Mutation Scanning in Wheat by Exon Capture and Next-Generation Sequencing.

Area of Science:

• Plant genomics
• Molecular genetics
• Bioinformatics

Background:

• Targeted Induced Local Lesions in Genomes (TILLING) is crucial for identifying genetic variations to understand gene function and develop improved crop alleles.
• Current TILLING methods in wheat, primarily PCR-based, offer limited throughput for large-scale genomic studies.

Purpose of the Study:

• To evaluate the feasibility of next-generation sequencing via exon capture for TILLING in polyploid wheat.
• To assess the efficiency and accuracy of exon capture for detecting mutations in wheat homoeologous genes.

Main Methods:

• Pilot-scale exon capture sequencing targeting ~2 Mbp of wheat coding sequences in three mutagenized lines.
• Mapping sequencing reads to the IWGSC wheat Chromosome Survey Sequences using various algorithms.
• Validation of single nucleotide polymorphisms (SNPs) using competitive PCR assays.

Main Results:

• Detected at least 464 high-confidence SNPs across three mutagenized lines, including known mutations in TaGA20ox1 genes.
• Estimated a mutation rate of ~35 SNPs per Mb, comparable to PCR-based TILLING.
• Identified challenges in mutation calling accuracy due to incomplete homoeologue coverage in the reference genome.

Conclusions:

• Exon capture sequencing is a viable method for mutation detection in polyploid wheat TILLING.
• Improved genomic reference sequences with comprehensive homoeologue coverage are essential for accurate variant identification.
• This approach holds promise for advancing wheat breeding and functional genomics research.