Exopolysaccharides Synthesized by Rhizospheric Bacteria: A Review Focused on Their Roles in Protecting Plants against Stress

CAREZZANO, MARÍA EVANGELINA; ALVAREZ STRAZZI, FLORENCIA BELÉN; PÉREZ, VERÓNICA; BOGINO, PABLO; GIORDANO, WALTER

Applied Microbiology

MDPI

Año: 2023 vol. 3 p. 1249 - 1261

Plants are constantly exposed to a wide range of environmental factors that cause differentkinds of stress, such as drought, salinity, heat, frost, and low nutrient availability. There are alsobiotic sources of stress, which include pathogens (bacteria, viruses, pests), herbivores, and plantcompetitors. These various types of stress affect normal plant physiology and development, and may lead to significantly lower yields. However, certain microorganisms (MOs), known as plant growthpromoting rhizobacteria (PGPR), can interact with and benefit plants in stressful environments. They do so through a series of mechanisms which contribute to minimizing the negative effects of plants’ responses to stress. This review summarizes current knowledge about those mechanisms, with a focus on the production of exopolysaccharides (EPSs). These compounds can act as osmoprotectants, promote the production of phytohormones, prevent the entry of pathogens through roots, bioremediate metals, and improve soil structure and permeability, among many other beneficial effects. This makes them suitable alternatives to guarantee food security while reducing the excessive use of chemical agricultural inputs and their harmful consequences for the environment.