pThis book provides a comprehensive update on the recent developments concerning the role of plant neurotransmitters in signaling and communication. Physiological investigations over the past few decades have demonstrated that plants employ neurotransmitters in various signaling pathways. Plant-based neurotransmitters serotonin, melatonin, dopamine, acetylcholine, and GABA share biochemical similarities with those in animal systems in terms of their chemical nature and biochemical pathways. Plant-environment interaction associated with abiotic stress management, growth modulation, flowering, circadian rhythm, fruit ripening, and allelopathic interactions are a major focus of research in the field, and recent advances in genomic, trascriptomic, and metabolomic approaches have resulted in the deciphering of the molecular mechanisms associated with various neurotransmitters in plants. Other current and potential areas of investigation include the putative phytohormone phytomelatonin, and