Date of Award

2019

Degree Type

Thesis

Degree Name

Honors Thesis

Department

Biology

First Advisor

Nathanael Hauck

Abstract

Systemic acquired resistance (SAR) and the hypersensitive response (HR) are two important induced defense mechanisms in plants. SAR is the development of an enhanced resistance to a pathogen due to a prior encounter. It results in faster and more effective defensive action within the plant upon a second-time pathogen attack. HR is a plant defense mechanism that utilizes reactive oxygen species (ROS) to attack pathogens at the site of an infection. ROS can be generated in many ways; however, it is specifically known that plants use the enzyme peroxidase to generate the ROS hydrogen peroxide during HR. Plants also use the enzyme catalase to generate water from hydrogen peroxide in order to contain and control the toxicity. Much is known about SAR and HR in economically important vascular plants such as rice and corn; however, they have only recently been identified in nonvascular plants such as moss. This study aims to identify and characterize the roles of peroxidase and catalase in HR and SAR in the model moss species Physcomitrella patens; specifically, how the expression of peroxidase and catalase genes in this species is affected by exposure to the fungal elicitor β-glucan. This will provide insight into the SAR and HR of moss and other nonvascular plants and into the evolution of plant defense mechanisms.

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