Detached leaf assay-based screening of anthracnose resistant wild strawberry genotypes

Abstract

Anthracnose, caused by Colletotrichum spp. is one of the most devastating disease of strawberry. Identification of strawberry resistance to anthracnose has been a priority in strawberry breeding programs. Here, a total of 34 strawberry genotypes were evaluated for resistance to Colletotrichum gloeosporioides using detached leaf assay. Following C. gloeosporioides inoculation, the activities of defense enzymes such as catalase (CAT), peroxidase (POD), superoxide dismutase (SOD), superoxide anion (•O₂⁻) accumulation, and expression of pathogenesis-related 1 (PR1) and plant defending 1.2 (PDF 1.2) genes were examined. Two genotypes were resistant (R), seven moderately resistant (MR), thirteen susceptible (S), and twelve highly susceptible (HS). Fragaria nilgerrensis Schlech. and F. mandschurica were resistant to C. gloeosporioides, while F. vesca ‘Hawaii 4’ and Fragaria × ananassa cv ‘Miaoxiang No. 3’ were highly sensitive to the pathogen. Furthermore, the leaves of F. nilgerrensis, displayed more •O₂⁻ production and cell death than ‘Miaoxiang No. 3’ following pathogen inoculation. The activities of defense enzymes such as CAT, POD, and SOD in F. nilgerrensis and F. mandschurica were higher than in “Hawaii 4” and ‘Miaoxiang No. 3’. Following inoculation, PR1, PR5, PDF1.2, and coronatine insensitive 1 gene showed high expression levels in F. nilgerrensis, F. mandschurica, ‘Hawaii 4’, and ‘Miaoxiang No. 3’. This work provides insights into the response of different strawberry genotypes to C. gloeosporioides infection in and will help breeders in selecting strawberry germplasm for disease-resistant breeding programs.