Scientists Decode Genome of the Hot Pepper

Posted on January 27, 2014

Hot Pepper photo from UC DavisAn international team of scientists have decoded the genome of the hot pepper. The researchers include scientists at the University of California, Davis. The hot pepper is the world's most widely grown spice crop. Annual global production of hot peppers has grown 40-fold in the past two decades and now exceeds $14.4 billion.

Hot peppers are members of the Solanaceae plant family. The researchers sequenced a hot pepper landrace, or domesticated variety, from the Mexican state of Morelos. The pepper is known as Criolo de Morelos 334. The researchers also provided sequencing data for the Perennial and Dempsey cultivated pepper varieties and for the related habanero pepper species (Capsicum chinense.)

The sequencing revealed blocks of genes in the hot pepper that appear in a similar chromosomal position in the tomato. The scientists say the pepper genome is 3.5 larger than the tomato genome.

The sequencing also uncovered evidence suggesting the "heat" of the hot pepper "originated through the evolution of new genes by duplication of existing genes and changes in gene expression after the peppers evolved into species." It has bee previously determined that the heat in hot peppers is caused by the accumulation of chemicals called capsaicinoids. Over 22 of these compounds have been isolated from peppers. This sequencing project will help scientists better understand how these compounds are synthesized in the pepper plant.

Study co-author Ryan W. Kim of the UC Davis Genome Center says in the announcement, "The whole genome assembly of pepper and comparative genomics to the closely-related tomato species, with its nearly four-fold smaller genome, provides new insights into evolutionary aspects of genome expansion in acquiring newly developed genetic function. The fine genetic mapping of pepper promises cost-effective and early screening for valuable agricultural traits."

The research was published here in Nature Genetics.

Photo: UC Davis