Marker-assisted selection in faba bean (Vicia faba L.)

Among the multiple applications of DNA markers in breeding, the most promising for cultivar development is marker-assisted selection (MAS). Genetic improvement by MAS has been carried out with success in several legume crops such as soybean, common bean and pea, however, in other species such as faba bean it is still in its early stages. This article provides an overview of the genomic resources and molecular markers currently available in faba bean, with an emphasis on development and application of MAS for genetic improvement of the crop. In general, genetically simple traits have received more attention than genetically complex characters encoded by multiple genes. Research has mainly focussed on developing molecular markers for selecting resistance to a parasitic weed and other major diseases. As a result, molecular breeding for resistance to crenate broomrape, ascochyta blight, rust and chocolate spot is underway, and promising results have been obtained. Recently, markers linked to a gene controlling growth habit or to select against traits affecting the nutritional value of seeds (tannins, vicine and convicine content) have also been reported, which may facilitate a more efficient selection of new cultivars free of anti-nutritional compounds. In the near future, molecular markers should be developed for many other highly sought-after traits that are difficult to breed conventionally such as frost or drought tolerance. Comparative genomics and synteny analyses with closely related legumes, together with extensive mapping of resistance gene analogs (RGAs), will reveal new candidate genes and selectable markers for use in MAS. Finally genomic tools such as macro- and microarrays may eventually become available for use in faba crop improvement.