Ustilago

Ustilago:-

Classification:-

        Kingdom - Myceteae

        Division - Amastigomycota

        Sub-division - Basidiomycotina

        Class - Basidiomycetes

Sub-class - Teliomycetidae

        Order - Ustilaginales

        Family - Ustilaginaceae

        Genus - Ustilago

Common Names:- Smut fungi

Order - Ustilaginaceae:-

> All the members of this order are called Smut fungi.

> Haustoria are absent in the members of this order.

> Members of this order are monogenetic, that is, they complete their life cycle on only one host.

> In all members of this, 2 types of spore stages are found –

i. Teleutospores or Ustospores

ii. Basidiospores

> Basidiospores are produced directly on the basidium i.e., sterigma is absent.

Important Species:- 

i. U. nuda tritici:- Loose smut of Wheat

ii. U. nuda:- Loose smut of Barley

ii. U. avenae:- Loose smut of Oats

iii. U. hordei:- Covered smut of Barley

iv. U. kolleri:- Covered smut of Oats

v. U. maydis:- Smut of maize

Habit and Habitat:-

- It is a facultative saprophyte.

- It spreads smut disease on cereals like wheat, barley, maize, oats etc.

- It can also grow on rotten leaves, garbage and manure piles etc.

Thallus structure:-

- Simple pore septate and unicellular hyphae.

- Cells are monokaryotic in primary mycelium and dikaryotic in secondary mycelium.

- Branched mycelium.

Reproduction or Life cycle:- 

i. Teleutospores:- 

ii. Basidiospores / Infection threads:-

Methods of Dikaryotization:-

a. By somatogamy:- The secondary mycelium is formed by somatogamy from the primary mycelium.

b. By contact between Basidiospores:- 

i. Direct fusion:- Eg. - U. violacea

ii. Germ tube fusion:- Eg. - U. nuda tritici

c. By contact between infection threads:- In some species basidiospores are not formed at all. Rather infection threads are formed. Eg. - U. nuda tritici