Graduate Theses and Dissertations (2019 - present)

Date of Award

12-2025

Document Type

Thesis

Degree Name

M.S.

Department

Biological Sciences

Committee Chair

Juan Mata, Ph.D.

Abstract

This study presents the first comprehensive taxonomic and ecological investigation of endophytic fungi (EF) associated with the submerged aquatic macrophyte Vallisneria neotropicalis in the southern United States. Over a 12 month period, from April 2023 to March 2024, leaf samples were collected from two distinct sites in Mobile Bay, Alabama a disturbed, brackish Causeway location and a cleaner, less impacted site at Meaher State Park. Using culture dependent methods, a total of 257 fungal endophytes were isolated from 1,200 leaf segments. All isolates belonged to the phylum Ascomycota, distributed across 3 classes, 6 orders, 10 families, and 19 taxa. The community was numerically dominated by the genera Penicillium (46.1% of isolates, 8 species) and Trichoderma (28.1%), with Penicillium chrysogenum as the most abundant species. Diversity indices indicated a community of moderate richness (Shannon Wiener H′ = 2.32; Simpson’s 1 D = 0.847) and high evenness (E = 0.79), consistent with patterns of specialized, lower diversity fungal assemblages previously observed in other Vallisneria species. A strong vertical gradient was observed within leaves, with the middle (47.3%) and bottom (42.9%) segments harboring significantly more isolates than the top segment.

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