Molecular Stress Response to Motor Oil and Salt Exposure in Sporobolus Alterniflora

Overview

Plant life in salt marshes is crucial to ecosystem regulation. Plants play key roles in ecological services, like carbon sequestration, soil enrichment, and flood protection, which have become increasingly important as carbon emissions increase and sea levels continue to rise. As sessile organisms, plants respond to environmental stressors by altering gene expression. Specific epigenetic modifications via DNA methylation represent one important way that plants can quickly respond to a changing, often stressful environment. Urbanization exposes plants to a variety of stressors, including increased salinity and oil exposure. To better understand how prolonged urban stressors cause molecular adaptations in estuarine plants, we measured %5-mc methylation levels, a well documented molecular indicator of environmental stress in plants. Marsh grasses were taken from two sites, the Bronx River, a highly impacted urban site, and Greenwich Cove, a less impacted suburban site. We chose a halophytic grass, Sporobolus alterniflora as our model organism because this species has a high salinity tolerance. Additionally, our previous studies have documented epigenetic changes in response to increased concentrations of a single stressor, motor oil. Sporobolus alterniflora is a dominant foundational species in urban estuaries. Thus, these studies will help us better understand adaptive mechanisms utilized by species that are critical to conservation efforts in urban estuaries. Since estuarine plants may face multiple forms of stress at once, we investigated the synergistic effects of two stressors: salinity and motor oil. After 4 days of exposure, we documented the following physiological changes: grasses exposed to both stressors lacked the structure to support the upper part of the plant, and the leaves were severely dessicated and discolored. In addition, we quantified molecular changes by way of documenting global methylation levels. Our data show that global methylation decreased when plants were exposed to increased salinity and motor oil, with the greatest decrease in methylation occurring when plants were exposed to motor oil only. For our site comparisons, the change in methylation levels was greater for the Greenwich Cove samples than for Bronx River samples. These preliminary results contribute to a growing field of research that demonstrates epigenetic modification in plants undergoing various types of stressors. In addition, our results suggest that epigenetic response in plants can vary according to levels of urbanization.

Competition history

• AJAS 2020 Category not listed

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