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 F2 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.