ABSTRACT
Naturally occurring chromosomal crossovers (CO) during meiosis are a key driver of genetic diversity. The ability to target CO at specific allelic loci in hybrid plants would provide an advantage to the plant breeding process by facilitating trait introgression, and potentially increasing the rate of genetic gain. We present the first demonstration of targeted CO in hybrid maize utilizing the CRISPR Cas12a system. Our experiments showed that stable and heritable targeted CO can be produced in F1 somatic cells using Cas12a at a significantly higher rate than the natural CO in the same interval. Molecular characterization of the recombinant plants demonstrated that the targeted CO were driven by the non-homologous end joining (NHEJ) or HDR repair pathways, presumably during the mitotic cell cycle. These results are a step towards the use of RNA-guided nuclease technology to simplify the creation of targeted genome combinations in progeny and accelerate breeding.
Subject(s)
CRISPR-Cas Systems , Chromosomes, Plant , Crossing Over, Genetic , Gene Editing/methods , Hybridization, Genetic , Zea mays/genetics , DNA End-Joining RepairABSTRACT
Genetic male sterility (GMS) in cotton mediated by two homozygous recessive genes, ms5ms5 and ms6ms6, is expressed as non-dehiscent anthers and unviable pollen grains. Sequence analysis on ms5 and ms6 loci in Gossypium hirsutum was conducted to reveal genomic variation at these two loci between GMS and wild-type G. hirsutum inbred lines, and sequence polymorphism linked to ms5 on A12 and ms6 on D12 was revealed. A haplotype marker set that consisted of four SNPs targeting both ms5 and ms6 gene regions was developed and validated for association with GMS in cotton. Predictability of GMS phenotype by this haplotype SNP set was over 99 %. GMS haplotype marker set can serve as a high-throughput molecular breeding tool to select GMS individuals and improve hybrid production efficiency.
