Stress memory in response to benzoxazinoid allelochemicals in Thlaspi arvense

Plants grow in dynamic environments and are constantly exposed to different types of stresses. For instance, stress related to competition in allelopathic interactions. In these interactions, the donor plant releases toxins, termed allelochemicals, to inhibit growth of the surrounding flora. To cope with stress, plants have evolved a “stress memorizing” strategy that enables them to respond more efficiently when the stressor reoccurs (somatic memory). The molecular mechanisms by which memory is established are not well understood, but in some cases involve changes in gene regulation and epigenetic configuration. Here, we explore the role of DNA methylation mediated somatic memory in allelopathic interactions and adaptation to allelopathic environments in Thlaspi arvense. To this end, we designed a priming experiment using two priming stimuli with 3.5 µM of the allelochemical 2-aminophenoxazin-3-one (APO) on seedlings and analyzed methylation changes in root and shoot tissues. We found that APO treatment caused a reduction in root growth and induced global changes in DNA methylation in the CHH context in both root and shoot tissues. Analysis of differentially methylated regions (DMRs) showed that methylation changes occur in the proximity of genes involved in stress responses, defense, detoxification mechanisms and cell wall integrity.