Date of Award


Degree Type


Degree Name

Honors Thesis



First Advisor

Philip Vilani


Moss, and all plants in general, are constantly defending themselves against pathogenic infections from viruses, bacteria, and fungi. Defense mechanisms require energy from compounds such as ATP and thus, are driven in part by photosynthesis. However, mosses typically grow in low light areas. Therefore, I investigated the extent of light dependency of the HR defense mechanisms of Mnium cuspidatum in response to infection by the pathogen Pythium irregulare. First, I conducted a field study on the Butler University campus in order to identify the typical light environment for growth of.M. cuspidatum '[vPl]interms of both photometric and infrared/far-infrared light readings. After establishing the light conditions for growth of moss in the field, samples of moss grown in our lab were habituated to either 0, 12, or 24 hr light cycles, and then inoculated with P. irregulare and observed for 72 hrs. in order to quantify the responding HR defense mechanisms. Finally, lab cultured samples of M. cuspidatum were habituated to the same intervals of light exposure, inoculated with the same fungal pathogen, and then assayed for catalase levels in order to quantify the expression of a biochemical commonly associated with the HR defense response in plants. Establishing the typical light environment in which M. cuspidatum is found in the field and quantifying both the morphological and physiological HR responses to fungal infection all come together to address this issue of the importance of light in the moss defense system.

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