Plants are sessile organisms and have developed varied mechanisms to tolerate stress. One such mechanism is DNA methylation, which plays a vital role within and across generational stress adaptation. To understand the role of DNA methylation in transgenerational stress adaptation, we exposed Arabidopsis thaliana for four generations of sub-lethal doses of glyphosate, trifloxysulfuron, clipping, and shading, which we further classified into the broader categories of stress ecological (shading and clipping) and herbicides (glyphosate and trifloxysulfuron). We analyzed phenotypic and whole-genome bisulfite sequencing data and found that the Arabidopsis phenotype adapts more rapidly to herbicide stress as compared to ecological stresses. DNA methylation changes for glyphosate were minimal after four generations of stress whereas the other three stresses showed dynamic change in the DNA methylation patterns. To understand within generation stress response, Sorghum bicolor was exposed to the same stresses at sub-lethal doses and we analyzed its phenotypic, whole genome bisulfite sequencing, and gene expression responses. Ecological stresses had higher negative impact on S. bicolor plant growth as compared to herbicide stresses. Similarly, we found higher differentially expressed genes for clipping as compared to both herbicides. All four stresses changed the methylome in a unique way; where we found 998 differentially methylated regions (DMR) for trifloxysulfuron, 193 for shading, 141 for clipping and 60 for glyphosate. Out of these DMR's some occurred genic region, which could potentially change gene expression and help plants withstand stress. Overall, DNA methylation can potentially help plants to withstand stress due to their dynamic and specific response to a variety of stresses both transgenerational and within generation. This information to better understand stress adaptation mechanisms in plants and used to develop stress-resilient crops. / Doctor of Philosophy / Environmental and anthropogenic stresses can negatively impact plant growth and development. Plants can have stress memory through epigenetic changes which helps them withstand stress in future generations. Epigenetics is the field of science where changes on the DNA and not sequence, that can be an addition or deletion of a methyl group, modification of histones, or production of small RNAs. We wanted to understand short and long-term effects of common anthropogenic and ecological stresses on how DNA methylation changes can help plants to withstand stress. We used the model plant Arabidopsis thaliana and the non-model crop/weed Sorghum bicolor. We exposed plants to sub-lethal doses of two herbicides, clipping, and shade stress, at levels high enough to cause significant visible injury but still allowed them to recover and reproduce for a single generation for S. bicolor and four generations for A. thaliana. We found that A. thaliana rapidly more adapts to herbicide stress as compared to ecological stresses. DNA methylation changes for glyphosate were minimal after four generations of stress whereas the other three stresses showed dynamic changes in the DNA methylation patterns. Each stressed impacted S. bicolor phenotype, DNA methylation, and gene expression in unique ways. We found ecological stresses greatly affected the phenotype of the S. bicolor plants as compared to herbicide stresses. Overall, our results showed that stress can cause DNA methylation changes and in transgenerational stress DNA methylation can potentially play a role in stress adaptation. This information could be useful for scientists to further understand stress resilience in plants.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/110500 |
| Date | 08 June 2022 |
| Creators | Sharma, Gourav |
| Contributors | Plant Pathology, Physiology and Weed Science, Barney, Jacob, Askew, Shawn D., Westwood, James H., Haak, David C. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Dissertation |
| Format | ETD, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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