Accuracy of genomic selection and long-term genetic gain for resistance to Verticillium wilt in a genetically diverse strawberry population

Verticillium wilt, a soil-borne disease caused by the fungal pathogen Verticillium dahliae, threatens strawberry (Fragaria × ananassa) production worldwide.  The development of resistant cultivars has been a challenge since the disease was first reported on strawberry in the early 1900s.  The empirical evidence suggests that genetic gains have not been negligible and that the genetics of resistance to this pathogen is quantitative.  While resistant cultivars have been developed, a comparatively small percentage are highly resistant, whereas a large percentage are moderately to highly susceptible.  To develop insights into the genetics of resistance, we studied a population of elite and exotic germplasm accessions (n = 984), including 245 cultivars developed in public breeding programs since 1854.  We observed a full range of phenotypes, from highly susceptible to highly resistant.  Broad-sense heritabilities ranged from 0.70 to 0.76, whereas narrow-sense genomic heritabilities ranged fr...