University of Delaware
delware environmental institute

UD researcher battles rice blast disease to protect food supply

UD researcher battles rice blast disease to protect food supply

A University of Delaware scientist is waging an important battle to help protect a major resource in the world's food supply from a devastating fungal disease known as rice blast.

Nicole Donofrio, assistant professor in the Department of Plant and Soil Sciences at the University of Delaware, said rice blast disease affects foods that many developing countries depend on, such as rice, as well as other members of the grass family including rye, wheat and barley.

Donofrio explained that this disease is particularly destructive, saying, “The general statistic is that rice blast kills enough rice each year to feed 60 million people -- a number we definitely cannot afford, particularly in the face of the rapidly expanding world population.”

Her work focuses on the complex nature of the interactions between the plants and fungal plant pathogens in trying to understand how certain fungi take advantage of a plant's “inner workings” to grow and reproduce.

The difficulties in finding a solution to rice blast are many, Donofrio said, beginning with the problems that arise in trying to control the disease.

“Applying fungicides over broad expanses of rice fields or paddies is neither economic nor environmentally friendly,” she said.

Because of this, people who grow rice rely on both fungicides and what is known as host resistant -- strains of crops developed to resist the disease -- to stop the fungus.

But Donofrio said the rice blast disease evolves quickly and can overcome these host resistances, as well as the fungicides.

“Typically, a resistance line of rice only lasts a couple years out in the field before the fungus' genome changes to overcome this resistance, and infects its host once again,” she said.

Rice blast disease is caused by a fungus known as Magnaporthe oryzae. This fungus asexually produces spores that infect the plant by landing on the surface, creating a little tube that runs along the surface of the plant and eventually creates a penetration structure.

According to Donofrio, “This specialized structure is called an appressorium, and has been extremely well-studied. Without the appressorium, the fungus cannot attack the plant.”

When the fungus gets inside the plant, it sucks the nutrients out of the plant cells and “eventually, after maybe about 4-5 days, lesions, or dead zones, appear on the rice leaf in a diamond-shaped form,” she said. “These disease symptoms give the disease its name, 'rice blast,' because the leaf eventually looks like it's been 'blasted' with some sort of gun.”

The disease is also very flexible and can infect pretty much any part of the plant, including its roots.

One of the worst ramifications of the disease, according to Donofrio, is “decreasing the amounts of rice to feed an increasing world population” as “many developing countries rely on rice as a staple food crop and without a cure for the disease, hunger concerns worldwide could very well increase.”

Donofrio said she has been interested in researching ways to keep plants healthy since her doctoral studies at Cornell University and decided to focus on this part of plant pathology for her post-doctoral research at North Carolina State University.

“Not to geek out or anything, but I pretty much fell in love with the fungi,” Donofrio said.

Though the disease itself is a devastating one, the study of the disease reaps rewards for Donofrio, who said, “I love watching my lab personnel get really into their projects; it is so rewarding to witness how excited my students get when they make a new discovery, get a new technique to work, or just get a good result.

“It is very exciting to be in such a challenging and important field of research. I am lucky to have had the opportunities and mentors I have thus far had in this field, and to be a part of such a vibrant research community.”

Donofrio said she understands her students' excitement level, having been a student studying the disease herself, but she also understands the importance of continued study to try to find a cure for this harrowing disease.

Article by Adam Thomas