Lettuce (Lactuca sativa) is a leafy vegetable valued for its fiber and vitamin content. The crop is cultivated in open fields and greenhouses, occupying more than one million hectares globally. China, India, USA, Spain, Italy, Japan and Turkey are among the largest producers in terms of cultivated area. The annual global production value is around USD 10.8 billion.
Lettuce probably originated in Mesopotamia. From there, it dispersed to Egypt by 2500 BC, and later to Greece. It reached China between 600 and 900 AD, and America during the Columbian Exchange.
Genesys lists information for more than 9,000 accessions; 35% are held in the USDA-ARS genebanks, and 26% at the Centre for Genetic Resources, the Netherlands (CGN). The lettuce collection at CGN is considered the world’s most diverse.