Resistance reaction of gene introgressed lines against rice blast (Pyricularia oryzae) disease

Blast disease is considered as a major limiting factor in the global rice production because of its wide distribution and destructiveness. Near Isogenic Lines (NILs) harboring different blast resistant Pi genes were surveyed for blast resistance along with resistant and susceptible varieties. These genotypes were randomly crossed to transfer disease resistance to agronomically superior varieties ADT 43, Improved White Ponni and BPT5204. Disease reaction was recorded in both artificial as well as natural epiphytotic conditions and differential response to blast disease incidence was observed. The minimum blast incidence was observed in F1s of ADT 43/CT13432-3R, ADT 43/C101A51 and ADT 43/C101LAC across the environments. Advanced back cross inbred lines developed from the cross combination ADT 43/CT13432-3R were also screened against blast disease. Gene pyramided back cross lines exhibited higher resistance than susceptible genotypes. Among the genotypes tested under epiphytotic conditions at different environments, lines with gene combinations Pi1 + Pi2 + Pi33 + Pi54 and Pi1 + Pi2 + Pi33 were highly resistant to blast disease than those with single genes indicating that these non-allelic genes have a complementary effect. Variation in resistance reaction was observed for the same gene when it acts alone or in combinations and also when the same genes were present in different genetic backgrounds. The gene pyramided lines developed in this study can serve as excellent donors for blast resistance in rice improvement and also for basic studies on gene-race interactions.