Honors Theses

Date of Award

12-2024

Document Type

Undergraduate Thesis

Degree Name

BS

Department

Biology

Faculty Mentor

Taun Tran

Advisor(s)

Jeremiah Henning, Laura Frost

Abstract

Ralstonia solanacearum is a plant pathogen that causes bacterial wilt disease in major crops such as tomatoes and potatoes. Recently, this bacterium was discovered in floating pennywort (Hydrocotyle ranunculoides) and Pennsylvania smartweed (Polygonum pennysylvanicum), two previously unsuspected aquatic plants. Duckweed is an aquatic plant with a high level of resilience and short doubling time. Common duckweed (Lemna minor) has previously demonstrated its capability as a versatile high-yield infection model for other types of pathogenic bacteria. Given this newfound branch of aquatic hosts and the fact that duckweed is a common pond weed previously identified in several ponds located nearby infected crops, the goal of this project is to determine the host status of duckweed and evaluate its capability to perform as an agent for the spread of R. solanacearum. In order to establish both common duckweed and giant duckweed (Spirodela polyrhiza) as a potential host for this pathogen, we developed an infection assay in which the pondweeds were placed into a water-based solution containing the bacterium. Following inoculation, the plants were surface sterilized, homogenized, and dilution plated in order to quantify bacterial presence inside the plant material. A culture made from a resulting colony was then used to inoculate 3-week-old Bonny Best tomato plants. Plant wilting symptoms were recorded over a course of two weeks. The results of this study indicate that both common and giant duckweed can serve as a host to R. solanacearum and S.polyrhiza is capable of serving as an agent for the spread of Ralstonia.

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