Plants are challenged by biotic and abiotic stresses. They adjust to changing environmental conditions by adopting various measures to induce regulatory self-defense pathways in response to different stresses in order to maintain their genetic potential to optimally grow and reproduce. To minimize cellular damage caused by such stresses, phytohormones provide a number of signaling networks involvingdevelopmental processes and plant responses to environmental stress. Phytohormones are potential tools for sustainable agriculture in the future. Significant advances have been made in identifying and understanding plant-hormone signaling, especially salicylic acid.