Mycology Plant Pathology

Step 1: Understanding the Concept:
The question asks for the name of the specialized hyphae (filaments) in {Rhizopus} (a Zygomycete fungus) that grow towards each other to initiate sexual reproduction.
Step 2: Detailed Explanation:
Let's examine the terms related to sexual reproduction in {Rhizopus}:

Zygophores: These are the specialized, aerial, fertile hyphal branches that arise from compatible mating strains (+ and -). They are chemically attracted and grow towards each other. The name literally means "zygote bearer". This term correctly describes the hyphae mentioned in the question.

Progametangia: When the tips of two zygophores meet, they swell. These swollen tips, before a separating septum is formed, are called progametangia. They are the structures {at the tip} of the hyphae, not the hyphae themselves.

Chlamydospores: These are thick-walled, asexual resting spores formed by the rounding up of a hyphal segment. They are not involved in sexual reproduction.

Azygospores: These are spores that develop parthenogenetically (without fertilization) from a gametangium, but they look like zygospores. They are a type of spore, not a hypha.

Step 3: Final Answer:
The question asks for the name of the hyphae themselves, which are attracted to each other. The correct term for these specialized hyphal projections is zygophores.

Step 1: Understanding the Concept:
The question asks to arrange the stages of the life cycle of {Puccinia graminis} (the black stem rust fungus) in the correct order, beginning with the infection on its primary host, wheat ({Triticum aestivum}). This fungus has a complex life cycle involving two hosts (wheat and barberry) and five spore stages.
Step 2: Detailed Explanation:
Let's trace the life cycle starting on wheat:

Stage on Wheat (Summer): The disease first appears on wheat as reddish-brown pustules, which contain urediniospores. These spores are responsible for the repeating stage of the infection, spreading rapidly from one wheat plant to another during the growing season. This matches statement C.

Stage on Wheat (Late Summer/Autumn): As the wheat plant matures, the fungus switches to producing teliospores in the same pustules, which now turn black. These teliospores are the overwintering stage. This matches statement A.

Stage after Overwintering (Spring): In the spring, the diploid teliospores undergo meiosis and germinate to produce a basidium, which bears four haploid basidiospores. These basidiospores are then released. This matches statement B.

Stage on Alternate Host (Barberry): The basidiospores are unable to infect wheat. They are carried by the wind and must land on and infect the alternate host, the barberry plant ({Berberis} sp.). This matches statement D. (On the barberry, the fungus will produce pycniospores and then aeciospores, which will then infect wheat to start the cycle again).
Step 3: Final Answer:
The correct chronological sequence starting from the main disease stage on wheat is C (Urediniospores) A (Teliospores) B (Basidiospore discharge) D (Basidiospore germination on alternate host). This corresponds to option (C).