Ryan Preble
Year: 2021
Faculty Advisor: Adrienne Roeder

“Characterization of ATML1 Transcription in Giant Cell Patterning in Arabidopsis thaliana using in vivo Imaging”

Project Summary:

The cereal crops represent a critical source of human nutrition. The primary purpose for growing grains is for their endosperm: a nutritious, often endoreduplicated tissue that fills the seed. Unfortunately, though understanding endoreduplication may be key to increasing grain yield, it is inconvenient to study in grain crops directly due to inaccessibility of seeds for imaging during development. Some epidermal cells of A. thaliana (giant cells), however, undergo endoreduplication and are easily accessed on the surface of the plant. In A. thaliana, endoreduplication is known to occur as a result of fluctuations in the concentration of ATML1 (ARABIDOPSIS THALIANA MERISTEM LAYER 1), a homeodomain transcription factor. This study aimed to determine if the fluctuations in ATML1 during development are controlled by transcriptional or posttranscriptional means by live-imaging ATML1 transcription in the floral meristem. We transformed ATML1 loss-of-function mutants with a transgene utilizing PP7 stem loops that enabled transcriptional imaging. We then successfully developed lines that could be imaged in-vivo for their transcriptional activity and displayed rescue of the wild-type giant cell phenotype. Based on preliminary imaging data, ATML1 accumulates in every epidermal cell, but few cells are actively transcribing ATML1. This may indicate that transcription does not happen uniformly, implying transcriptional control. In the future, we will quantify the relationship between transcription and the concentration of ATML1 in epidermal cells to justify if ATML1 fluctuations occur due to transcriptional or posttranscriptional means. In addition, we will further investigate the activity of ATML1 by identifying key target genes and biochemical pathways.

My Experience:

Working in a lab this summer gave me a brand new perspective on the types of work performed by plant biologists. It not only gave me great comfort that being a scientist is not as mystical or far-off as I once envisioned, but it also taught me a number of useful skills related to In addition, I was given the chance to expand my computational skills by writing scripts to find binding motifs and interpreting the results of gene ontology and differential expression analyses. I knew going in that I wanted to continue studying biology in graduate school, but now I feel confident in my ability to do so both in a drylab and a wetlab. Thank you to Vijaya, Adrienne, the members of the Roeder Lab, and staff and faculty at BTI for giving me this fantastic summer internship!