Micro-haplotyping in potato using massively parallel amplicon sequencing

Background: Haplotyping in polyploids is a very relevant but challenging task. Most methods based on short-read technologies require haplotype assembly, which is error-prone and computationally intensive. However, most (auto)polyploids have high SNP densities. Therefore, haplotyping could already be done in regions of a size that can be entirely covered by reads generated by current short-read sequencing techniques. Here, we used a method that enables massively parallel amplicon sequencing in order to generate such micro-haplotypes in autotetraploid potato and autohexaploid chrysanthemum.Results: For potato, we generated 79 million reads to sequence 412 regions in 96 samples. The average region size was 154 base-pairs. On average, we found 2.4 haplotypes per locus per individual. For chrysanthemum, we generated a similar amount of reads to sequence 940 regions in 92 samples. The average region size here was 171 base-pairs. On average, 2.7 haplotypes per locus per individual were found. Concordance with dosage data based on SNP-arrays was up to 96.8% in potato and 93.2% in chrysanthemum.Conclusions: Interpretation of genotyping data generated with next-generation sequencing can be challenging in polyploids, because estimation of allele dosages is often a requisite. Taking advantage of high SNP densities in many autopolyploids we show that massively parallel amplicon sequencing can generate high-quality data with high information content. This has a broad range of applications, including linkage mapping, diversity studies, and genomic selection.