A strawberry Multi-parent Advanced Generation Intercrosses (MAGIC) population, derived from crosses using six strawberry cultivars was successfully developed. The population was composed of 338 individuals; genome conformation was evaluated by expressed sequence tag-derived simple short repeat (EST-SSR) markers. Cluster analysis and principal component analysis (PCA) based on EST-SSR marker polymorphisms revealed that the MAGIC population was a mosaic of the six founder cultivars and covered the genomic regions of the six founders evenly. Fruit quality related traits, including days to flowering (DTF), fruit weight (FW), fruit firmness (FF), fruit color (FC), soluble solid content (SC), and titratable acidity (TA), of the MAGIC population were evaluated over two years. All traits showed normal transgressive segregation beyond the founder cultivars and most traits, except for DTF, distributed normally. FC exhibited the highest correlation coefficient overall and was distributed normally regardless of differences in DTF, FW, FF, SC, and TA. These facts were supported by PCA using fruit quality related values as explanatory variables, suggesting that major genetic factors, which are not influenced by fluctuations in other fruit traits, could control the distribution of FC. This MAGIC population is a promising resource for genome-wide association studies and genomic selection for efficient strawberry breeding.

We devised a method to evaluate anthracnose disease resistance that can generate highly accurate results on a small-scale basis in a relatively short period of time. Aseptically-sown strawberry seedlings were clonally multiplied on medium containing a cytokinin. After acclimation, resistance to anthracnose disease was evaluated by spray inoculation with Colletotrichum gloeosporioides (Glomerella cingulata) at a concentration of 1 × 10 4 spores・mL -1. This approach allows the evaluation of resistance within approximately 120 days after seeding, with accuracy equivalent to that of the existing method using runner plants. The new method requires no field for inoculation, and so assessment can be completed within a small-scale, closed space such as an acclimation case. Furthermore, susceptible individual seedlings may subsequently be used as materials for genetic analysis, as these plants can be preserved as uninfected clonal seedlings.