Figure 2. Transgenerational SAR against Hyaloperonospora arabidopsidis in mutants of Arabidopsis that are impaired in RNA-directed DNA methylation: nrpd2a-1, dcl3–1, ago4–3, clsy1–1 and drd1–6 (experiment A), and kyp-6, drm1drm2 (dd) and drm1drm2kyp (ddk) (experiment B). Induction of transgenerational SAR and challenge inoculation with H. arabidopsidis were performed as described.¹ At 6 d after conidiospore inoculation, stained leaves were microscopically examined and assigned to different classes, as described.¹ Asterisks and P values at the bottom of the graphs indicate statistical differences in class distributions between C₁ and P₁ progenies of each genotype (χ² Test).