Development and application of indica–japonica SNP assays using the Fluidigm platform for rice genetic analysis and molecular breeding

Molecular markers are efficient and essential genotyping tools for molecular breeding and genetic analysis of rice. We developed two 96-plex indica–japonica single nucleotide polymorphism (SNP) genotyping sets for genetic analysis and molecular breeding in rice using the Fluidigm platform. Informative SNPs between indica and japonica were selected from SNP data of the Rice Diversity database, HapRice world SNP data of the Q-TARO database, and our 40 rice cultivar resequencing dataset. SNPs in set 1 were evenly distributed across all 12 rice chromosomes at a spacing of 4–5 Mb between adjacent SNPs. SNPs in set 2 mapped to the long genetic intervals in set 1 and included 14 functional or linked SNPs in genes previously cloned and associated with agronomic traits. Additionally, we used the SNP sets developed in this study to perform genetic diversity analysis of various cultivated and wild rice accessions, construction and validation of a subspecies diagnostic subset, linkage map construction and quantitative trait locus (QTL) analysis of a japonica × indica F2 population, and background profiling during marker-assisted backcrossing. Furthermore, we identified subspecies-specific SNPs and discuss their distribution and association with agronomic traits and subspecies differentiation. Our results indicate that these subspecies-specific SNPs were present in wild rice prior to domestication. This genotyping system will serve as an efficient and quick tool for genetic analysis and molecular breeding in rice.