# Development of a Flex-Seq SNP panel for raspberry (Rubus idaeus L.) and validation through linkage map construction and identification of QTL for several traits of agronomic importance to raspberry breeding

## TL;DR

This paper introduces a custom SNP panel for red raspberry, enabling genetic mapping and identification of traits important for breeding.

## Contribution

A high-confidence SNP panel for raspberry was developed and validated for linkage mapping and QTL identification.

## Key findings

- A 5,639 SNP panel was created for red raspberry, covering all seven chromosomes.
- QTLs for fruit size, leaf color, plant vigour, and thorn density were identified.
- A major QTL for thornlessness co-located with a HOX3 gene on chromosome 4.

## Abstract

High-throughput and reproducible genotyping platforms are critical for advancing genetic research and breeding in horticultural crops. Here, the development and validation of a custom single nucleotide polymorphism (SNP) panel using the Flex-Seq genotyping platform for red raspberry (Rubus idaeus L.) is described. SNPs were derived from existing linkage maps and RNA-seq data, resulting in a panel of 5,639 high-confidence, bi-allelic markers distributed across the seven chromosomes of the R. idaeus ‘Malling Jewel’ reference genome. The panel was used to genotype 457 red raspberry accessions including 161 individuals from a bi-parental mapping population (Paris×486), enabling the construction of high-density linkage maps and the identification of quantitative trait loci (QTL) for fruit size, leaf colour, plant vigour, and thorn density. Genome-wide association studies (GWAS) identified a major QTL for thornlessness on chromosome 4, co-locating with a candidate HOX3 gene, and multiple QTLs associated with anthocyanin biosynthesis genes for leaf colour. The SNP panel demonstrated utility for linkage mapping and trait association analyses, offering a powerful resource for marker-assisted selection and genetic improvement in red raspberry.