An enrichment method for mapping ambiguous reads to the reference genome for NGS analysis

Area of Science:

• Genomics
• Bioinformatics
• Computational Biology

Background:

• Accurate read mapping is vital for next-generation sequencing (NGS) analyses.
• Large plant genomes present challenges due to ambiguous read alignments.
• Current random read assignment methods may impact downstream genomic analyses.

Purpose of the Study:

• To evaluate alternative methods for mapping ambiguous reads in large plant genomes.
• To compare the enrichment and probability methods against the default random assignment.
• To assess the impact of read mapping strategies on single nucleotide polymorphism (SNP) discovery and quality.

Main Methods:

• Developed and tested the enrichment method: assigning ambiguous reads to the highest-producing genomic location.
• Developed and tested the probability method: assigning ambiguous reads probabilistically based on location output.
• Systematically compared proposed methods with the traditional random assignment method.

Main Results:

• The enrichment method significantly outperformed both random and probability methods in SNP discovery.
• The enrichment method yielded a higher number of SNP markers.
• SNP markers identified using the enrichment method demonstrated superior quality, validated through genome-wide association studies (GWAS), population structure, and genomic prediction.

Conclusions:

• The enrichment method offers a superior strategy for mapping ambiguous reads in large plant genomes.
• Improved SNP discovery and quality using the enrichment method enhance downstream genomic applications.
• This approach provides more reliable genetic markers for plant breeding and research.