Araceli Aguilar-MelÚndez: Wild and Cultivated Chili Peppers

A study of former UC MEXUS-CONACYT Doctoral Fellow Araceli Aguilar-Meléndez, recently published in the American Journal of Botany, provides the first exploration of the genetic diversity and population structure of domesticated and semiwild chiles in Mexico.1 The chile of Mesoamerica, Capsicum annuum, is one of five domesticated chiles in the Americas that are consumed all over the world. Together with maize, C. annuum has been one of the principal elements of the neotropical diets of Mesoamerican civilizations for about 6,000 years.

Focusing on three DNA markers, Aguilar-Meléndez found an average reduction of about 10 percent in the diversity of domesticates relative to semiwild chiles and geographic structure within Mexican populations. She and her UCR academic advisers hypothesize that chiles were independently domesticated several times from geographically distant wild progenitors by different prehistoric cultures in Mexico. In contrast, maize and beans (also native to Mexico), appear to have been domesticated only once. Because of limited sampling, the study did not conclusively resolve the number and location of domestications, but several lines of evidence suggest multiple independent domestications from widely distributed progenitor populations. The preliminary data used in this study will play a part in future research regarding the origin of the domesticated chiles in Mesoamerica, Aguilar-Meléndez said.

She collaborated on this project with UC Riverside Assistant Professor of Plant Systematics Seung-Chul Kim and UC Riverside Professor of Genetics Mikeal L. Roose. The species that she examined, Capsicum annuum, produces several varieties of chile including the common bell pepper, poblano, and jalapeño chiles. This research stems from her dissertation, Evolutionary relationships between wild and cultivated chili peppers (Capsicum annuum L.) in Mexico using a DNA sequence of low copy nuclear gene and microsatellite data. She graduated from the UCR Department of Botany and Plant Sciences in 2006 and returned to Mexico as a full time professor/researcher at Centro de Investigaciones Tropicales (CITRO) at Universidad Veracruzana.

In addition to support from UC MEXUS, Aguilar-Meléndez's work was supported by El Consejo Nacional de Ciencia y Technología (CONACYT), and a gift from the McIlhenny Company. Dr. Araceli Aguilar-Meléndez can be contacted at araaguilar@uv.mx.

1 Araceli Aguilar-Meléndez, Peter L. Morrell, Mikeal L. Roose & Seung-Chul Kim, “Genetic diversity & structure in semiwild & domesticated chiles (Capsicum annuum; Solanaceae) from Mexico,” American Journal of Botany. June 2009.

2 Aguilar-Meléndez examined domesticated C. annuum var. annuum L. and semiwild C. annuum var. glabriusculum (Dunal) Heiser and Pickersgill based on DNA sequences at three nuclear loci, Dhn, G3pdh, and Waxy.