Poster: Secondary metabolism
Abs #
278: Isolation and Characterization of Pun1: A Key Regulator of Capsaicinoid Biosynthesis in Hot Peppers (Capsicum spp.)
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Presenter: |
Stewart, Charles E., cs265@cornell.edu |
Authors | Stewart, Charles E. (A) Liu, Kede (A) Kang, Byoung-Cheorl (A) Mazourek, Michael (A) Ben-Chaim, Arnon (A) Paran, Ilan (B) Yoo, Eun-Young (C) Kim, Byung-Dong (C) Jahn, Molly (A) | | Affiliations: |
(A): Cornell University
(B): Volcani Institute
(C): Seoul National University
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Pungency in Capsicum pods is due to the accumulation of capsaicin and its analogs in the dissepiment during fruit development. This biosynthesis is restricted to the genus Capsicum and results from the acylation of an aromatic moiety, vanillylamine, from the phenylpropanoid pathway, by a branched chain fatty acid. While some of the genes involved in capsaicin biosynthesis are known, regulation of this pathway is not fully understood. We surveyed a number of candidates based on the pathway model from databases and the literature, and determined that a published EST co-localized with the Pun1 locus on a genetic map of pepper. This gene has been isolated and its nucleotide sequence has been determined in an array of genotypes from several species within the genus. The recessive allele at this locus, used widely in pepper breeding for more than two hundred years, contains a deletion spanning the promoter and first exon of the predicted coding region. The allelic state at Pun1 is correlated with transcriptional regulation of a number of other genes encoding enzymes involved in capsaicin biosynthesis. An antibody raised against the Pun1 gene product confirmed that this protein is specific to the placenta/dissepiment, is expressed at the appropriate time during fruit development, and is stable. Current efforts are underway to elucidate the biochemical activity of this gene product. Our long-term goal is to understand the nature of the genetic changes that underlie the acquisition of this unique biosynthetic capacity in Capsicum.
