GENE ANALYSIS FOR RICE BLAST RESISTANCE IN INDONESIA

Rice blast caused by the fungus Pyricularia grisea Sacc. is a major constraint to rice production in Indonesia, particularly in areas where environmental conditions are conducive to the disease development. Progression of the rice blast on rice plants involves inoculum initiation, penetration of the pathogen into the plant, infection process, and symptom development.

Improvement of rice for durable resistance rice blast is difficult due to the complexity of inheritance of resistance. A study was conducted by researchers in Indonesian Centre for Agricultural Biotechnology and Genetic Resources Research and Development (ICABIOGRAD), Bogor Agricultural University and Centre of Crops Varieties Protection to analyze the resistance genes on a wild rice Oryza rufipogon Griff. and rice cultivar IR64 using two different approaches, i.e., blast QTL mapping and comparison of resistance spectrum and genetic control.

Result of the experiment showed that based on the blast QTL mapping, genes pirf2-1 (t) and Pir2-3 (t) were mapped on chromosome2. Gene Pirf2-1 was isolated from chromosome 2 of O. rufipogon and coding for resistance to P. grisea race 001, while gene Pir2-3 (t) which was isolated from rice cultivar IR64 was coding for resistance to P.grisea race 173. Based on the resistance spectrum, O. rufipogon has a non-race specific resistance. Gene Pirf2-1 (t) on O. rufipogon contributed a dominant mode of resistance to blast which was affected by a duplicate epistasis. The other gene, pir 2-3 (t) contributed an additive mode of resistance which was affected by a complementary epistasis.

The article “Resistance Genes on a Wild Rice Oryza rufipogon Griff. and Rice Cultivar IR64” can be accessed for subscribers of Jurnal AgroBiogen at http://www.indobiogen.or.id/agrobiogen.php.