Samuel Weldon

Date of Award

2016

Document Type

Thesis

Degree Name

Bachelors

Department

Natural Sciences

First Advisor

Clore, Amy

Keywords

Rhizobacteria, Bacterial Communities, Maize, Plant Tissue, Plant Growth

Area of Concentration

Biology

Abstract

Plant-associated bacteria include those bacteria that reside within the tissues of the plant, known as endophytes, and those that reside on the surface, known as epiphytes. Previous work has shown that plant endophytic bacteria have complex relationships with their host, and often benefit the plant in many ways. Some examples of these benefits include increased nutrient uptake, increased resistance to pathogens, and growth enhancement. Rhizobacteria, a type of epiphyte found on the roots of plants, have well-documented positive impacts producing many of the same benefits to the host as do endophytic bacteria. Less is known about epiphytes on aerial plant tissues and their potential benefits. A previous thesis reported endophytic bacteria within the kernels of the maize (Zea mays L.) reference line B73. The aim of the present study was to investigate the total kernel-associated bacterial communities in the maize lines B73, CML322, and CML 103. Previous studies have reported unusual endosperm development patterns in the latter two lines of maize. The goal of the present research was to compare total bacterial communities to determine if there is a correlation between the observed growth patterns and the kernel-associated bacteria communities in these three lines in early stage maize kernels (between 0 days after pollination, or DAP, to 12 DAP). The communities of kernel-associated bacteria were analyzed during this time frame using TRFLP, a community level high-throughput molecular analysis technique that uses variation in the 16S rDNA gene to differentiate between phylotypes. Comparison between TRFLP profiles allowed for direct comparison of kernel-associated bacterial communities. The results indicated that there are differences in kernel-associated bacteria across lines of maize and within lines at different days after pollination. The investigation of kernel associated bacteria in developing maize kernels may have promise in agricultural applications. Future work could expand to determine the effects of manipulating kernel associated bacterial communities on growth period, crop yield, and pathogen resistance perhaps leading to decreased use of chemical and hormonal agents in agriculture.

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