Question

Uredospores is formed by Puccinia on
(a)Wheat
(b)Barberry
(c)Both (a) and (b)
(d)Dalbergia and Wheat

Answer 1

Puccinia graminis causes black stem rust. Puccinia is a heteroecious form; its life cycle is completed in two different hosts. Their dikaryophase is completed in grasses and cereal grains. They attack a large number of hosts, such as oats, barley, rye, and many wild kinds of grass. They mainly attack grasses and cereal grains.

Complete answer:
Uredospores is formed by Puccinia on wheat. It causes black stem rust of wheat in almost all wheat-growing areas of the world, inflicting considerable damage on wheat. The presence of uredospores represents the first symptoms of the disease. Plants do not usually show disease symptoms up to 7 to 15 days of infection when the oval pustules of powdery, brick-red urediniospores break through the epidermis. The hyphae of mycelium aggregate to form a hyphal mass near the surface of the infected leaf, stem, or glumes. These hyphal masses surround isolated host cells which are called uredia. From the uredium arise large numbers of Uredospores. The group of Uredospores thus formed is known as uredospores. The spores are produced on long stalks and each spire is binucleate, somewhat oval to round in outline with a warty wall and four equatorial germ pores. The formation of a large number of Uredospores and the elongation of their stalk will lead to the cracking of the host epidermis to expose the Uredospores.

Additional Information:
-Wheat is the primary host upon which the dikaryophase of the pathogen is completed.
-This phase consists of a dikaryotic mycelium and two spore stages, namely uredineal stage and telial stage.
-The aeciospores, produced in the aecidial cups on the lower surface of the barberry leaves, bring about the primary infection.

So, the correct answer is ' Wheat'.

Note:
-Aecidiospores are binucleate. When they fall upon a Wheat plant or any other suitable host plant, they germinate.
-They put forth a germ tube or primary hypha that enters into the host through the stoma.
-The mycelium is branched, septate and it ramifies in the intracellular spaces of the host tissue.