Involved in serotonin biosynthesis. Catalyzes the conversion of tryptamine to serotonin (PubMed:21080162, PubMed:23053415, PubMed:20150424, PubMed:23521226). Accumulation of serotonin may play a role in innate immunity (PubMed:20150424). O2 + reduced [NADPH--hemoprotein reductase] + tryptamine = H(+) + H2O + oxidized [NADPH--hemoprotein reductase] + serotonin Expression increases in the panicle from 7 days before flowering to flowering stage, to become undetectable 7 days after flowering. Induced by N-acetylchitooligosaccharide elicitor and infection with a compatible race of the rice blast fungus Magnaporthe oryzae (PubMed:20150424). Induced by salt stress, methyl viologen, acifluorfen and cadmium (PubMed:23053415). Belongs to the cytochrome P450 family.