Fibonacci Analysis of Megasporogenesis and Megagametogenesis Life Cycles of Brassica rapa

Tracy Williams Department of Biological Sciences, York College of Pennsylvania

INTRODUCTION• Brassica 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 (Φ) value of 1.6180339 at the 18th division with mean width being 10-50.5% of mean length.

METHODS

Planted 8 wells of B. rapa following lab procedure

RESULTS

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 (Φ) 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.

REFERENCES• Amato, 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 later

Fixed inflorescences in FPA50 and stored in 70%

ETOH

Performed serial dehydration from 70-100%

ETOH

Cleared inflorescences using Herr clearing

technique

Determined stage of inflorescence, recorded ten

widths and lengths from each stage, performed Fibonacci summation

DIVISION MMC DYAD TETRAD 12 3133.3 1.618038916 3037.08 1.618032839 3936.46 1.618018077 13 5069.78 1.618032107 4914.10 1.618034428 6369.35 1.618040066 14 8203.08 1.618034708 7951.18 1.618033821 10305.81 1.618031667 15 13272.86 1.618033714 12865.28 1.618034053 16675.16 1.618034875 16 21745.94 1.618034094 20816.46 1.618033964 26980.97 1.61803365 17 34748.80 1.618033949 33681.74 1.618033998 43656.13 1.618034118 18 56224.74 1.618034004 54498.20 1.618033985 70637.10 1.618033939 19 90973.54 1.618033983 88179.94 1.61803399 114293.23 1.61834008