Signaling Peptides: Hidden Molecular Messengers of Abiotic Stress Perception and Response in Plants

Abstract

Abiotic stress constitutes a threat to plant growth and development owing to undesired morphological, physiological, biochemical and molecular changes leading to yield losses and also restricting the areas where the crops can be grown. However, the sessile nature of plants allows them to swiftly recognize and respond to various adverse climatic conditions. This rapid response is primarily due to effective cell-to-cell communication through various intricate defence machineries that enable the plants to sense stress and relay the signal to downstream response regulators. Till a few decades back, phytohormones were considered the major players of cell-to-cell communication. However, following the discovery of first signaling peptide, systemin in tomato, there has been a paradigm shift in our understanding of the role of these peptides in signaling in plants. Genome-wide approaches using the tools of bioinformatics, genetic screens and biochemical assays have led to the discovery of several novel plant peptides over the few years. Small signaling/peptide hormones/secreted peptides are now established in plants as molecular messengers because of their involvement in key developmental processes such as meristem maintenance, organ abscission, cell elongation, cell proliferation and differentiation, gravitropism and defence against abiotic and biotic aggressors. A better understanding of these signaling molecules might steer us towards manipulating them for engineering hitherto elusive stress tolerance trait in plants.