Fig. 1

Overview of the Col3-4/20 (♂) × Ler-0 (♀) crossing scheme and possible outcomes of meiotic recombination events and subsequent chromosome segregation. Meiotic reporter line Col3-4/20 (♂) harboring RFP and GFP reporter constructs at the top of the long arm of chromosome 3 (separated by a genetic distance of 16 cM) is crossed with the accession Ler-0 (♀). The resulting F₁ hybrids are selfed and their F₂ seeds are collected. Overall crossover frequencies are calculated from RFP and GFP fluorescence images using the formula for crossover frequency described previously [16]. Crossover events referred to as ‘visible crossover events’ can be observed directly as the F₂ seeds displaying either only RFP or only GFP signal. Crossover events referred to as ‘extrapolated crossover events’ are not directly visible based on the fluorescence images only. The frequency of these events is extrapolated from the fluorescence images based on theoretical allele frequencies as described previously [16]. For the sake of clarity of the figure the chromosomes are presented in the colors of the original parent throughout the crossing scheme (black for Col3-4/20 and blue for Ler-0)