Fig 1.
Treatment effects on DNA methylation Fig 1a: PCA of differentiation in methylation sensitive loci state shows a clear separation of samples from leaves and flowers.
Methylome changes upon the different treatments (control, herbivory, and MeJA) were significant in both leaves and flowers, but much more prominent in leaf tissue than in flower tissue. Centroid positions of the control -, herbivory-, and MeJA group are indicated with LC, LH, and LJ for the leaf samples, and with FC, FH, and FJ respectively for the flower samples. Fig 1b: Number of loci detected with locus-by-locus AMOVA in both tissues and treatments with either a significant methylation gain (change from an unmethylated to an external, internal, or hypermethylated state as well as change from an external or internal to a hypermethylated state) or methylation loss (change from an external or internal to an unmethylated state as well as change from a hypermethylated to an external, internal, or unmethylated state). Results of the two-sided χ2-tests: Leaves Herbivory: χ2 = 5.921, P = 0.015; Leaves MeJA: χ2 = 16.173, P<0.001; Flowers Herbivory: χ2 = 0.071, P = 0.789; Flowers MeJA: χ2 = 5.063, P = 0.024 (α = 0.05).
Table 1.
Epigenetic differentiation between leaf and flower tissue of Brassica rapa R-o-18 plants after herbivory and MeJA treatment.
Fig 2.
Treatment effects on morphology and floral volatiles Boxplots showing the effect of the herbivory and MeJA treatment on morphological traits and the emission of the main VOC classes in B. rapa.
Herbivory led to a decrease in morphological traits (plant height, flower number, diameter, and spacing, and inflorescence volume) and nitrogenous VOC, while MeJA application led to a significant change in the cumulative emission of total aromatic, fatty acid derivatives (FAD), and nitrogenous VOC. Letters (a, b) above boxes indicate different significance groups (α = 0.05).
Table 2.
Phenotypic changes of B. rapa R-o-18 plants after herbivory and MeJA treatment.
Fig 3.
Effect of DNA demethylation on plant morphology, floral volatiles, and pollinator choice Fig 3a: Plots showing treatment × genotype interactions on morphological traits and floral volatiles (VOC).
A comparison of trait divergence between treatment (left points in each line plot) and control group (right points) across all plant genotypes shows pronounced treatment × genotype interactions for all traits (lines connecting both points; e.g. stronger treatment effects in genotype C, and weaker effects in genotype D). Significant treatment effects are indicated in S3 and S4 Tables. Fig 3b: Barplot showing the choice of B. terrestris in the two-choice assays between control and 5-azaC treatment (percentage and total choices) for all plants as well as for individual genotypes. In total, control plants were favoured over 5-azaC-treated plants with 66.4% to 33.6% landings (top bar with significance asterisks, α = 0.05). The preference for control plants was dependent on plant genotype and very pronounced in genotype C (bars below).
Table 3.
Phenotypic changes in different genotypes of rapid-cycling B. rapa plants after 5-azaC treatment.
(post-hoc multiple phenotypic comparisons).