The Philippines
December 11, 2025
Rice flowers are dipped in an Agrobacterium suspension to introduce gene edits for tungro resistance.
In a promising development for rice farmers, researchers from the Department of Agriculture–Crop Biotechnology Center (DA-CBC) have successfully used a floral dip-based gene editing technique to boost tungro resistance in NSIC Rc 402, a widely cultivated Indica rice variety.
Tungro, a viral disease transmitted by leafhoppers, causes up to 30% crop loss annually—equivalent to 456,000 tons of rough rice—posing a major threat to the country’s rice production and food security.
According to Dr. Reynante L. Ordonio, the project leader, traditional tissue culture methods for genetic transformation are often inefficient for Indica rice varieties due to their limited responsiveness. “Floral dip offers a simpler, faster, and more practical alternative,” he said.
In this method, rice flowers at the pre-anthesis stage are immersed in a solution containing Agrobacterium tumefaciens, a soil-borne bacterium carrying a CRISPR-Cas9 construct—a gene-editing tool designed to disable the eIF4g gene, which makes the plant susceptible to the rice tungro spherical virus (RTSV). The solution also contains a hygromycin resistance gene, allowing researchers to easily identify successful transformations.
Genetically modified NSIC Rc 402 (left) survives hygromycin treatment (50mg/L), unlike the wild-type variety (right).
From 512 harvested T1 seeds of the floral-dipped NSIC Rc 402, more than 400 grew into healthy plants that survived antibiotic screening. Remarkably, seven lines maintained tungro resistance for three successive generations—showing strong potential for stable resistance inheritance.
“These results demonstrate that the floral dip method can effectively enhance disease resistance not only in NSIC Rc 402 but also in other Indica rice varieties,” Dr. Ordonio noted. “This opens opportunities for faster breeding of improved rice lines with traits for yield, quality, and stress tolerance.”
The team emphasized that the approach could significantly accelerate rice breeding programs, contributing to sustainable agriculture and food security in the Philippines.
“With continued funding support from the DA-Biotechnology Program Office, we aim to further refine and adapt this protocol for more local varieties and even other crops,” Ordonio added.
The innovation marks a major step toward producing tungro-resistant Indica rice—bringing hope to farmers battling one of the country’s most persistent rice diseases.
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