Biodiversity Assessment of Sugar Beet Species and Its Wild Relatives: Linking Ecological Data with New Genetic Approaches

Abstract

The value of crop wild relatives has long been acknowledged and this wild resource has been used to improve crop performance with clear economic benefits. Sugar beet (Beta vulgaris subsp. vulgaris) is the most economically valuable crop species in the order Caryophyllales, B. vulgaris subsp. maritima being the ancestor of the cultivated beets. The wild species of the genus Beta s.l. are commonly found in coastal areas of Europe and Mediterranean Region, where a rich genetic heritage still exists. Broadening the genetic base of sugar beet by introgression with wild relatives is a growing need regarding the maintenance of ecologically important traits. Since wild relatives have adapted to specific habitats, they constitute an important source of novel traits for the beet breeding pool. So, we conducted a broader re-search project aiming to delimit taxa and identify priority locations to establish genetic reserves of the wild Beta species occurring in Portugal (Western Iberian Peninsula). The aim of this study was: 1) to identify and characterize the main habitats of these wild Beta species; and 2) to present a review of some genetic tools available for future application in sugar beet breeding. In this review, we have focused on EcoTILLING as a molecular tool to assess DNA polymer-phisms in wild populations of Beta and identify candidate genes related to drought and salt tolerance, as well as ad-dressed some issues related to next-generation sequencing (NGS) technologies as a new molecular tool to assess adap-tive genetic variation on the wild relatives of sugar beet.