Environmental Effects on the size of the Female Megagametophyte Stages in two Arabidopsis thaliana ecotypes

Olivia Gross and Bruce SmithYork College of Pennsylvania

Methods Results

Figure 1. Fibonacci Sequence analysis using mean width and length for Libya 2-nucleate stage

Figure 2. Fibonacci Sequence analysis using mean width and length for Canary Islands 8-nucleatestage

Objectives

Conclusion

Literature Cited

A – Functional Megaspore (Libya), B – 2-nucleate (Libya)C – 8-nucleate (Libya),D – 2-nucleate (Canary Islands)

Introduction

BA

C D

•Arabidopsis thaliana is a small flowering plant belonging to the Brassicaceae family. While of little agronomic importance, A. thaliana has become an essential tool in plant biology, as well as genetic and molecular research.

•There are nearly 800 ecotypes of A. thaliana found all over the world. They available through Ohio State University’s seed stock center, Arabidopsis Biological Research Center (ABRC 2009).

•Megagametogenesis is the development of a megaspore into an embryonic sac. The four stages being researched are the functional megaspore, 2-nucleate, 4-nucleate, and 8-nucleate.

•Previous research observed ovule development in megagametophytic stages of 5 species of Cornus L. using a new clearing technique (Smith 1975). Differences between species during this stage resulted in the suggested removal of C. florida from the genus Cornus.

•Similar research is necessary for the many different ecotypes of Arabidopsis thaliana.

•Investigate early ovule development through four stages of megagametogenesis in two ecotypes of Arabidopsis thaliana: CS1064 from an elevation of 1000 meters in the Canary Islands and CS1380 from an elevation of 250 meters in Libya.

•Ovule width and length measurements will be taken from each of the four stages.

•Data will be analyzed using the Fibonacci Sequence to determine if there are differences between the two ecotypes.

•It is hypothesized that the divergent environments of the two ecotypes will not affect the size of the female megagametophyte stages.

8 wells of each ecotype planted and placed in cold room for 5-7 days

CS1064 – Canary Islands

CS1380 –Libya

After cold treatment, plants placed under lights until inflorescences appeared

Inflorescences were removed and placed in FPA50 for a minimum of 24 hours

After removal from the FPA50, inflorescences dehydrated to 100% EtOH

Inflorescences continued to be removed from growing flowers and placed in FPA50

Dehydrated inflorescences placed in Herr fluid for 24 hours minimum before being viewed under microscope

Ovules dissected from pistil measured and recorded (minimum of 10 measurements per ecotype)

WIDTH: 8.73 LENGTH: 20.32 2.3276059561

29.05 1.4296259842

49.37 1.6994836493

78.42 1.5884140174

127.79 1.6295587865

206.21 1.6136630416

340.00 1.6197080657

540.21 1.617396518

874.21 1.6172780779

1414.42 1.61794076910

2288.63 1.61806959711

3703.05 1.61802038812

5991.68 1.61803918413

9694.73 1.61893200414

15686.41 1.61803474715

25381.14 1.61803369916

41067.55 1.61803409917

66448.69 1.61803394718

WIDTH : 14.33LENGTH: 54.98 3.8367062111

69.31 1.2606402332

124.29 1.7932477283

193.60 1.5576474374

317.89 1.6419938025

511.49 1.6090156976

829.38 1.6214979777

1340.87 1.616713698

2170.25 1.616838719

3511.12 1.61784126310

5681.37 1.61810761211

9192.49 1.61800586812

14873.86 1.6180447313

24066.35 1.61802988614

38940.21 1.61803555615

63006.56 1.6180333916

101946.77 1.61803421717

164953.33 1.61803390118

Fibonacci Sequence Results

•The 3-decimal phi constant, 1.618, and the 7-decimal phi constant, 1.6180339, were reached at the 11th and 18th divisions, respectively, for all four stages in both ecotypes.

•It is concluded that the divergent environments of Libya and the Canary Islands did not affect the size of the female gametophyte.

•Similar research needs to be conducted for all ecotypes of Arabidopsis thaliana to further research the relationship between environment and megagametophyte stages.

ABRC 2009. The Ohio State University. Available from:http://www.abrc.osu.edu/.Smith, B.B. 1973. The use of a new clearing techniquefor the study of early ovule development, megasporogenesis,and megagametogensis 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.I would like to thank Dr. Smith for his constant support and guidance throughout the senior thesis project.