Correlation analysis and QTL mapping of fruit quality and plant architecture traits in cultivated strawberry (Fragaria × ananassa)

Understanding the association between phenotype and genotype is essential for plant breeders when selecting for optimal cultivars. However, it is not well known how different traits are correlated at both phenotypic and genotypic level. In this study, correlation analysis and QTL identification of 31 plant characteristics and fruit quality traits was investigated in cultivated strawberry mapping population ('Redgauntlet' × 'Hapil'). Phenotypic data was collected for two consecutive years (2013 and 2014) among six replications using field-grown strawberry plants. The key traits recorded included the attributes of plant growth and development, yield, firmness, sugar level and fruit shape. Phenotypic variations and correlation coefficients were calculated for each trait for both years using R statistical package. The consensus SNP-based genetic linkage map constructed by genotyping IStraw90 Axiom array was used to identify quantitative trait loci (QTL) for the traits recorded. At least a single QTL was identified for all traits recorded. A total of 72 QTLs were identified in 2013 and 90 QTLs were identified in 2014, however majority of them were year-dependent. Only 19 QTLs representing 13 traits were detected for two years. This suggests QTLs are likely to have been affected by environmental factors, and phenotyping traits for the third year are crucial to investigate the consistency of QTLs and to reduce the environmental factors