FIGURE 1.

Heterosis effects on F1 seed size observed in reciprocal F1 hybrid diploid seeds depends on parent-of-origin effects. (A) F1 hybrid diploid seed size of reciprocal crosses using 2x Ler-0 as pollen donor (represented by blue circles) or as maternal parent (light blue squares). Seed size of selfed isogenic parental lines is also represented (orange triangles) for comparison with their reciprocal F1 offspring. The horizontal red dashed line corresponds to the mean seed size value of the accession 2x Ler-0 (0.1332 mm²). Error bars represent SD. N ≥ 40 seeds/genotype. (B) Natural variation for parent-of-origin effects on seed size across 71 reciprocal F1 hybrid diploids. The red dashed line represents the average difference in mean F1 seed area for the entire set of 71 reciprocal hybrids.