Bulk segregant analysis: “An effective approach for mapping consistent-effect drought grain yield QTLs in rice”

Mapping QTLs for grain yield under drought in rice involves phenotyping and genotyping of large mapping populations. The huge cost incurred in genotyping could be considered as a bottleneck in the process. Whole population genotyping (WPG), selective genotyping (SG), and bulk segregant analysis (BSA) approaches were employed for the identification of major grain-yield QTLs under drought in rice in the past few years. The efficiency of different QTL mapping approaches in identifying major-effect grain-yield QTLs under drought in rice was compared using phenotypic and genotypic data of two recombinant inbred line populations, Basmati334/Swarna and N22/MTU1010. All three genotyping approaches were efficient in identifying consistent-effect QTLs with an additive effect of 10% or more. Comparative analysis revealed that SG and BSA required 63.5% and 92.1% fewer data points, respectively, than WPG in the N22/MTU1010 F3:4 mapping population. The BSA approach successfully detected consistent-effect drought grain-yield QTLs qDTY1.1 and qDTY8.1 detected by WPG and SG. Unlike SG, BSA did not lead to an upward estimation of the additive effect and phenotypic variance. The results clearly demonstrate that BSA is the most efficient and effort saving genotyping approach for identifying major grain yield QTLs under drought.