A plant defense gene isolated by University of Arkansas Division of Agriculture scientists has been used to grow a rice plant that kills blast, one of the most serious diseases threatening Arkansas' rice crop.

“The plant tissue dies around the infected area, robbing the fungus of what it needs to live and grow, and sparing the rest of the plant,” said Yinong Yang, molecular biologist in plant pathology for the Arkansas Agricultural Experiment Station. “Our goal is to learn how to develop transgenic plants, like these, that breeders can use to develop new varieties with improved disease resistance.”

Yang modifies the expression of these genes by using DNA sequences called “promoters” to turn defensive responses on constantly or cause a rapid activation when a plant is infected.

“We use specific promoters to activate a defensive response earlier and stronger than normally occurs,” he said. “A plant that responds to an infection within a couple of hours instead of a couple of days gains an important advantage in disease resistance.”

He uses a tissue culture transformation process to introduce the modified genes back into rice plants. These transgenic plants are infected with pathogens, then growth of the disease and disease symptoms are precisely measured.

Yang has identified nearly 200 genes that may control disease resistance in rice and other agricultural plants, he said.

“We're working with five of the genes we've identified to determine their role in blast resistance,” he said. “We're also going to study their effects on plant defenses against bacterial panicle blight and sheath blight.”

Until recently, Yang had to study the genes one at a time to learn their defense responses to pathogen infection. It was a painstaking process necessary to help him understand the molecular mechanisms of disease response in plants. Now, a DNA microarray facility in the University of Arkansas' Core Molecular Lab can help speed up the analysis.

“Microarrays are collections of hundreds or thousands of genes — in this case, defense-related — arranged on a single glass slide,” he said.

“This equipment allows us to examine how all these genes respond to a particular pathogen.

“These genes may be active during resistance responses to many diseases,” Yang said.

“Our research, aided by this technology, can help us develop novel strategies for disease control for rice and other important agricultural crops.”