The mutation disrupts tryptophan metabolism and induces cell death.

Tryptophan metabolism pathways are important components of the plant immune system; for example, serotonin is derived from tryptophan, and plays a vital role in rice () innate immunity. Recently, we isolated a rice mutant, (), which exhibits lesions. RNA-seq analysis revealed that KEGG pathways related to amino acid metabolism were significantly enriched in the transcripts differentially expressed in this mutant. Furthermore, measurements of free amino acid contents revealed the accumulated tryptophan of mutant. In addition, the transcript levels of genes related to tryptophan biosynthesis were significantly enhanced in the mutant. These results revealed that plays a critical role in tryptophan metabolism. Based on these findings, it is revealed that loss of function may disrupt tryptophan metabolism, thereby inducing cell death and forming lesions in rice.