Identification of consensus regions associated with shoot biomass production in the <em>Medicago</em> genome

International audienceIdentification of common genome regions influencing biomass production in multiple Medicago populations can establish focal points for implementing future marker-assisted breeding approaches to improve alfalfa (M. sativa L.) forage yield and facilitate identification of candidate genes. The goal of this study was to identify consensus regions associated with biomass production and candidate genes within the context of the M. truncatula Gaertn. genome, based on previous reports of 83 biomass-affiliated markers and 30 quantitative trait loci (QTL) detected among one M. truncatula and four M. sativa biparental and association mapping populations. The genome positions for 68 markers and all 30 biomass QTL were determined. Ten consensus regions associated with Medicago forage yield in two or more populations were identified. The level of resolution for these regions, however, was not sufficient to clearly identify potential causal candidate genes. Consequently, a targeted set of 208 loci influencing Arabidopsis growth and development were surveyed for their positions in the Medicago genome to identify those which colocalized with biomass markers and QTL intervals. Among 233 homologous genes identified, 51 were located within consensus biomass regions. Potential genes affecting Medicago forage yield variation included those affiliated with phytohormone biosynthesis, transport, and signaling; light responsive developmental phase transitions; and microRNA-mediated regulation of gene expression. These outcomes provide insight into genetic factors that researchers may wish to target for future validation experiments, and for designing marker-assisted breeding strategies to improve alfalfa productivity