Is it possible to mendelize the QTLs? When Quantitatitve Traits Behave like Mendelian Ones

In many breeding programs, I’ve seen segregating generations full of potential—but often their trait data gets ignored. And yet, those segregations offer a glimpse into the mode of inheritance, pointing to more strategic breeding decisions.

Understanding the difference between mendelian versus quantitative inheritance is the key. 𝗠𝗲𝗻𝗱𝗲𝗹𝗶𝗮𝗻 𝘁𝗿𝗮𝗶𝘁𝘀 are typically controlled by one or a few genes, show clear segregation ratios (like 3:1 or 1:2:1), and are mostly stable across environments.
A good example is the fruit skin color in tomato, particularly the difference between red and yellow fruit. This trait is primarily controlled by a single gene, the 𝘆 locus.
On the other hand, 𝗾𝘂𝗮𝗻𝘁𝗶𝘁𝗮𝘁𝗶𝘃𝗲 𝘁𝗿𝗮𝗶𝘁𝘀 are controlled by many genes (polygenic), tend to show a continuous range of variation, and are strongly influenced by environmental conditions. Traits like yield, earliness, and drought tolerance fall into this category.

By studying the trait disribution in segregating generations, breeders could:

✅𝗜𝗱𝗲𝗻𝘁𝗶𝗳𝘆 𝘁𝗵𝗲 𝘀𝗲𝗴𝗿𝗲𝗴𝗮𝘁𝗶𝗼𝗻 𝗽𝗮𝘁𝘁𝗲𝗿𝗻𝘀 𝗼𝗳 𝘁𝗿𝗮𝗶𝘁𝘀
Examine whether the trait segregates in Mendelian ratios or as a continuous distribution. This provides insight into the number of genes involved and their effect sizes, helping making predictions and designing the selection strategy.

✅𝗜𝗱𝗲𝗻𝘁𝗶𝗳𝘆 𝗶𝗻𝗳𝗹𝘂𝗲𝗻𝗰𝗶𝗻𝗴 𝗳𝗮𝗰𝘁𝗼𝗿𝘀
Sometimes, a trait that should behave Mendelian appears as quantitative. Environmental stress, varying genetic backgrounds, or interactions between genes (epistasis) might be softening the expression of the trait. Recognizing these modifiers helps in understanding how to stabilize its expression.

✅𝗠𝗲𝗻𝗱𝗲𝗹𝗶𝘇𝗲 𝗤𝗧𝗟𝘀
Once a major QTL is identified, use molecular markers to treat it as if it were a Mendelian gene. Control environmental conditions during selection to enhance its expression. This approach makes selection clearer and more effective, even for complex traits.

🔬 𝗖𝗮𝘀𝗲 𝗶𝗻 𝗣𝗼𝗶𝗻𝘁: 𝗧𝗼𝗺𝗮𝘁𝗼 𝗤𝗧𝗟𝘀 𝗳𝗼𝗿 𝗬𝗶𝗲𝗹𝗱 𝗮𝗻𝗱 𝗦𝘂𝗴𝗮𝗿

This strategy isn’t just theoretical—it’s already delivering results in real breeding programs. By identifying major QTLs and managing them through molecular tools and targeted environments, breeders have successfully transformed complex traits into more manageable ones.

One compelling example comes from tomato breeding, where researchers used markers linked to three major QTLs to create tomato lines with better yield and flavor. By “mendelizing” these QTLs, they turned a complex quantitative trait into a more predictable and selectable one.

🔗 https://lnkd.in/dHXFHsCn

📣 So, what about your breeding program? Are there QTLs that you could mendelize?