Date on Senior Honors Thesis


Document Type

Senior Honors Thesis

Degree Name




Degree Program

College of Arts and Sciences

Author's Keywords

ppal; Arabidopsis; gametophyte; plant development


Prenylation is a type of post-translational modification in which a 15- or 20-carbon lipid is added to the carboxyl (C) terminus of the protein. Arabidopsis thaliana contains the PROTEIN PRENYLTRANSFERASE ALPHA SUBUNIT-LIKE (PPAL) gene, which encodes a protein with homology to the α-subunits of the three known prenylation enzymes, PFT, PGGT, and Rab-GGT. We previously identified two mutations in PPAL, one of which is ppal-1, which contains a T-DNA insertion in the fourth intron. We have previously observed that self-fertilizing heterozygous ppal-1 plants produce progeny in which homozygous ppal-1 is underrepresented. This project attempts to ascertain possible affects of ppal-1 in gametophyte growth and development that might cause this underrepresented homozygous ppal-1 population.

Crosses were performed between homozygous ppal-1 and wild-type (WT) plants. Both F0 and F1 generations were genotyped. The results indicated that there was WT contamination of the ppal-1 F0 population. The data also indicated the ppal-1 primers were nonfunctional. Additionally, a pollen germination test was performed for both ppal-1 and WT plants. The results indicated that ppal-1 pollen had developmental delays for germination, but upon germination, they could form pollen tubules of equal length to the WT pollen. However, due to the likely WT contamination in the ppal-1 population used, these experiments must be replicated in further studies.

Lay Summary

As the world shifts away from fossil fuels and towards renewable energy, new sources of renewable energy are needed. Bioethanol could be one of these sources, but currently it is an energy negative source, meaning that it takes more energy to produce than the final product contains. One possible solution comes from studies of Arabidopsis thaliana plants with a mutation known as ppal-1. This mutation causes the hyperaccumulation of sugars, which is a desirable trait in a potential bioethanol source because it has the potential for creating bioethanol sources that are energy positive. However, ppal-1 mutants are difficult to acquire from populations with both wild-type and mutant genes. These developmental issues are important to understand and resolve if ppal-1 mutants are engineered into agricultural crops for biofuel. The purpose of this project was to study the differences in development between the wild type and mutant Arabidopsis plants.

By looking at the pollen of the plants, it was noted that mutants were not as good as wild type plants at pollen germination, which is a necessary process to fertilize the plant. These results, however, were somewhat overstated as it was later found that some of the plants that were supposed to be mutants were, in fact, wild type. In other words, there was wild type contamination within the mutant population. However, even with the contamination, these results were conclusive enough to warrant further study of how the pollen of wild type and mutant plants affects development.

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