Welcome to our blog series about Plant Breeding!
Imagine a world in which our crops had superpowers, such as the ability to withstand pests and diseases, thrive in harsh and hostile environments, and still produce high yields and good qualities. In our first episode of 'Adventures and Challenges in Plant Breeding', we are taking a glimpse at how to develop crop superheroes of tomorrow by first understanding the complexity behind every breeder's challenge: complex traits.
Understanding Complex Traits
Imagine you are trying to create the 'perfect' crop that has a high value to society, a crop that is more productive using fewer resources, like water, fertilizers, and pesticides every year. You want these crops to be high-yielding, high-quality, and adaptable to the environment in which they are growing. Each of these characteristics represents a trait. And not all traits are created genetically the same. Some are simple, such as plant height, kernel color, or hardness, controlled by a (few) single gene(s) and changed little by the environment. Their inheritance is straightforward, their expressions are simply classified, making selection easy. And where there are simple traits, there must be others, too. Complex traits are characteristics that are impacted by a number of genes and environmental factors, making it difficult to detect the effects of each gene, and to categorize them. Complex traits include yield, attributes contributing to yield, or economically important qualities such as protein content.
Here are some of the challenges that breeders face when working on complex traits:
Complex Traits, Selection, and Selection Gain
Breeding for complex traits can be like putting together a 1000-piece jigsaw puzzle in the dark. The better we understand the different types of pieces and how they fit together, the more efficiently and quickly we can complete the puzzle. We determine the selection gain in breeding to judge our success in putting the 'puzzle’ pieces together. Selection Gain indicates how much we have enhanced a trait over the course of a single generation or breeding cycle.
What is the relationship between traits and selection gain? Let's say you have a field of wheat, and you want to develop a dwarf variety (plant height = simple trait). You easily select the plants that are very small. You will notice a significant improvement right away (high selection gain) because dwarfism is simply inherited. Think of breeding for a simple trait as doing a children's puzzle on a sunny day. It's quick, and the progress is immediately noticeable.
This looks different for yield, where you will see an improvement only over a longer period of time. Breeding for complex traits may be gradual. The process of understanding complex traits is like turning on a dim light in the dark room where you are working on the 1000-piece puzzle. The brighter the room becomes, the more efficiently and strategically you are able to place each piece. Nevertheless, you still have to focus on piece after piece, and that takes time.
Let’s look at the drought tolerance “puzzle” in plants. In order to improve drought tolerance, we have to look at several subtraits such as root architecture and depth, water use efficiency, cuticula thickness, leaf area index, and photosynthetic rate. Breeders would have to improve them all, which might seem subtle initially. Yet, over time, as they methodically refine each trait, the entire picture of drought resistance becomes clearer, showing the cumulative impact of their efforts.
Solutions to Creating Crop Superheroes
So, how do we reveal crops with the best performance for complex traits? Here are some key strategies:
Understanding complex traits is achievable now because of developments in technology and tools. This is already boosting the breeders’ selection efficiency and resulting in higher selection gain. The world of plant breeding is a thrilling adventure. Complex traits may be elusive, but we are prepared with knowledge, innovation, and a passion for creating crop superheroes. So, next time you eat a juicy tomato or enjoy a slice of bread, remember that behind every delicious bite lies the brilliance of plant breeding.
Stay tuned for our next Episode, "Genius Genes: Unlocking Genetic Diversity"!
Do you want to know how Computomics can support plant breeding for the future?
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