Serotonin serves as a plant defense chemical against fungi. When infected with Fusarium crown rot ("Fusarium pseudograminearum"), wheat ("Triticum aestivum") greatly increases its consumption of tryptophan to synthesize new serotonin. The function of this is poorly understood but wheat also produces serotonin when infected by "Stagonospora nodorum" - in that case to retard spore production. The model cereal "Brachypodium distachyon" - used as a research substitute for wheat and other production cereals - also produces serotonin, coumaroyl-serotonin, and feruloyl-serotonin in response to "F. graminearum". This produces a slight antimicrobial effect. "B. distachyon" produces more serotonin (and conjugates) in response to deoxynivalenol (DON)-producing "F. graminearum" than non-DON-producing.