Fig. 1: Massive increase in crossovers through combination of zyp1 mutation and HEI10 overexpression.

A MLH1 foci in Col wild type and zyp1 HEI10^{oe homo} meiocytes. Following immunolocalization, REC8 (Purple) and HEI10 (Supplementary Fig. 1) were imaged with STED while MLH1 (green) was imaged with confocal microscopy. The maximum intensity projection is shown. Scale bar = 1 µm. B Corresponding MLH1-HEI10 foci quantification, in female and male, inbred Col and hybrid Col/Ler. The HEI10 transgene originates from the C2 line and is either homozygous (HEI10^{oe het}) or heterozygous (HEI10^{oe homo}). Each dot is an individual cell,; circles and triangles are females and males, respectively. the mean is indicated by a bar and a number on the top; The number of analyzed cells are indicted into brackets. P values are from one-way ANOVA followed by Fisher’s LSD test. C Experimental design for construction of female and male hybrid populations for sequencing. Created with BioRender.com. D The number of COs per chromatid set transmitted by female and male gametes of wild type, HEI10^oe, zyp1, and zyp1 HEI10^oe. Each point is a BC1/gamete, circles and triangles are females and males, respectively. The means are indicated by horizontal dashed lines and numbers on the top. P values are from one-way ANOVA followed by Fisher’s LSD test. The population size is shown in parentheses. E Correlation analysis between mean number of COs per transmitted chromatid and chromosome size (Mb). Error bars are the 90% confidence intervals of the mean. Pearson’s correlation coefficients are shown in parentheses. The sample sizes, n, are identical to panel D. F Genotypes are shown for representative transmitted chromatid sets in wild type and mutants, and for extreme cases in zyp1 HEI10^oe. Centromere positions are indicated by white points. Source data are provided as a Source Data file.