Investigating the role of epigenetics in rapid adaptation to stress in Arabidopsis thaliana and Sorghum bicolor

Abstract

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.