Marker Aided Selection of Yield-enhancing QTL yld2.1 into Restorer KMR3 and Fine Mapping a Genomic Region on Chromosome 2

Yield-enhancing QTLs are becoming major tools in plant breeding, their identification and characterization leads to understanding genes and physiological pathways involved in the complex trait, yield. In previous study ,one major effect QTL (yld2.1) for yield and related traits was identified on chromosome 2 and was mapped to the interval between RM262 and RM263 (21 cM, ~5MB) using an advanced backcross test cross family derived from the cross between IR 58025A and O.rufipogon (IC 22015) accession. We aimed at fine mapping the yld 2.1 for identifying the gene/s responsible for increased yield in restorer line KMR3 background. 55 BC3F3 near-isogenic lines (NILs) representing 960 plants were used in fine mapping of yld2.1 with 8 polymorphic SSR markers. QTL analysis in BC3F3 population using single marker analysis, interval mapping and composite interval mapping for 9 yield and related traits narrowed the yld 2.1 to a region of 62 kb between RM3688 and RM3762 markers. Introgression lines with RM3688 and RM3762 have shown significant increase in yield per plant, grain weight per panicle, number of tillers per plant, panicle length and number of panicles, their grain yield per plant was 17.6 – 20.72% higher than that of ILs with rest of the regions and KMR3, 62 kb region has 10 predicted genes consisting of 4 putative expressed genes including a fertility restorer A homologue like gene, 1 gene encoding 18S pre-ribosomal assembly protein and 5 genes encoding unknown expressed proteins. Significant increase in five important yield and related traits suggests that gene/s underlying this QTL should involve in multiple physiological pathways directly or through epigenetic interactions.