Genetic Variation among Tomato Accessions from Primary and Secondary Centers of Diversity

Abstract

The Asian Vegetable Research and Development Center (AVRDC) maintains one of the largest collections of Lycopersicon germplasm. Approximately 60% of the collection is from Old World regions; however, it is unclear whether these accessions represent unique sources of genetic variation compared with accessions from New World regions. The objective of this study was to compare the magnitude and structure of genetic variation among tomato accessions collected from Old and New World regions. Forty‐one random amplified polymorpbic DNA (RAPD) primers generated 98 polymorphic RAPD markers and were used to estimate relationships among 96 accessions collected from a wide geographic range. Genetic distances, marker frequency, and marker diversity were used to compare subpopulations of these accessions. Differences in RAPD marker frequencies indicated uniqueness of accessions from the New and Old World collections. In addition, accessions from Ecuador, Peru, and Chile had a larger magnitude of marker diversity than do Old World accessions. Comparison of sub‐populations of L. esculentum and its sub‐species, L. esculentum var. cerasiforme, indicated that the two are distinct but have similar levels of diversity. Variation among L. esculentum accessions can be obtained at a faster rate by sampling accessions from the primary center vs. other geographic regions. Yet Old World accessions complement accessions from the New World and are not simply redundant sources of variation.