Thousands of trait-specific KASP markers designed for diverse breeding applications in rice (Oryza sativa)

Abstract

This study aimed to broaden applicability of KASP for Oryza sativa across diverse genotypes through incorporation of ambiguous (degenerate) bases into their primer designs and to validate 4000 of them for genotyping applications. A bioinformatics pipeline was used to compare 129 rice genomes from 89 countries with the indica reference genome R498 and generate ∼1.6 million KASP designs for the more common variants between R498 and the other genomes. Of the designs, 98,238 were for predicted functional markers. Up to five KASP each for 1024 breeder-selected loci were assayed in a panel of 178 diverse rice varieties, generating 3366 validated KASP. The 84% success rate was within the normal range for KASP demonstrating that the ambiguous bases do not compromise efficacy. The 3366-trait-specific marker panel was applied for population structure analysis in the diversity panel and resolved them into four expected groups. Target variations in thirteen of the genome sequences used for designs were compared with the corresponding KASP genotypes of other accessions of the same thirteen varieties in the diversity panel. There was agreement across 12 varieties for 79% of markers. Ten varieties had high agreement (>88%) but a variety selected from a landrace had only 46.5% agreement. Breeders can now search for the validated KASP and >1 million so-far untested designs across three alternative reference genomes (including Niponbare MSU7), search for designs proximal to previously published SSR markers and retrieve the target variations in 129 rice genomes plus their genomic locations with +/-25 bp flanking sequences.