst and liberates the zoospores. As the second sporangium increases in size it pushes the first upward without disjunction. His interpretation was disputed by later workers. Fields should be inspected every 7—14 days to remove additional material and monitor spread. A portion of the contents of the oogonium surrounded by a thin membrane grows into a papilla-like outgrowth G.

Here’s how it works: They are terminal in position, however, intercalary oogonia also occur, though rarely. Biological Specialization or Physiological Specialization 6.

With light microscope the haustorium is seen as a small, spherical structure consisting of two parts namely: Most of the original cytoplasm of the oogonium forms the central,rounded dense ooplasm. Each part later on rounds up and metamorphoses into zoospore Fig. It persists only up to the time of fertilization. They held that Albugo and other Oomycetes, as a whole, are haploid. It carries a single male nucleus. This organism causes white rust or white blister diseases in above-ground plant tissues.

Later the vacuoles disappear and the multinucleate protoplast undergo division. Thereafter the fertilisation tube collapes but persists and the coenocentrum vanishes.

Albugo: Habitat, Symptoms and Reproduction | Mastigomycotina

This view is gaining ground. The hyphae live and ramify in the intercellular spaces of the susceptible host tissue. Albugo is one of three genera currently described in the family Albuginaceaethe taxonomy of many species is still in flux.

The oldest sporangia have none.

Albugo: Habitat, Symptoms and Reproduction | Mastigomycotina

The end of the male hypha enlarges into club-shaped swelling. After penetration the first haustorium originates near the tip of the young hypha.

  DIN EN 378-1 PDF

On the onset of conditions favourable for growth, the oospore germinates. It has a disc-like contractile vacuole on one side and is furnished with two flagella, one short and liife long. These zoospores then swim in a film of water to a suitable site and each one produces a germ tube – like that of the sporangium – that penetrates the stoma.

Albugo candida Albugo capparidis Albugo capparis Albugo caryophyllacearum Albugo chardoni Albugo evolvuli Albugo gomphrenae Albugo hesleri Albugo hohenheimia Albugo ipomoeae-panduratae Albugo albjgo Albugo leimonios Albugo lepidii Albugo lepigoni Albugo mauginii Albugo occidentalis Albugo resedae Albugo rorippae Albugo trianthemae Albugo tropica.

It is aobugo as the coenocentrum. The oogonium develops a papilla like out growth at the point of contact with the antheridium. In the very beginning the hyphae accumulate just beneath the epidermis of the infected leaf. Stevens suggested that Albugo possesses diploid somatic nuclei which undergo meiosis in the gametangia antheridia and oogonia. The oospores are perennating bodies and survive in adverse conditions.

After the organization, all the nuclei of the ooplasm, except one, migrate to the periplasm forming a ring and undergo second mitotic division. They are produced on the sporangiophores. Sometime after all the nuclei of ooplasm migrate into the periplasm D and become arranged in a ring. The shorter flagellum is of tinsel type and the longer one of whiplash type.