Strawberry fruit shape: quantification by image analysis and QTL detection by genome-wide association analysis

Area of Science:

• Plant genetics and breeding
• Agricultural science
• Computational biology

Background:

• Fruit shape is a critical trait for cultivated strawberry (Fragaria × ananassa Duch.) breeding.
• Quantitative evaluation of fruit shape is essential for identifying associated genomic regions.
• A multi-parent advanced-generation inter-cross (MAGIC) strawberry population was previously established.

Purpose of the Study:

• To develop and apply a quantitative method for evaluating strawberry fruit shape.
• To identify genomic regions (quantitative trait loci or QTLs) controlling strawberry fruit shape.
• To support marker-assisted selection for improving fruit shape in strawberry breeding programs.

Main Methods:

• Generated 2,969 two-dimensional digital images of strawberry fruits.
• Quantified fruit shape using Elliptic Fourier Descriptors (EFDs) and calculated principal component (PC) scores.
• Performed genome-wide association studies (GWAS) using PC scores as phenotypes and mixed linear models.

Main Results:

• PC1-PC3 effectively captured 96% of the variation in strawberry fruit shape.
• GWAS identified two significant quantitative trait loci (QTLs) associated with fruit shape.
• The developed method provides a robust approach for analyzing fruit morphology.

Conclusions:

• A novel and effective method for analyzing strawberry fruit morphology was established.
• The identified QTLs offer valuable targets for marker-assisted selection in strawberry breeding.
• This research facilitates the genetic improvement of fruit shape in cultivated strawberries.