Researchers at the Panhandle Research and Extension Center are hard at working trying to create disease resistant plants. The latest project targets fuscans blight, a pathogen that is similar to common blight.
Although it isn’t a new pathogen, fuscans blight is largely unknown, Bob Harveson said, a plant pathologist for the University of Nebraska Lincoln.
Harveson is working with Carlos Urrea, a dry edible bean breeding specialist, to study the pathogen and hopefully develop cultivars that are resistant to it.
“Cultivar is another word for variety, basically,” Harveson said. “It’s one that would be sold and that growers would use.”
Some cultivars are agronomically superior, others are more resistant to certain disease. In this case, the idea is to develop a cultivar that is not only resistant to fuscans blight, but that also has agronomic factors that will help it be more successful commercially.
Unfortunately, producers can’t expect that cultivar to be on the market any time soon — the research and development process is a long one and it is only just beginning.
While Urrea has been making progress with cultivars that are resistant to other diseases, such a wilt, his work with fuscans blight began this year when he was awarded funds from the Nebraska Department of Agriculture Specialty Crop Block Grant Program. Funds from the Nebraska Dry Bean Commission were also awarded to the project.
In 2017, Urrea had discovered the disease on some of his plants. He and Harveson isolated the pathogen and froze some of the cultures so they could begin research as soon as funds were available for the project.
The first step is determining whether or not the symptoms a plant is displaying comes from fuscans blight. In order to do that, researches must replicate the symptoms using the pathogen.
One the pathogen is separated, the plants are inoculated with it.
“Bacteria has a hard time getting into a plant without help, so they usually need some kind of wound or an opening,” Harveson said.
Urrea uses a device that punctures the leaf, leaving several tiny holes in it. This allows the bacteria to work its way into the plant.
“Then we watch it,” Urrea said.
“He watches it every hour,” Harveson added. “Sometimes he gets real nervous.”
The most recent test took longer than expected. Usually, symptoms can be observed in four or five days, Urrea said, but it had been nearly 10 days and they didn’t see anything.
“I thought maybe something was wrong with our pathogen,” Harveson said. “I think it had to do with the weather. It’s cool and the days are getting shorter.”
Thankfully though, the space around the holes that were punched in the leaves began turning brown. The plant was successfully infected and displaying the symptoms they expected, meaning they managed to successfully isolate the correct pathogen.
After the plant becomes symptomatic, the pathogen is isolated and purified again. In order to re-isolate the pathogen, symptomatic plants are placed into a humidity chamber. The wet conditions created in the chamber cause the pathogen to begin oozing out of the plant.
Once symptoms are successfully replicated, the researchers can move on to testing the pathogen on other plants, including varieties that may have genes that make them more resistant to some diseases.
“The problem is when you do find a plant with resistance to a disease, a lot of times it isn’t acceptable for commercial production,” Harveson said.
For example, while it may be able to resist blight, the plant may be too small for it to be a viable commercial option.
“Then you have to try to breed the genes in for the higher yields, bigger size, all that kind of stuff,” Harveson said. “So, even if Carlos finds the resistance, the story is not over. The task is not over.”
Over time, Urrea will create multiple generations of the plant — and hopefully each one will be able to better resist the pathogen, although that is not always the case. Unless genes are being mapped very carefully, it’s impossible to know whether a trait will appear the next time around.
“There’s a chance you’ll breed these plants and you don’t even get that benefit in a generation,” Harveson said.
This can be frustrating, because each generation takes upwards of 90 days to grow before the testing process can even begin, Urrea said.
“In order to have something that has commercial value, it could take eight, nine, 10 years,” Urrea said.
If a fuscans blight resistant bean is created, Urrea’s work isn’t finished.
“There will be another one he has to create,” Harveson said. “This is just one disease.”