Turtlegrass (Thalassia testudinum) undergoes a coordinated hypersensitive response when challenged with pathogenic Labyrinthula sp.

Author

Ava Vasile Larson, University of North FloridaFollow

Year

2024

Season

Fall

Paper Type

Master's Thesis

College

College of Arts and Sciences

Degree Name

Master of Science in Biology (MS)

Department

Biology

NACO controlled Corporate Body

University of North Florida. Department of Biology

First Advisor

Dr. Cliff Ross

Second Advisor

Dr. Mya Breitbart

Third Advisor

Dr. Bradley Furman

Fourth Advisor

Dr. Scott Jones

Department Chair

Dr. James Gelsleichter

Abstract

Infection of the subtropical seagrass Thalassia testudinum Banks ex König by pathogenic Labyrinthula sp. was found to induce lesion progression, alterations to the host’s oxidative metabolism, and production of defense metabolites over the early stages of infection (monitored over a 72-hr time course). By 48-hrs post-infection, host oxygen consumption, internal reactive oxygen concentrations, and caspase-3 proteolytic activity reached their highest levels. The formation of reactive oxygen species (ROS) and nitric oxide (NO) were detected in T. testudinum lesions by use of redox-sensitive probes/substrates and fluorescent imaging. To our knowledge, this work represents the first time NO has been detected in a marine angiosperm within the context of a plant-pathogen interaction. Hydrogen peroxide production and lesion expansion were highly regulated in the presence of diphenyleneiodonium, catalase, and carboxy-PTIO, suggesting crosstalk between ROS and NO activity. Using a nontargeted metabolomics approach, succinic acid, 3-phenylpropionic acid, and methyl p-coumarate concentrations were found to significantly increase following Labyrinthula sp. infection. The generation of characteristic seagrass wasting disease lesions likely results from cell death via the host’s hypersensitive response (HR) as well as direct degradation of tissue by the pathogen. These results highlight the existence of a co-evolutionary arms race between seagrasses and Labyrinthula sp. that shape the ecology and evolution of seagrass wasting disease.

Suggested Citation

Larson, Ava Vasile, "Turtlegrass (Thalassia testudinum) undergoes a coordinated hypersensitive response when challenged with pathogenic Labyrinthula sp." (2024). UNF Graduate Theses and Dissertations. 1306.
https://digitalcommons.unf.edu/etd/1306