ThePun1gene for pungency in pepper encodes a putative acyltransferase

Abstract

). † These authors contributed equally to this work. SummaryPungency in Capsicum fruits is due to the accumulation of the alkaloid capsaicin and its analogs. The biosynthesis of capsaicin is restricted to the genus Capsicum and results from the acylation of an aromatic moiety, vanillylamine, by a branched-chain fatty acid. Many of the enzymes involved in capsaicin biosynthesis are not well characterized and the regulation of the pathway is not fully understood. Based on the current pathway model, candidate genes were identified in public databases and the literature, and genetically mapped. A published EST co-localized with the Pun1 locus which is required for the presence of capsaicinoids. This gene, AT3, has been isolated and its nucleotide sequence has been determined in an array of genotypes within the genus. AT3 showed significant similarity to acyltransferases in the BAHD superfamily. The recessive allele at this locus contains a deletion spanning the promoter and first exon of the predicted coding region in every non-pungent accession tested. Transcript and protein expression of AT3 was tissue-specific and developmentally regulated. Virus-induced gene silencing of AT3 resulted in a decrease in the accumulation of capsaicinoids, a phenotype consistent with pun1. In conclusion, gene mapping, allele sequence data, expression profile and silencing analysis collectively indicate that the Pun1 locus in pepper encodes a putative acyltransferase, and the pun1 allele, used in pepper breeding for nearly 50 000 years, results from a large deletion at this locus.

Genome sequence of the hot pepper provides insights into the evolution of pungency in Capsicum species

“…3a). Although the biosynthetic genes have been npg partly elucidated [33][34][35] , the biochemical reactions, evolution and regulation of capsaicinoid biosynthesis are still largely unknown. Using homology, microsynteny and previous reports 35 , we identified all orthologous genes of the capsaicinoid pathway in the tomato genome (Supplementary Fig.…”

“…Non-pungent peppers have a large deletion in CS that spans the region from the promoter to the first exon 33 . During placenta development, CS was highly expressed only in pungent pepper and was barely expressed in non-pungent pepper (Fig.…”

AT3 (Acyltransferase) Gene Isolated From Capsicum frutescens cv. Cakra Hijau

“…CS also serves as a regulator for the formation of capsaicin [9]. Acyltransferase (AT3) gene is proposed as a gene encode CS enzyme [10]. This statement is supported by Leung [11] who proposesthat AT3 is expressed at placenta and this gene is segregated at C locus.…”

Pun1 Gene Isolation from Capsicum frutescens L. cv Cakra Hijau

“…of Pun1 gene and a 4 bp deletation in part of exon-1 which distrub translation and so deletion of part of exon-2 including the stop codon [9][10][11].…”