Heterobasidion Is a Basidiomycete That Contributes to Mortality of Trees

question 46

Multiple Choice

Heterobasidion is a basidiomycete that contributes to mortality of trees. Kuhlman isolated 23 strains of Heterobasidion and applied them to 16 seedlings of 10 different tree species. Partial results of this experiment are shown in the table. (From Kuhlman, E. G. 1970. Seedling inoculations with Fomes annosus show variation in virulence and in host susceptibility. Phytopathology 60:1743-1746. https://www.apsnet.org/publications/phytopathology/backissues/Documents/1970Articles/Phyto60n12_1743.PDF)
% mortality of five host species from five Heterobasidion isolates
$$\begin{array} { | l | l | l | l | l | l | } \hline & \text { Isolate } & \text { Isolate } & \text { Isolate } & \text { Isolate } & \text { Isolate } \\\hline \text { Host } & 63 & 117 & 195 & 126 & 118 \\\hline \text { Slash Pine } & 50 & 69 & 94 & 100 & 94 \\\hline \text { Shortleaf Pine } & 75 & 56 & 94 & 94 & 100 \\\hline \text { Red Cedar } & 38 & 32 & 19 & 50 & 25 \\\hline \text { Yellow-Poplar } &0 & 0 & 6 & 6 & 6 \\\hline \text { Sycamore } & 0 & 0 & 0 & 0 & 6 \\\hline\end{array}$$
-Which of the following conclusions can best be drawn from these results?

• A) All tree species are susceptible to Heterobasidion.
• B) Heterobasidion strains are equally lethal to all tree species.
• C) Heterobasidion strains vary in their effect on tree species.
• D) Some strains of Heterobasidion reduce tree mortality.

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Definitions:

Thyroid Hormone

Hormones produced by the thyroid gland, primarily thyroxine (T4) and triiodothyronine (T3), crucial in regulating metabolism, energy generation, and child growth.

Hypothalamus

A region of the brain below the thalamus that coordinates both the autonomic nervous system and the activity of the pituitary, controlling body temperature, thirst, hunger, and other homeostatic systems.

Anterior Pituitary

The front part of the pituitary gland that secretes hormones responsible for regulating a wide range of bodily functions, including growth, reproduction, and metabolism.

Uterine Contractions

Involuntary muscular contractions of the uterus, important in menstrual flow, labor, and delivery of a fetus.