A Gene Encoding a Putative Acyl-transferase Involved in Pungency of Capsicum

Abstract

Pungency in the fruit of pepper (Capsicum spp.) is due to the accumulation of capsaicinoids. We isolated two genes characterized as putative Capsicum acyl-transferase genes (Catf-1 and Catf-2) from the placenta of pungent pepper, which displayed consensus motifs of acyl-transferase, H***D and DFG*G. The expression pattern of Catf-1 coincided with the accumulation of capsaicinoids in pungent pepper. The Catf-1 was expressed in placenta of pungent pepper fruit, but not in other organs, such as leaf, flower, seed and pericarp. Accumulation of mRNA of Catf-1 varied with the developmental stages of the pungent pepper fruits. Genomic PCR and Southern blot studies revealed the presence of a sequence deletion at the 5′ end of the Catf-1 coding region in the non-pungent line. In the F 2 population obtained from a cross between a non-pungent strain ('mGTY-1') and a pungent strain ('277 long'), the genotype at the Catf-1 locus cosegregated with the phenotype for fruit pungency. These results suggest that Catf-1 is a candidate gene differentiating pungent from non-pungent peppers.

Potent Production of Capsaicinoids and Capsinoids by Capsicum Peppers

“…Suppression of pAMT by gene silencing has been shown to result in significant accumulation of capsinoids in a pungent pepper (19), implying that CS catalyzed the production of capsinoids from vanillyl alcohol generated instead of vanillylamine. CS possesses consensus motifs of certain plant acyl-transferases, some of which catalyze the reaction of benzyl alcohol with acyl-CoA to generate the corresponding esters (15,22,23). In this context, the findings of our metabolic flow study provide additional evidence supporting the contribution of CS to capsinoid biosynthesis.…”

“…Another important finding in our study relates to capsaicin synthase (CS), which catalyzes the condensation of vanillylamine with a fatty acid to produce a capsaicinoid (13)(14)(15)(16). In the present study, accumulation of capsaicinoids in Peru was inhibited by over 60% by the administration of vanillyl alcohol (Table 1), prompting speculation that the administered alcohol may compete with native vanillylamine that is normally incorporated into capsaicinoids in a reaction catalyzed by CS.…”

“…Furthermore, a putative acyltransferase (tentatively referred to as capsaicin synthase, CS) encoded by the Pun1 gene is regarded as a candidate enzyme catalyzing the condensation of vanillylamine with a fatty acid (13)(14)(15)(16). Given their structural resemblance, the biosynthetic pathways of capsinoids and capsaicinoids are thought to be closely related.…”

Evolución del conocimiento sobre la pungencia de la cebolla (Allium cepa L.) y del pimiento (Capsicum spp.): desde sus orígenes hasta el potencial nutracéutico actual. Revisión bibliográfica

“…A diferencia de los CAPs, los CTOs se forman por la condensación mediante un enlace éster, del alcohol vainíllico, común a todos ellos, con cadenas de ácidos grasos similares a las que intervienen en la formación de CAPs. La longitud, la presencia de insaturaciones y/o ramificaciones en la cadena de ácidos grasos determinará el tipo de CTOs/CAPs biosintetizados y el grado de picor (Curry et al, 1999;Lang et al, 2006). La estructura quí mica afecta a la intensidad del picor de cada compuesto, de este modo, los humanos somos capaces de percibir cada CAPs por separado; por ejemplo, la Cap y la dhCap son los más irritantes, la homodihidrocapsicina es muy irritante pero también penetrante y punzante y la ndhCap es la menos irritante (Bosland y Votava, 2012).…”

“…El gen dominante Pun1 (también conocido como locus C, lov, Catf-1) codifica para una enzima aciltransferasa (AT3), clave en la biosíntesis de CAPs y aparentemente, también de CTOs (Stewart et al, 2005;Lang et al, 2006;Han et al, 2013;Tanaka et al, 2017).…”