Document Type

Dissertation - Open Access

Award Date


Degree Name

Doctor of Philosophy (PhD)

Department / School

Agronomy, Horticulture, and Plant Science

First Advisor

Jose Gonzalez-Hernandez


Plant microbial interactions consist of the many relationships between plants and microbes which involve studies that observe the biology and molecular genetics of pathological, symbiotic, and associative interactions. Worldwide studies involving these interactions are scarcely available in wheat (Triticum aestivum L.). In South Dakota (SD), wheat research is a major platform used to understand the nature and consequences of these interactions. Specifically, our research efforts here at South Dakota State University (SDSU) concentrate on two different, but valuable, interactions in wheat: the fungal pathogen that causes fusarium head blight (FHB) and the symbiotic interaction of arbuscular mycorrhizae fungi (AMF) with wheat. These interactions were selected to help provide a better understanding of plant microbial interactions in wheat. In our first project, we studied FHB, which is one of the most devastating plant diseases in the world. It is responsible for significant economic loss due to lower crop yield and quality, as well as human health concern due to mycotoxin accumulation in infected grains. To date, no sources of resistance conferring complete resistance to FHB have been identified in wheat. Using double haploid (DH) populations derived from selected four-way crosses combining several sources of resistance, we developed wheat lines that display resistance to FHB. Screening evaluations followed by selections were conducted using both DH spring and winter wheat populations to further evaluate the potential usage of this material to enhance adapted wheat germplasms. Selection for resistance quantitative trait loci (QTL’s) and the use of fungicide (Prosaro) are two different approaches, which when combined, may present a better way of minimizing disease damage. We conducted a field experiment to evaluate the effect of combining resistance QTL’s and fungicide application on FHB severity. In our second project we studied AMF, which forms a mutualistic symbiotic interaction with the majority of land plants. Like many plant microbial interactions, not much information is available on AMF and wheat. Consequently, we conducted a field study to examine the contribution of AMF to nutrient uptake and biomass yields of spring wheat genotypes. Our results demonstrate that there are differences in mycorrhizal responsiveness and nutrient efficiency with the presence of AMF on wheat. This could suggest that there is a genetic control of these genotypic differences. Overall, our findings assist ongoing efforts aimed to describe the causes and benefits of these plant microbial interactions. Our studies are potential baselines that can assist both development and production of wheat and other major crops.

Library of Congress Subject Headings

Wheat -- Diseases and pests.
Fusarium diseases of plants.
Vesicular-arbuscular mycorrhizas.
Plant-pathogen relationships.



Number of Pages



South Dakota State University



Rights Statement

In Copyright