Regulation of DNA (de)Methylation Positively Impacts Seed Germination during Seed Development under Heat Stress

Abstract

Seed development needs the coordination of multiple molecular mechanisms to promote correct tissue development, seed filling, and the acquisition of germination capacity, desiccation tolerance, longevity, and dormancy. Heat stress can negatively impact these processes and upon the increase of global mean temperatures, global food security is threatened. Here, we explored the impact of heat stress on seed physiology, morphology, gene expression, and methylation on three stages of seed development. Notably, Arabidopsis Col-0 plants under heat stress presented a decrease in germination capacity as well as a decrease in longevity. We observed that upon mild stress, gene expression and DNA methylation were moderately affected. Nevertheless, upon severe heat stress during seed development, gene expression was intensively modified, promoting heat stress response mechanisms including the activation of the ABA pathway. By analyzing candidate epigenetic markers using the mutants’ physiological assays, we observed that the lack of DNA demethylation by the ROS1 gene impaired seed germination by affecting germination-related gene expression. On the other hand, we also observed that upon severe stress, a large proportion of differentially methylated regions (DMRs) were located in the promoters and gene sequences of germination-related genes. To conclude, our results indicate that DNA (de)methylation could be a key regulatory process to ensure proper seed germination of seeds produced under heat stress.

DNA Methylation in Plant Responses and Adaption to Abiotic Stresses

“…For example, the LTR-copia-type retrotransposon ONSEN in Arabidopsis is activated by heat stress [46]. DMRs were identified in both gene sequences and promoter regions under both mild heat stress and severe heat stress, as well as in mitochondrial DNA in Arabidopsis [47].…”

“…It was observed that DNA demethylation caused by the ROS1 gene could impair seed germination by affecting the expression of germination-related genes. On the other hand, under severe heat stress, most of the DMRs are located in the promoters and gene sequences of germination-related genes [47].…”

Identification and Characterization of DNA Demethylase Genes and Their Association With Thermal Stress in Wheat (Triticum aestivum L.)

“…This demonstrated that the active demethylation process was triggered by HS (Korotko et al, 2021). DNA demethylation has also been linked to seed germination regulation during HS (Malabarba et al, 2021). The above results indicate that active DNA demethylation maintained by dMTases is a crucial process involved in various biological processes, including thermal stress regulation in plants.…”

Biogenesis, Trafficking, and Function of Small RNAs in Plants

“…RdDM can not only maintain long-term genome stability by inhibiting transposable elements but also ensure plants’ life activities under stress conditions by regulating gene expression ( Rymen et al, 2020 ; Guo et al, 2021 ). High temperature stress usually promotes RdDM ( Singh et al, 2021 ), which inhibits the expression of ROS1 gene due to hypermethylation and affects seed germination ( Malabarba et al, 2021 ). The slowdown of life activities may be beneficial to tolerate high temperature environments.…”