Question

Puccinia graminis tritici is:
A. Heteroecious
B. Heterothallic
C. Heteroecious and heterothallic
D. Heterokaryotic

Answer 1

Hint: Puccinia graminis tritici is a fungi that causes a disease called stem rust which causes disease in cereal crops. The disease caused by them is also called black rust and cereal rusts.

Complete Answer:
Puccinia graminis tritici belongs to the phylum of Basidiomycetes. In order to find out their nature, let us analyze the options.
Option A: A heteroecious parasite is the one that depends on two hosts to cause infection. The hosts on which this parasite spends its adult life is called the primary host and the other host for the rest of its life is called the secondary host. Puccinia graminis tritici Kentucky blue grass as its primary host and barbary as its secondary host. Therefore, this is the correct option.

Option B: Heterothallic organisms are those whose sexes reside in different individuals. Such organisms require two compatible partners to produce sexual spores. Puccinia graminis tritici are not heterothallic in nature. Therefore, this is the incorrect option.

Option C: Puccinia graminis tritici are heteroecious in nature but they are not heterothallic. Therefore, this is the incorrect option.

Option D: Heterokaryotic are those species in which cells have two or more genetically different nuclei which share one cytoplasm. Puccinia graminis tritici are not heterokaryotic. Therefore, this is the incorrect option.

Thus, the correct option is A) Heteroecious.

Note: Crop species that are affected by the disease include bread wheat, durum wheat, barley and triticale. Both the primary host and an unrelated alternate host are required for the parasite to complete its life cycle.