LOS BAÑOS, THE PHILIPPINES — IRRI is working to provide solutions to problems such as bacterial blight that negatively affect rice production.

According to IRRI, in irrigated environments, bacterial blight can easily spread to large areas, causing up to 30% losses, a huge impact on the income for smallholder farmers in Asia.

“Major genes for resistance called Xa genes (e.g., Xa4, Xa5, Xa21), have already been used in rice breeding programs,” IRRI said. “However, despite the importance of these genes in controlling the disease, the bacteria adapted to these resistant varieties making them susceptible again. There is a need to continue discovering new ways and developing varieties that can protect farmers from losses due to bacterial blight.”

In a recent paper published on PLOS, scientists discovered variations of SWEET genes that make the plant resistant to Xanthomonas oryzae pv. Oryzae, which causes bacterial blight.

“In normal conditions, the pathogen promotes the leakage of sugars by activating SWEET genes inside the plant cell,” said Ricardo Oliva, senior scientist on plant pathology at IRRI. “However, the new SWEET gene variants prevent sugar to be released. As a result, the bacteria fails to get nutrition from the host plant and it eventually dies.”

The gene naturally occurs in rice.

“Using IRRI’s rich germplasm collection, we were able to discover the potential of variations in the SWEET gene to be used in breeding new blight-resistant varieties,” Oliva said. “The variations appear to have emerged from at least three rice subspecies. This opens up the gates to use similar techniques to fight other pathogens in rice as well as in other crops such as corn, wheat, and cassava.”

At present, this is already part of IRRI’s breeding pipeline and is expected to be available for use in a few years.