Date of Award

2017

Document Type

Thesis

Degree Name

Bachelors

Department

Natural Sciences

First Advisor

Clore, Amy

Area of Concentration

Biology

Abstract

For life on Earth, there is no way to skirt the influence of gravity. The phenomenon of gravitropism – translation of the mechanical force of gravity to a chemical signal and the appropriate reorientation or growth response – is observed in some sense in every organism, but is poorly understood, especially in initial stages of sensing and signal codification. The molecular mechanisms of gravitropism remain relatively poorly understood in plants, whose sessile lifestyle requires a thorough and highly dynamic response to the gravitational force as a growth signal. In addition to addressing a fundamental question of biology, work in this area may find use in agriculture; lodging, a horizontal reorientation of a crop relative to gravity due to wind or other factors, has been suggested to be potentially remediable by enhancement of the gravitropic pathway. Finally, an intimate understanding of the way plants perceive and respond to gravity will be essential for designing an ideal life support system required of any long-term space habitation mission. The plant gravitropic response is generally divided temporally into three parts: sensing the force or change in force of gravity; transduction of this physical signal into a chemical one, and subsequent transmission from the site of sensing to the site of response; and the response phase, wherein differential growth, largely mediated by the growth hormone auxin, reorients the plant if necessary. The latter phase is the most well-understood, particularly the involvement of the auxin pathway, as well as the auxin transport system that typifies the later part of the transduction phase. These elements of plant gravitropism are extensively reviewed elsewhere and are only briefly summarized in this work, which highlights recent developments in the fields of gravity sensing and gravity-related mechanotransduction in higher plants. In addition to literature review focused on these early events, bioinformatics techniques are also employed in a preliminary fashion to identify potential subjects for future research.

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