MicroRNAs: An Emerging Class of Root Exudate Component of Wheat Response to Polluted Soil.

MicroRNAs (miRNAs) are recognized as key molecular regulators in most of intracellular processes essential for plant adaptation to environmental changes. microRNAs can mediate regulation of gene expression involved in development, acquisition of nutrients, defense and interactions with soil microorganisms to enhance stress tolerance of plants. Accumulating evidences indicate that microRNAs are also transferred within cells, organs or whole plant and released in soil as stress signals of the plant-microbiome communication. However, little information is available about how mobile microRNAs are conveyed from plants to the rhizosphere. To understand whether this intriguing phenomenon occurs through root secretion, morphological changes, Peroxidase (POX), superoxide dismutase (SOD) and catalase (CAT) antioxidant enzymes activities, as well as the expression profiles of developmental and oxidative stress responsive microRNAs were analyzed in root tissues and exudates collected from wheat (triticum aestivum) exposed to bisphenol A (BPA) at low and high concentrations (0.1 and 5000 mg. kg⁻¹ soil). BPA contamination significantly affected aerial and root biomass, and miR164, miR167 and miR398 expression in roots of the group that received the highest dose. The presence of miR156, miR164, miR167 was detected in root exudates of controls and contaminated plants while BPA exposure increased miR 167 levels in exudates at high dose. Collectively, this experiment provided first results reporting microRNAs regulatory network participation in the BPA stress response of wheat. The identification of microRNAs as integral component of the root exudates will extend our knowledge about the molecular signaling in plant—soil microbiome interactions. [ABSTRACT FROM AUTHOR]