Co-Location of QTL for Vigor and Resistance to Three Diseases in × Rootstocks.

A QTL on chromosome 4D of the × genome that co-located resistance against , and disease scores was investigated for additional traits. Phenotypic data for counts and tree height were analyzed in this study for the same hybrids previously used to identify this QTL. Using the same GBS genotype data, the same co-located QTL for and spp. disease scores were reproduced and the QTL for counts and tree height were co-located with resistance to and spp. Moreover, we found GBS genotype data to harbor additional genetic variation unrelated to any of the traits analyzed. Marker-assisted and genomic selection models were created and assessed for their performance in selection. The ability to predict traits using SNP data was strongest with two-year tree height, followed by disease score, three-year tree height, spp. disease score, and counts. These results suggest a shared mechanism of action that links disease to tree height. Moreover, deploying these selection models would assist efforts in walnut improvement for rootstock genotypes.