# Genome-wide association study of exotic Fragaria germplasm accessions for resistance to Phytophthora crown rot in strawberry

## TL;DR

This study identifies a genetic marker linked to resistance against a major strawberry disease, helping breed more resistant varieties.

## Contribution

A genome-wide association study identifies a key genetic marker and candidate genes for Phytophthora resistance in wild strawberry accessions.

## Key findings

- A single genetic marker on chromosome 7B explains 53% of phenotypic variation in resistance to Phytophthora cactorum.
- Several candidate resistance genes were identified near the significant marker in a 2 Mb genomic region.
- Highly resistant exotic Fragaria accessions could serve as donors for breeding crown rot-resistant cultivars.

## Abstract

The soil-borne oomycete Phytophthora cactorum causes crown rot, a major disease of the allo-octoploid strawberry (Fragaria × ananassa Duch., 2n = 8× = 56) that limits cultivation worldwide. Resistance to P. cactorum is a highly desirable trait but is typically quantitative and moderately heritable. A better understanding of the genetic basis of resistance to crown rot is essential for developing durable crown rot-resistant cultivars.

We conducted a genome-wide association study (GWAS) using multi-locus models on 100 wild strawberry accessions from South and North America. The accessions were genotyped using the Axiom™ 50 K strawberry SNP array and mapped to the F. × ananassa cv. Royal Royce v. 1.0 reference genome. Testing for resistance to P. cactorum revealed a wide range of phenotypes. A single genetic marker, AX-184528282, located on chromosome 7B, was strongly associated with resistance to P. cactorum and explained 53% of the observed phenotypic variation. This marker was present in several highly resistant exotic Fragaria accessions that represent potential donors for introgression of favorable alleles into modern strawberry cultivars. In addition, several strong candidate resistance genes were identified within the 2 Mb genomic region surrounding the significant marker.

This study advances understanding of resistance to P. cactorum in strawberry and identifies genetic resources that can accelerate the development of crown rot-resistant cultivars through marker-assisted breeding.

The online version contains supplementary material available at 10.1186/s12870-026-08186-6.