I received this question from someone in the audience during my lecture at the Department of Crop Science of the Agricultural University of Athens on February 17.
Since I like to address real questions coming from real breeding and research projects, here’s a step-by-step way to choose the right approach 👇

𝐒𝐭𝐞𝐩 𝟏: Define your breeding goal
Ask yourself:
🔹 Do I want to rapidly develop a robust, diagnostic marker for selection within a specific breeding program?
→ Biparental QTL mapping
🔹 Or do I want to understand the genetic architecture of a trait at the species level?
→ GWAS

𝐒𝐭𝐞𝐩 𝟐: Look at the genetic structure of the trait
✅ Choose biparental QTL mapping if:
– The trait is controlled by a rare gene
(e.g. a disease resistance coming from a unique wild accession)
– The trait segregates clearly between two parents
– You aim to build a Marker-Assisted Selection (MAS) tool for a specific breeding program
👉 QTL mapping offers high detection power, low noise, and fast, clear interpretation.

𝐒𝐭𝐞𝐩 𝟑: Assess your genomic and genotypic resources
✅ Choose biparental QTL mapping if:
– You are working with a new or orphan species
– A high-quality reference genome is missing
– There is limited access to high-throughput genotyping
👉 Controlled crosses can work very well with a moderate number of markers, provided they homogeneously cover the genome.

𝐒𝐭𝐞𝐩 𝟒: Consider population size & diversity
✅ Choose GWAS if:
– You have access to diverse germplasm (e.g. from a gene bank) or a pool of elite breeding liness
– You are studying a complex trait
(e.g. yield, stress tolerance, fruit quality such as Brix in tomato)
– You want to capture multiple alleles across the species
👉 GWAS leverages historical recombination and broader genetic diversity.

𝐒𝐭𝐞𝐩 𝟓: Think ahead to Genomic Selection
✅ Choose GWAS if:
– You are developing or training Genomic Selection (GS) models
– You need genotype–phenotype relationships across many genetic backgrounds
👉 GWAS is often part of the GS data ecosystem, rather than a standalone goal.

Final takeaway
When genotyping resources are limited and the favorable genotype is confined to one or very few lines, biparental QTL mapping provides a straightforward and powerful approach for rapid marker discovery.

👉 If you’d like to be informed about the upcoming workshops organized by AgroSynapsis, and receive early access and discounts, 𝗳𝗶𝗹𝗹 𝗼𝘂𝘁 𝗼𝘂𝗿 𝘀𝗵𝗼𝗿𝘁 𝘁𝗿𝗮𝗶𝗻𝗶𝗻𝗴 𝗶𝗻𝘁𝗲𝗿𝗲𝘀𝘁 𝗳𝗼𝗿𝗺 here:

https://lnkd.in/g3tApqPz

How do I decide whether to use biparental QTL mapping or GWAS for marker discovery?