Evaluation of Improved drought-tolerant parental lines of KMR3R for fertility restoration by molecular analysis

The present investigation was carried out to identify fertility restoration in improved drought tolerant parental lines with ideal agronomic trait performances and their utilization in the hybrid rice breeding program. Backcross derived lines obtained from a cross between a drought-tolerant Vandana NIL (donor, possessing qDTY12.1 and qDTY1.1) and a drought susceptible restorer, KMR3R (recurrent parent, possessing Rf3 and Rf4 genes). Based on foreground and background selection, the backcross population was advanced to BC2 F4 population by stringent Marker-Assisted Backcross Breeding (MABB). Molecular markers were utilized in the marker assisted restorer selection in WA-CMS from large source of nurseries to keep away from regular test cross nursery (TCN) in the hybrid rice breeding technology. The tightly linked/or gene-specific markers viz., RM6100, RMS-PPR-9-1, DRCG-Rf4-14, for Rf4 on chromosome 10, and DRRM Rf3-10, RM 10313, and RMS-SF21-5 for Rf3 located on chromosome 1 were used to screen for the presence or absence of specific restorer allele in the population. 71 improved drought-tolerant backcross inbred lines (BILs), including checks, and parents were screened for their fertility restoration. Results were skewed in their frequency distribution by showing 48.48% of Rf3 and Rf4 genes (Rf3Rf3/Rf4Rf4). These double allelic combination containing genotypes exhibit better fertility restoration than any of single Rf3Rf3/rf4rf4 or rf3rf3/Rf4Rf4 individually. Ultimately ten genotypes were identified as complete restorers (RP6340 NPVR1, RP6340 NPVR3, RP6340 NPVR10, RP 6340 NPVR24, RP6340 NPVR27, RP6340 NPVR32, RP6340 NPVR48, RP6340 NPVR52, RP6340 NRR5 and RP6340 NRR11) with drought QTLs for drought-prone lowland ecosystems and can be utilized in the hybrid rice breeding Programme under unfavorable drought ecologies