Recombination in diverse maize is stable, predictable, and associated with genetic load

Area of Science:

• Genetics
• Evolutionary Biology
• Plant Science

Background:

• Meiotic recombination is a key evolutionary force with significant implications for plant breeding, affecting trait mapping and allele introgression.
• Recombination rates vary widely across the maize genome, influencing selection efficiency and the purging of deleterious mutations.

Purpose of the Study:

• To map recombination breakpoints at high resolution in maize using genotyping-by-sequencing (GBS).
• To investigate the relationship between recombination patterns, genomic features, and genetic load in maize.

Main Methods:

• Utilized genotyping-by-sequencing (GBS) to identify 136,000 recombination breakpoints in maize nested association mapping populations.
• Analyzed the correlation between recombination patterns, gene density, CpG methylation, and DNA methylation/GC content.
• Employed Genomic Evolutionary Rate Profiling (GERP) to assess genetic load in recombination hotspots.

Main Results:

• Recombination patterns are predictable on a broad scale, correlating with gene density and CpG methylation.
• Identified stable recombination hotspots (1 kb–30 kb) with distinct DNA methylation and GC content profiles.
• Found evidence of GC-biased gene conversion in hotspots and reduced genetic load within these regions.

Conclusions:

• Recombination rate variation significantly impacts maize genome evolution and breeding.
• Recombination hotspots are historically stable and associated with lower genetic load, offering potential advantages for plant breeding programs.
• Understanding recombination patterns can enhance strategies for trait mapping and genetic improvement in maize.