Combining ability analysis in 10 strawberry genotypes used in breeding cultivars for tolerance to verticillium wilt

Abstract

General combining ability (GCA) and specific combining ability (SCA) effects of 10 strawberry (Fragaria ×ananassa) cultivars (Darselect, Selvik, Elianny, Figaro, Sonata, Susy, Salsa, Albion, Charlotte, and Filon) for severity of verticillium wilt (Verticillium dahliae) were estimated. Progeny consisting of 45 F1 full-sib families from the crosses made in a half diallel mating design according to the IV Griffing's method was evaluated in two field experiments conducted in 2009 and 2010 on a soil heavily infested with V. dahliae inoculum. Each hybrid family was represented by 60 seedlings (four replicates of 15 plants each). The analysis of variance revealed significant (P < 0.01) GCA and SCA effects of the parental cultivars for the verticillium wilt severity in plants. This suggests that genetic additive and non-additive effects are involved in the inheritance of strawberry tolerance to verticillium wilt. In 2009, a significant negative GCA effect (P < 0.05) for the verticillium wilt severity in plants was found in 'Selvik', 'Filon', and 'Sonata', indicating genetic transmission of tolerance from parents to the offspring. On the other hand, a significant (P < 0.05) and positive for the verticillium wilt severity GCA effect was found for 'Figaro' in 2009, indicating the transmission from this parent to its offspring relatively high susceptibility to the wilt. Only in one hybrid family, 'Albion' × 'Charlotte', was the SCA effect significantly positive (P < 0.05) for verticillium wilt severity in plants, whereas two other hybrid families-'Selvik' × 'Salsa' and 'Sonata' × 'Albion'-showed significantly negative SCA effects (P < 0.05). Three of 10 evaluated genotypes (i.e., 'Selvik', 'Filon', and 'Sonata') were found to be the most valuable parents to the strawberry breeding program for tolerance to verticillium wilt. The least suitable cultivar for this purpose was 'Figaro'.