How Good Crop Breeding Impacts Plant Health
January 15, 2024 Crop-breeding companies are in a perpetual dance with disease strains. Just as a new race of Fusarium steps forward, breeders quickly introduce a resistant variety, taking the lead from the disease.
It’s a remarkable feat, considering the complexity of breeding and the time it takes to develop, test, and market a new variety.
We spoke with Enza Zaden’s lettuce breeder, Juan Marroquin Aco, about how he and his colleagues stay a step ahead.
There’s a lot of tension between how quickly diseases develop and the amount of time it takes to breed crops. How do you, as a breeder, respond to that?
Marroquin Aco: Your question is very complex. As we know, breeding takes time. When we are doing a cross between two parents, parent A and parent B, we call the cross created an F1. From that F1 we need to move it to F7, F8, F9.
This is what used to happen many years ago: If we were doing only one cycle a year, that means it will take us seven, eight, nine years to get to a fixed variety that we can bring to the market.
Then it must be introduced. That means testing by the product development team and by the dealers’ sales teams to see if they like the variety. So on top of the time it takes to breed the variety, you will have to add another two or three years. A very complex, very long breeding process.
Today, we are using different techniques like marker assisted backcrossing (MABC). We call it marker assisted selection (MAS).
MAS rapid cycling allows us to shorten breeding time from between eight to 10 years to a much shorter time — between four and six years. But it is still four to six years.
It’s a lot of time when you think about it. And diseases are always coming.
It seems like breeders get varieties resistant to new strains to market quickly, though. How does that work?
Marroquin Aco: It’s because we as breeders can anticipate the evolution of some diseases. Not to say that we have a crystal ball. But we pick all these multiple directions to have in our buckets before a new disease strain emerges.
We also have different resources to develop resistance, like resistance already existing in wild type, or we might even have the resistance in our
own varieties.
Romaine lettuce plant infected with Impatiens Necrotic Spot Virus (INSV).
Photo by John Palumbo
One disease sending shock waves through the leafy green industry is impatiens necrotic spot virus (INSV). We’ve been told it used to be a 1% problem, meaning it affected so few, most breeders did not focus on it. Then it began wiping out crops mid-season in the Salinas Valley. How are you responding to it?
Marroquin Aco: In fact, we at Enza have one variety that has the tolerance to INSV. And the question there is, what does the variety also need? For one, it needs Bremia resistance. So, the variety was a good discovery by our team.
What can we do to accelerate that process using these techniques? But not only that, what we have is the challenge of multiple diseases.
We have Fusarium, Verticillium, and Bremia. And the crop timing matters as well.
If we’re in the spring, maybe the focus is Bremia. Then we find a little more Fusarium coming in. So we need to put our efforts in Fusarium for the spring varieties.
Now we have new sources that we are bringing into our varieties. Testing we did last year showed high resistance to the races that are present in the Salinas Valley. Same for Yuma.
For more of the Q&A, read the full article as part of our special Global Insight Series report on Plant Health.
In addition, check out the previous reports in Meister’s Global Insight Series covering a range of topics from Biocontrol to Irrigation Innovations to Agricultural Technology.
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