Author ORCID Identifier

https://orcid.org/0009-0008-8874-4157

Date Available

8-1-2027

Year of Publication

2025

Document Type

Master's Thesis

Degree Name

Master of Science (MS)

College

Agriculture, Food and Environment

Department/School/Program

Plant and Soil Sciences

Faculty

Kendall Corbin

Faculty

Krista Jacobsen

Abstract

This thesis integrates ecological, agricultural, and evolutionary frameworks to advance our understanding of plant–microbe interactions in horticultural systems, focusing on nutritionally valuable crops. Rhizosphere microbial dynamics of broccoli (Brassica oleracea var. italica) were characterized across developmental stages, revealing a significant decrease in microbial diversity at mid-vegetative stages, associated with deterministic enrichment of beneficial taxa (Burkholderia–Caballeronia–Paraburkholderia). Domestication effects were assessed by comparing domesticated Brassica oleracea cultivars (broccoli, kale, collard greens) to their wild relative, Brassica cretica, demonstrating that domestication diminishes the host’s ability to selectively recruit beneficial rhizosphere microbes. Investigations of the phyllosphere microbiome highlighted critical methodological constraints due to overwhelming plant-derived DNA, emphasizing the need for improved techniques to accurately profile microbial communities in low-biomass leaf environments. Lastly, culture-dependent analysis of kale and lettuce established a collection of phyllosphere isolates, identifying taxa with agricultural and potential human health benefits, including probiotic candidates such as Bacillus and Rummeliibacillus. Collectively, these insights provide foundational knowledge for microbiome-informed strategies, emphasizing the potential to leverage beneficial plant–microbe relationships for sustainable agriculture, enhanced crop resilience, improved food safety, and positive impacts on human health.

Digital Object Identifier (DOI)

https://doi.org/10.13023/etd.2025.338

Available for download on Sunday, August 01, 2027

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