Evaluation of Submergence Tolerant Improved Restorer Lines for Fertility Restoration and Phosphorus Use Efficiency Using Gene-specific Markers in Rice (Oryza sativa L.)

Restoring fertility in hybrid rice to maximize yield potential mainly involves identification and utilization of fertility restorer (Rf) genes. Thirty-two backcross inbred lines (32 BILs) derived from KMR-3R and Swarna-Sub1 possessing Sub1 generated through marker-assisted backcross breeding (MABB) were screened using Rf4 and Rf3 markers during Rabi-2021. 13 BILs showed both Rf4 and Rf3 alleles, indicating significant variation in marker distribution. Remarkably, the BILs TCP2, TCP10, TCP11, TCP12, TCP14, TCP15, TCP18, TCP23, TCP25, TCP26, TCP28, TCP32, and MB44 were identified as promising restorers possessing both Rf4 and Rf3 genes along with Sub1. Additionally, the BILs TCP11, TCP14, TCP23, TCP28, TCP32, and MB44 were screened for the presence of Pup1 and noted positive for Sub1+Rf4+Rf3+Pup1 (both K46-1 and K46-2). This study demonstrates the combination of Rf4, Rf3 and Pup1 genes in Sub1 introgressed restorers can be used for developing submergence tolerant hybrids under phosphorous deficient soils and flood prone eco-systems.