Date of Award

2012

Document Type

Thesis

Degree Name

Bachelors

Department

Natural Sciences

First Advisor

Clore, Amy

Keywords

Endophytic, Bacteria, Maize, Development

Area of Concentration

Biology

Abstract

Endophytic bacteria reside inside of a host plant for part of or all of their life cycle without causing any apparent symptoms of disease. Most endophytes have a symbiotic relationship with their host, offering benefits such as increased nutrient uptake, stimulated phytohormone production, or improved resistance to pathogens and toxins. Endophytic bacteria have been well studied in various tissues of many different crops, but their potential presence has not been investigated in maize kernels at early developmental stages. The aims of this thesis research were to investigate the potential existence of endophytic bacterial communities in Zea mays L. (maize) kernels and then to address how any such bacterial communities change throughout the first 12 days of development following pollination. Potential endophytes were isolated from surface-sterilized kernels at 0, 1, 2, 3, 4, 6, 8, and 12 days after pollination with culturing techniques. Maize kernels were also probed for potential endophytic bacteria with fluorescent in situ hybridization and confocal microscopy. Metagenomic DNA (i.e., total DNA content of a sample, potentially consisting of genomes of multiple organisms) was isolated from surface-sterilized kernels at 0, 1, 2, 4, 6, and 8 days after pollination, and the presence of endophytic bacteria was assayed using polymerase chain reaction (PCR) with bacteria-specific primers. Bacterial community profiles were obtained with terminal restriction fragment length polymorphism (TRFLP) techniques. The results were inconclusive, but some aspects, particularly the TRFLP results, suggest the possibility of endophytic presence. The study of endophytic bacteria and how they influence development may lead to future studies that could yield promising agricultural applications to increase such aspects as crop yield, quality, longevity, and sustainability, thereby potentially limiting the use of chemical agents.

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