Date of Award:

12-2021

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Plants, Soils, and Climate

Department name when degree awarded

Plant, Soils, and Climate

Committee Chair(s)

Amita Kaundal

Committee

Amita Kaundal

Committee

Jeanette M. Norton

Committee

Youping Sun

Abstract

Due to the ever-changing climate and deterioration of the earth’s ecosystem, environmental stresses like abiotic (drought, salinity) and biotic stresses (pathogen infection) gravely affected plant growth. Native plants are a great way of improving these effects on the urban landscape. They can be used as ornamental plants in landscaping as they are accustomed to their natural environment. The Center for Water-Efficient Landscaping at Utah State University has released a list of plants to be used for low water use landscaping. One such native plant is Ceanothus velutinus (snowbrush ceanothus). They are evergreen plants that can grow in dry and harsh conditions and are native to the Intermountain West region of North America. This study focused on the effect of rhizosphere and endosphere microbiome on the growth and development of snowbrush ceanothus plants. A comparative metagenomic study in the bulk soil, rhizosphere, and endosphere of snowbrush ceanothus revealed the microbial diversity and presence of several plant growth promoting rhizobacteria (PGPR). So next, the effect of this native soil was observed on the growth and development of snowbrush ceanothus under the greenhouse conditions. Inoculation of native soil to the propagation media enhanced the rooting and survival rate of snowbrush ceanothus cuttings. The inoculation of native soil in the snowbrush ceanothus plants developed from cutting propagation and seedlings in the greenhouse revealed an improved growth compared to control plants. The metagenomic study of the rhizosphere and endosphere of snowbrush ceanothus plants treated with native soil revealed the presence of several PGPR that were absent in the control plants. Nodulation was observed for the first time in snowbrush ceanothus plants grown in the greenhouse and inoculated with native soil. So finally, an attempt was made to isolate as many PGPR species as possible from the rhizosphere and endosphere of snowbrush ceanothus plants. Many of these isolates tested positive for one or more specific traits such as siderophore production, indole acetic acid production, catalase production, nitrogen fixation, and phosphate solubilization. The isolates were further tested for their plant growth-promoting properties in plants. We found many of these bacterial isolates could potentially be used as bio-fertilizers or bio-stimulants.

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