Inheritance for resistance to leaf curl [Taphrina deformans (Berk.) Tul.] in peach cultivars estimated by exploring mixed models

In the present study, the genetics of susceptibility to peach leaf curl, a worldwide disease that affects both crop yield and plant longevity, was investigated using a progeny 'Dofi-84.364' that is highly resistant to the agent Taphrina deformans, as well as 8 cultivars and 2 selections obtained at the University of Florence. Heritability and combining ability were estimated by comparing parent and offspring leaf curl scores of 20 families. The broad-sense heritability of the trait was high (H-Cullis (2) = 0.65). Variance components of the general (GCA) and specific (SCA) effects showed that in the genetic determination of this trait both additive parental effects and interactive effects are important. However, the magnitude of SCA was lower than GCA possibly indicating a preponderance of additive genes controlling susceptibility to leaf curl disease. As expected, the resistant selection 'Dofi-84.364' proved to be a donor of low susceptibility to leaf curl in peach. Progeny tests are relevant to improve the chance to obtain genotypes less susceptible to leaf curl disease. In this trial, both additive and non-additive genetic effects were found to be important, with a greater contribution of additive effects to total genetic effects. Consequently, there may be a good opportunity to advance in T. deformans tolerance by crossing cultivars that have been selected for their phenotypic value and not only for their combining ability.