Regulation of anti-herbivory compound production in Arabidopsis thaliana
Embargo Date
2026-03-05
OA Version
Citation
Abstract
Rapid fluctuations in the environment caused by climate change have created new challenges for agriculture as many crop species will be more frequently exposed to abiotic stresses they are not adapted for. Since plants typically respond to stress by producing defense compounds, climate change will likely alter plant metabolism. Therefore, understanding the molecular mechanisms regulating plant defense in relation to metabolism can inform methods for engineering more stress-tolerant plants. In the Celenza lab, past experiments have focused on studying defense compounds derived from the tryptophan pathway in Arabidopsis thaliana, a convenient model plant species. This thesis builds on past experiments by quantifying chemical production and gene expression in mutants with significantly altered tryptophan metabolism to determine the systems level effects of altering this metabolic pathway.
This research focuses on eight different Arabidopsis mutant strains that have single or combined mutations that alter tryptophan synthesis and/or catabolism. Each mutation changes levels of tryptophan and/or tryptophan-derived defense compounds which was verified with HPLC analysis. In most cases, these mutations also affect overall plant health. Using mRNA extraction followed by RT-qPCR, data reveals that tryptophan-derived defense compound biosynthetic genes such as CYP79B2 have significantly elevated gene expression in most of the mutants tested when compared to wild type. This suggests that both increased and decreased tryptophan metabolism trigger a defense response. These results were followed up using differential gene expression analysis of RNA-seq data and GO-term enrichment to assess global transcriptional changes. From this data we found that tryptophan mutants also have alterations in expression of genes involved in photosynthetic processes. To further explore this, mutants were tested for metabolic responses to abiotic stressors such as high light intensity and increased ambient temperature and showed differential production of defense compounds in response to these stressors. Overall, these findings suggest that perturbing tryptophan metabolism has system-wide effects that can impact plant growth and defense.
Description
2024
License
Attribution 4.0 International