Signaling Peptides in Plants

In multicellular organisms, growth and development need to be precisely coordinated and are strongly relying on positional information. Positional control is achieved through exchanges of molecular messages between cells and tissues by means of cell-to-cell communication mechanisms. Especially in plants, accurate and well-controlled cell-to-cell communication networks are essential because of the complete absence of cell mobility and the presence of rigid cell walls. For many years, phytohormones were thought to be the main messengers exchanged between cells. Nevertheless, identification of systemin as the first plant signaling peptide in tomato hinted that peptide hormones were acting in plants as they were in animals. During the last decade, our knowledge of plant signaling peptides has progressed considerably and a number of signaling peptide families have been discovered and partially characterized. Here, we provide an overview of the current knowledge in signaling peptides in the model species Arabidopsis thaliana and discuss their proposed functions during plant growth and development.