Current Status of Rice Tungro Disease Research and Futurre Program
Entomology and Plant Pathology Division,
International Rice Research Institute (IRRI) has been engaged in the areas of rice tungro disease (RTD) research such as entiological studies of rice tungro viruses (RTV), and development of resistant varieties and preventive resource management strategy. Dozens of germplasm accessions resistant/tolerant to RTV have been identified. Advanced breeding lines derived from such germplasm wereevaluated in multiple locations, and have been released to deploy in RTD endemic regions. Although the deployment of RTV resistant varieties has been effective to control RTD in fields, the genetic resources currently available are still limited and mus be diversified for sustainable management of RTD. In order to facilitate the further diversification of RTV-resistant varieties, genetic and molecular analyses of genes associated with resistance againts RTV are being conducted. Genetic stocks derived from various resistance sources and the IR64 mutant lines selected for RTV resistance are particularly valuable to identify genes involved in resistance as well as to investigate the resistance modes of action through examination of the rice-RTV interactions. Inheritance characteristics of resistantce in several resistant line have already been detemined. Mapping of loci for RTV resistance in the genome of some resistant lines are on going using molecular markers, and the genes associated with resistance are being examined through comparative analysis of gene expression in near-isogenic lines using mirroarray . in addition, it is also imperative to establish appropriate deployment strategies for resistant varieties as well as the monitoring system for pathogenicity of RTV field isolates in order to prolong the life of resistant varieties. The mixed variety planting strategy has been seems to be a promising allternetive to the pure resistant variety deployment, especially to suppress RTD incidence to reasonable level and to stabilize yields in endemic regions.
Key words : Rice tungro disease, research & future program, IRRI