Document Type

Thesis - Open Access

Award Date

2023

Degree Name

Master of Science (MS)

Department / School

Agronomy, Horticulture, and Plant Science

First Advisor

Madalyn Shires

Abstract

Wheat (Triticum aestivum L.) is one of the world’s most valuable crops, and the primary food grain produced in the United States. A major disease in wheat production is Bacterial Leaf Streak (BLS) caused by the gram-negative bacterium Xanthomonas translucens pv. undulosa (Xtu). Very few management strategies are available to growers to manage this disease, as common chemicals do not provide adequate control. A number of studies have been conducted on biological control using Rhizospheric bacteria for the control of various plant diseases, but limited data is available on the efficacy of biological control using Rhizospheric bacteria for controlling Bacterial Leaf Streak in wheat. The objectives of this study were to isolate and identify promising antagonistic bacteria from soil samples taken between South Dakota (SD) and North Dakota (ND) and evaluate their effects on Xtu in vitro and in vivo. Soil samples were diluted 10-fold before plating onto Nutrient Agar amended with glucose (NAG). Colonies of potential antagonistic bacteria were cultured for purity and the DNA was extracted using a Quick DNA Fungal/Bacterial Microprep kit before performing PCR. Sanger sequencing was completed for the 16S rRNA region where several different Bacillus spp., Klebsiella spp., Priestia spp., and Pseudomonas spp., were commonly found between both states. Bacterial isolates were screened in vitro for antagonism against Xtu using inhibition of growth on NAG as a screening method, where species within the Bacillus genera displayed the greatest amount of inhibition. Further screening was conducted in vivo using inoculants on soil, both pre-plant and at the time of planting as well as by inoculation of plants at different growth stages. Disease severity in vivo was not obtained, however, the results from in vitro screening allow for the conclusion that rhizobacteria have the potential to be used as effective biocontrol agents for controlling BLS.

Library of Congress Subject Headings

Wheat -- Diseases and pests -- Biological control.
Bacterial diseases of plants.
Leaf spots.
Rhizobacteria.

Publisher

South Dakota State University

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Rights Statement

In Copyright