introduction brassica rapa is a rapid cycling mustard plant from the brassicaceae family. it is...
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Fibonacci Analysis of Megasporogenesis and Megagametogenesis Life Cycles of Brassica rapaTracy Williams Department of Biological Sciences, York College of Pennsylvania
INTRODUCTIONBrassica rapa is a rapid cycling mustard plant from the Brassicaceae family. It is widely used as a genetic model system because it is fast growing, does not self-pollinate, and is genetically diverse.Megasporogenesis and megagametogenesis have been studied in a variety of plants. Most studies at York College of PA are done to investigate early ovule development, megasporogenesis, and megagametogenesis and determine the best clearing procedure by using many variations of Herr Clearing technique (Bankert, 1987). There is very little information or significant research that has measured differences in the megagasporogenesis and magagametogenesis life cycles of B. rapa.Fibonacci analysis utilizes anatomy, angles, and spirals to determine ratios that naturally occur in nature including plants and animals (Amato, 2010). This analysis allows for finding similarities in nature and allowing future comparisons of various plants such as B. rapa in future experiments.
OBJECTIVESTo investigate ovule development through all stages of megasporonenesis and megagametogenesis development of B. rapa and perform Fibonacci analysis to determine if there are any significant differences throughout the stages.
HYPOTHESISIt is believed that there will be no significant differences in ovule sizes throughout all stages of development as indicated by the ecotype reaching a Phi () value of 1.6180339 at the 18th division with mean width being 10-50.5% of mean length.
Planted 8 wells of B. rapa following lab procedureRESULTS
CONCLUSIONSFor all stages, except for the MMC and the Dyad, the width to length ratio ranged from 10%-50.5%. For the stages in this specified range, the 7-decimal phi () constant of 1.6180339 was reached at the 18th division. Therefore, there is no significant difference in the ovule sizes in the later stages and the two early stages are more of a round shape rather than an oval which can be expected. Future studies would provide a means for comparison to further explore the species relationships.
REFERENCESAmato, Dena. 2010. Does the environment affect the size of the female megagametophyte stages in Arabidopsis thaliana (L) Heynh ecotypes?Bankert, Thomas A., and Bruce B. Smith. 1987. Early ovule development, megasporogenesis, and megagametogenesis in Cichorium intybus L. (Asteracae). Pennsylvania Academy of Science. 61:109-112.Brown, Constance. 2008. Fibonacci Analysis. 1st ed. Bloomburg Press. New York, NY.Lohss, Shane. 2010. Examination and comparison of the Megagametophytic life cycle for mean length and width for two ecotypes of Arabidopsis thaliana.
ACKNOWLEDGEMENTSI would like to thank Dr. Bruce Smith for all of his guidance and expertise throughout this senior thesis experience.Thinned out plants after 13 days, removed inflorescences 7 days laterFixed inflorescences in FPA50 and stored in 70% ETOHPerformed serial dehydration from 70-100% ETOHCleared inflorescences using Herr clearing techniqueDetermined stage of inflorescence, recorded ten widths and lengths from each stage, performed Fibonacci summation