Question

Many fungi display the phenomenon of heterothallism. What exactly heterothallism?
A. Presence of different types of hyphae acting as male or female
B. Production of different kinds of spores
C. Presence of net-like mycelium
D. Ability to produce both sexually as well as asexually

Answer 1

Hint: This term is generally applied to the fungi which are capable of sexual reproduction from the single organism. It is somewhat related to the conjugation in Mucorales.

Complete answer :
In species where it has been shown that the thalli can differ in sex then it is proposed that the term heterothallism has been applied on them. There are two main types of heterothallism: two-allelomorph and multiple-allelomorph. In the heterothallic fungi, there are two different individuals that contribute nuclei to form the zygote. Examples of heterothallism are: penicillium marneffei, neurospora crassa. So, heterothallism is the presence of different types of hyphae acting as male or female.Because heterothallic fungi require sexes that have resided in different individuals. Morphologically, heterothallism may be defined as the situation wen the morphologically different female and male sex organs are produced in the two closely associated mycelia. The main function of heterothallism is to ensure outbreeding by encoding expression (sex-specific) of genes which is required during mating.

Thus, the correct answer is option A. i.e., Presence of different types of hyphae acting a male or female.

Note: This term heterothallism was first coming in light when Blakeslee in 1904 used this term for sexual reproduction in which he found that in species like Mucorales conjugation is possible through the two different thalli.