First Advisor

Mitchell Cruzan

Date of Award

Spring 2021

Document Type


Degree Name

Bachelor of Science (B.S.) in Biology and University Honors






Cell division, Erythranthe guttata, Somatic cells, Plant mutation, Growth (Plants)




Plants are seemingly immortal in their abilities to survive long periods of dormancy in different life stages, live for thousands of years, and even grow into whole forests from one clone, all through a series of mitotic and meiotic events, but how many mutations do plants acquire in their lifetime? And just how many of these mutations are heritable? To answer these questions, first we must answer: how many cell divisions are there in the length of a stem? The purpose of this study is to answer just that by establishing a protocol for estimating the number of germ cell divisions required for a stem growth. I used a histological approach to generate a reliable model of stem growth and number of cells required for stem construction for downstream genomic analyses of somatic mutation rate to estimate the per-cell generation mutation rate along the length of a stem. Longitudinal and cross-sectional stem samples of an emerging model plant, Mimulus guttatus were made and stained to identify individual cells. Cells were counted to estimate the number of cells produced from meristematic cells in a standard length of stem for early growth and for mature stems (late growth). I used these estimates with a model for cell population growth to estimate the number of cell generations required to construct the stem when starting with different germ cell population sizes. In a separate study, sequential samples will be sequenced for transcribed regions (the exome) to identify new mutations that arise through mitotic division. Meristematic cell division rates will be combined with information on mutation rates to determine a per cell generation mutation rate, which will be used to estimate the potential for somatic mutation accumulation during vegetative growth.


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