Linkage Mapping of Quantitative Trait Loci for Traits Promoting Aerobic Adaptation on Chromosome 8 in Indica Rice (<i>Oryza sativa</i> L.)

Abstract

Identification of major effect QTLs for traits promoting aerobic adaptation using molecular markers can greatly enhance the efficacy of breeding programs to develop high yielding, direct seeded, water efficient rice varieties. The Filial (F 2 ) population derived from HKR47 high-yielding low-land indica rice variety, and MAS26, aerobic adapted rice variety, was developed and analyzed for the identification of larger and consistent effect QTLs for yield, yield attributing and root traits under aerobic cultivation conditions. The population displayed large variation for all the physio-morphological traits including grain yield per plant and root traits. Phenotypic correlation analysis revealed that grain yield per plant showed positive correlation with root length (r 2 =0.279), fresh root weight (r 2 =0.232) and dry root weight (r=0.269). A total of 803 SSR markers, distributed on 12 rice chromosomes, were analyzed for parental polymorphism survey; of these 125 (about 16%) displayed polymorphism. NTSYS-pc UPGMA tree cluster analysis and two-dimensional PCA scaling showed scattering of the F 2 population between the two distinct parental genotypes; the population was inclined towards MAS26. Composite interval mapping (CIM) analysis revealed a total of six QTLs (qTN 8.1 , qTN 8.2 , qTN 8.3 , qTGW 8.1 , qYPP 8.1 and qRL 8.1 ) on chromosome 8 (within a region of 24.9 cM) which individually explained 13.7%~27.3% of the phenotypic variation. Chromosome 8 also possesses QTL for aroma and kernel elongation demonstrating that it might be difficult to introgress these QTL promoting aerobic adaptation in Basmati rice.