Genetic mapping revealed that the gene in encodes a putative aminotransferase.

Several genes regulating capsaicinoid biosynthesis including (also known as ), , , and have been studied. However, the gene encoded by in the non-pungent is unknown. This study aimed to identify the gene by genetic mapping using interspecific ( × ) and intraspecific ( × ) populations. QTL mapping using the interspecific F population revealed two major QTLs on chromosomes 3 and 9. Two bin markers within the QTL regions on two chromosomes were highly correlated with the capsaicinoid content in the interspecific population. The major QTL, on chromosome 3, contained the gene, indicating that the non-pungency of may be attributed to a mutation in the gene. Sequence analysis revealed a 7 bp nucleotide insertion in the 8 exon of of the non-pungent . This mutation resulted in the generation of an early stop codon, resulting in a truncated mutant lacking the PLP binding site, which is critical for pAMT enzymatic activity. This insertion co-segregated with the pungency phenotype in the intraspecific F population. We named this novel allele . Taken together, these data indicate that the non-pungency of is due to the non-functional allele, and encodes the gene.