Novel Gene Promises Durable Resistance Against the Dreaded Rice Blast

Scientists from Japan have pinpointed a gene that helps rice plants resist the dreaded blast disease. Having this gene in high yielding but disease susceptible varieties could help feed millions more people.

A Global Problem

Rice is life for more than half of the world's population. It is the second most widely grown cereal in the world, next to wheat. The crop was planted in more than 155 million hectares in 2008. Around 2.5 billion people in Asia, mostly from developing countries such as India, China, Indonesia and Bangladesh, obtain more than 70 percent of their caloric intake from rice and its derived products. In addition, more than a billion households in Asia, Africa and America, depend on rice for their main source of livelihood.

The global rice production, however, is faced with numerous challenges. According to the United Nations Food and Agriculture Organization (FAO), diseases, insects and weeds are responsible for yield losses of up to 30 percent. The blast disease is one of the most serious and widespread diseases of rice. Caused by the fungus Magnaporthe oryzae, the disease is capable of wiping out entire rice fields. Most rice cultivars are susceptible to the rice blast.

In Japan, as much as 200,000 tons are lost annually to the disease, according to Dr. Shuichi Fukuoka, a scientist at the country's National Institute of Agrobiological Sciences.

A Moving Target

Magnaporthe oryzae is no easy target. Numerous researchers have identified genes that provide resistance against blast. But the pathogen can easily evolve resistance against these genes. What's more, rice cultivars equipped with these genes are usually inferior in terms of agronomic performance.

Recently, a team of Japanese researchers led by Shuichi Fukuoka identified a novel gene that promises longer lasting resistance against the blast-causing fungus. The gene, pi21, encodes a proline-rich protein with putative heavy metal-binding domain and putative protein-protein interaction motifs. It was traced to a Quantitative Trait Locus (QTL) in a blast resistant rice cultivar that has long been grown in Japan. The cultivar, however, is unpopular because it produces lower quality rice.

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