Wild Crop Relatives: Genomic and Breeding Resources

Abstract

Beet is classified taxonomically as Dicotyledoneae, Caryophyllidae (Centrospermae), Amarantheaceae (formerly Chenopodiaceae), Beta vulgaris L. Linneaus recognized one wild and two cultivated types (table and foliage), which have been domesticated since the earliest beginnings of agriculture (Ford-Lloyd and Williams 1975). The genus Beta comprises four sections and 12 well-defined species; Beta (formerly Vulgares), Corollinae, Procumbentes (formerly Patellares), and Nanae, represented by a single species endemic to Greece. With the exception of Section Beta, species of other sections have a more limited geographic distribution, and are found on European islands of the Atlantic Ocean and coastal and inland locations from Greece to Iran (Ford-Lloyd and Williams 1975; de Bock 1986). The wild taxa within the genus Beta are an important genetic resource for disease resistance breeding of cultivated beet, in particular B. vulgaris subsp. maritima, the closest wild relative. This subspecies is common along the Mediterranean coastline and the central and northern Atlantic coasts of Europe and to a lesser extent inland. Dissemination of its seed may often be by ocean currents because the fruit is buoyant and most extant wild populations are found within 10 m of mean sea level (Doney et al. 1990; Fievet et al. 2007).