Measuring of Length and Width of Ovules from Arabidopsis thaliana (L.) HEYNH. undergoing Megagametogenesis and determining the Fibonacci

Sequence using the MeanAshad Syed* and Bruce Smith

York College of PA

Introduction

• Arabidopsis thaliana is widely studied due to its small genome and the many mutant lines available (Rédei, 1969, Bowman, 1994).

• The first quantitative study and detailed observations of ovule development of megagametophytic stages was of five Cornus L. species using a clearing technique (Smith, 1973, Smith 1975) .

• Clearing techniques allows you to halt the development of ovaries in certain stages and observe them with clarity using phase contrast microscopy.

• Morphological size disparities in the different developmental stages could be detected by calculating Fibonacci sequences in successive stages

• Many life-forms have the golden ratio in some aspects of their design e.g., flowering plants have petals that are fibonacci numbers such lilies, iris, corn, asters, etc

Objectives

• To obtain the Mean and CI of the length and width of megasporogenesis and megagametogenesis stages of A. thaliana .

• To use the means of the widths and lengths to see if the Fibonacci sequence can be determined (the golden ratio, phi)

Methods and Materials

Results

Conclusion•All four developmental stages were successfully measured

•The mean length and width of each stage resulted in the Fibonacci sequence and the golden ratio

•The changes in cell morphology throughout megagametogenesis were proportional as demonstrated by the golden ratio, phi

Literature CitedBowman. 1994. Arabidopsis: An Atlas of

Morphology and Development. Springer- Verlag, New York

Rédei, G.P. 1969. Bibliographia Genetica XXI: 1-151.

Smith, Bruce B. 1973. The use of a New Clearing Technique for the Study of Early Ovule Development, Megasporogenesis, and Megagametogenesis in Five Species of Cornus L. American Journal of Botany 60(4):

322- 338.

Smith, B, B. 1975. A Quantitative Analysis of the Megagametophyte of Five Species of Cornus L. American Journal of Botany 62(4): 387-394

Smyth, David R., Bowman, John L., and Meyerowitz, Elliot M. 1990. Early Flower Development in Arabidopsis. The Plant Cell 2:755-767.

Acknowledgements

I would like to thank Dr. Bruce Smith for his guidance and invaluable expertise throughout this project.

A. thaliana, Landsberg ecotypegrown from seeds

in greenhouse

Fixed for 24 hrs in FPA50 and then treated with ETOH dehydration treatment with 10-15 min exposure to each fluid

70% →80% →90% →95% →100%

Added to Herr Fluid

Observed under phase contrast microscope at 100x magnification

FM

2-nucleated cells

4-nucleated cells

8-nucleated cells

Measure length and width using software

Compute data to determine if Fibonacci sequence can be obtained (Golden Ratio)