Non-Peer ReviewedBased on the projected demand, further improvements in wheat grain yield are required. In this sense, exploring the genetic diversity associated with yield related traits is critical to derive superior progenies from crossing and selection. However, the possible presence of trade-off between traits must be considered to determine their relevance for improving yield potential. In this study, we determined the phenotypic and genetic relationships between twelve spike related traits and their genetic basis through an association mapping study using a 15K Infinium SNP array, characterized in a bread wheat panel. To identify potential candidate genes, regions of interest were positioned onto the newly released wheat reference genome sequence by blasting their peaking marker sequences against the IWGSC RefSeq v1.0. From all the analyzed traits, grain number per fertile spikelet (GFS) showed the highest correlation with grain number per spike (GNS), whereas there was no relationship with thousand kernel weight (TKW). As a result, significant increases in grain weight per spike (GWS) associated with higher GFS was observed. Interestingly, GFS was mostly explained by spikelet weight (SW), indicating that improvements in yield potential could be achieved through partition improving within the spike. In addition, the genetic analysis showed independent genetic control between GFS and both, GNS and TKW, suggesting the potential value of GFS as selection criterion to increase yield potential in wheat breeding programs. A total of 54 significant marker-trait associations were detected for spike related traits, including two genomic regions on 1B and 7A linked to GFS and 6 genomic regions located on 1A, 1B, 2B, 3A, 5A and 7B associated to SW. The potential candidate genes for these regions included several sugar transporter and carbohydrate-binding protein. The markers linked to GFS and SW are really promising, especially considering that due to the destructive phenotypic determination, their improvement in early breeding generations can only be made by marker-assisted selection
