Tetrad analysis detecting meiotic CO and NCO tracts using genomic sequencing in Arabidopsis. (A) A schematic illustration for generation of meiotic progeny plants (MPPs) to detect meiotic recombination using high-throughput sequencing. (Blue) Col genotype; (red) Ler genotype. (B) An example of detected CO on Chr2. MPP-A has a pure Col genotype, except one red bar, possibly due to sequencing error. MPP-B has equal representation of blue and red bars, carrying the Ler paternal genotype and the Col maternal genotype. Sequence exchange between MPP-C and MPP-D shows a CO event. One red bar in MPP-D to the right was likely due to sequencing error. The CO tract in the middle contains a 3:1 gene conversion, indicating repair of DSB in the Ler chromatid by using the homologous Col chromatid as a template. (C) An example of detected NCO in Chr1 from the first meiosis. Conversion occurred in the chromatid inherited by MPP-C from the Col to Ler genotype, leading to the 3:1 ratio in this region. (Blue horizontal bars) Mapped reads with a Col-specific SNP; (red bars) reads with a Ler-specific SNP; (gray bars) reads without a SNP. Each MPP plant contains one set of chromosomes from a Col/Col mother and another set of chromosomes from a Col/Ler hybrid.
