A study conducted by Embrapa Recursos Genéticos e Biotecnologia (DF) has utilized gene editing technology through the CRISPR/Cas9 technique to confer resistance to rice blast disease in the BRSMG Curinga rice cultivar. Originally launched in 2005, the BRSMG Curinga was replaced in the market after losing its resistance to the disease caused by the fungus Magnaporthe oryzae over the years. This technology, which resulted from the knockout of two target genes related to rice blast disease, is still in the testing phase but has the potential to reach the market in a few years.

According to researcher Angela Mehta, cultivars like BRSMG Curinga, initially introduced to the market as resistant or tolerant to rice blast disease, become susceptible after a few years due to the high variability of the fungus. This poses a problem for both rainfed and irrigated rice. The study compared a susceptible genotype of rice with a resistant genotype to identify proteins that become more abundant in the susceptible plant after pathogen infection. “We identified a group of proteins potentially involved in this susceptibility and selected some corresponding genes to knockout using CRISPR,” Mehta explains.

The term “knockout” refers to removing the function of a specific gene, causing it to stop producing the functional protein. Mehta emphasizes the importance of prospecting for genes of agronomic interest using omics techniques, such as genomics, transcriptomics, proteomics, and metabolomics. Three knockout-susceptible genes were identified, two of which were validated during Fabiano Távora’s sandwich Ph.D. under Mehta’s guidance at the Center for International Cooperation in Agronomic Research for Development (Cirad) in France.

By knocking out these genes in the model rice variety Kitaake, Távora observed that the plant became slightly more resistant to rice blast disease compared to the unedited variety. Upon his return from France, one of these genes was targeted, and two others were selected to create a combination of targets for the knockout of two genes simultaneously in two distinct constructs in the BRSMG Curinga cultivar. This study resulted in two strains of rice resistant to rice blast disease, each with mutations in the two target genes.

Mehta notes that these results, obtained in a greenhouse setting, have yet to be challenged with other fungal isolates to verify the sustainability of this resistance. The choice of the BRSMG Curinga cultivar was based on its transformable genotype and agronomic characteristics closer to the producer’s requirements compared to model cultivars like Nipponbare and Kitaake. The research contributes an important source of genetic resistance to rice blast disease for incorporation into elite varieties and breeding populations within the rice breeding program.

The study is being conducted in collaboration with researchers Raquel Mello and Adriano Castro from Embrapa Rice and Beans (GO) under the leadership of Angela Mehta and funded by Embrapa, with the support of an Embrapa-Monsanto project led by researcher Márcia Chaves from Embrapa Clima Temperado (RS).

Com informações da Embrapa
Fotos: Foto: Cláudio Bezerra / Embrapa