USDA: Previously Unknown Rice Blast Resistance Isolated

ARS plant pathologist Yulin Jia samples a field in Colombia for the disease. USDA photo by Fernando Correa.

A gene that gives rice resistance to a disease that has been costing about $66 billion a year in global damage has been isolated by a team of scientists led by U.S. Department of Agriculture’s (USDA) Agricultural Research Service (ARS) plant pathologist Yulin Jia.

Rice blast, caused by the fungus Magnaporthe oryzae, results in annual yield losses large enough to have fed 60 billion people each year, according to the team’s paper published in the journal Nature Communications.

In the U.S. mid-south rice-growing region, the cost of mitigating rice blast infection with fungicide applications can reach almost $20 per acre; plus, the fungus may still cause significant yield loss depending on the susceptibility of each rice variety and the degree of infection at the time of fungicide application, according to the USDA’s Economic Research Service (ERS).

The disease resistance gene, Ptr, has a structure that has not been seen in plants before. It has been previously deployed unknowingly in blast-resistant rice cultivars because it has been tightly linked to another disease resistance gene, Pi-ta, which has a genetic structure that is well-described in scientific literature.

“Our research was able to separate the two genes and demonstrate that Ptr is independently responsible for its own broad-spectrum blast resistance without Pi-ta,” Jia said. “This will provide a new strategy for developing blast-resistant rice cultivars.”

The full genomic sequence of the Ptr gene was put into GenBank for use by public researchers worldwide.

Jia, along with his colleagues Haijun Zhao, Melissa H. Jia and Jeremy D. Edwards, is with the ARS Dale Bumpers National Rice Research Center in Stuttgart, Arkansas, U.S. Other contributors include Xueyan Wang and Yeshi Wamishe at the University of Arkansas Rice Research and Extension Center; Bastian Minkenberg, Matthew Wheatly and Yinong Yang at the Pennsylvania State University; Jiangbo Fan and Guo-Liang Wang at the Ohio State University; Adam Famoso at Louisiana State University; and Barbara Valent at Kansas State University.

USDA's National Institute of Food and Agriculture supported the study with an Agriculture and Food Research Initiative grant.

This article was originally published June 8, 2018, in World-Grain.com.

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