Marker-assisted simultaneous but stepwise backcross breeding for pyramiding blast resistance genes Piz5 and Pi54 into an elite Basmati rice restorer line ' PRR78'.

Marker-assisted simultaneous but stepwise backcross breeding ( MASS- BB) was utilized in the present study for pyramiding blast resistance genes, Piz5 and Pi54, from non-Basmati donors, C101A51 and Tetep, respectively, into PRR78, an elite Basmati restorer line of rice hybrid, Pusa RH10. Marker-assisted foreground selection coupled with stringent phenotypic selection and background analysis was carried out for hastening the recovery of recurrent parent phenome ( RPP) and genome ( RPG) in two separate backcross series to produce BC₂F₁ plants with individual blast resistance gene. The best BC₂F₁ plant from each backcross series was intercrossed, and the resultant F₁ was selfed to pyramid both blast-resistance genes into PRR78. The plants homozygous for both the genes in the F₂ were advanced through pedigree selection to produce superior blast-resistant F₅ lines. Background analysis revealed that the RPG recovery was up to 91.6%. Improved versions of Pusa RH10 developed using the improved PRR78 lines ( PRR78+ Piz5+ Pi54) performed on par with the original Pusa RH10 and showed resistance to blast disease both under artificial screening and at hot spot locations. [ABSTRACT FROM AUTHOR]