Adapting to the enemy: Rice yellow mottle virus (RYMV) evolutionary dynamics and durable resistance in African rice

Rice yellow mottle virus (RYMV) is one of the most destructive viral diseases affecting rice production in sub-Saharan Africa (SSA), where increasing demand and persistent yield gaps continue to compromise food security. RYMV shows significant genetic and phylogeographic diversity across SSA, driven by mutation, recombination, selection, and restricted regional spread, enabling adaptation to host resistance. The main resistance genes, RYMV1, RYMV2, and RYMV3, primarily derived from Oryza glaberrima, differ in their molecular mechanisms and the selective pressures they impose on viral populations. Resistance breakdown linked to RYMV1 primarily stems from mutations in the viral VPg protein, whereas resistance mediated by RYMV2 and RYMV3 is overcome through changes in the P2a polyprotein and coat protein (CP), respectively. An evolution-informed framework combining viral phylogeography, resistance-breaking pathways, and breeding deployment strategies is proposed to explain regional variation in resistance durability and enhance long-term resistance management. Currently, using marker-assisted pyramiding of complementary resistance genes is the most promising and scalable strategy for achieving durable resistance, while genomic selection provides opportunities to improve both quantitative and background resistance. Sustainable management of RYMV will require region-specific deployment of resistant varieties, continuous surveillance of viral populations, integration of quantitative resistance, and better seed system management to reduce selection pressure and virus spread. Emerging technologies such as genome editing and artificial intelligence-assisted breeding may further expand the resistance toolbox but require careful integration.