(A) RMG1 mRNA levels in Col-0 and the two rmg1 mutant alleles, namely rmg1-1 and rmg1-2, were monitored by RT-qPCR at 6 hr after syringe-infiltration of mock (water) or 1 μM of flg22 peptide. (B) RMG1 positively regulates vascular resistance towards Pto DC3000. Secondary veins of 5-week-old Col-0, ros1-3, rmg1-1, and rmg1-2 plants were inoculated with Pto DC3000-GFP at 5 × 106 cfu ml−1 using the toothpick inoculation method. Inoculation was done on six secondary veins per leaf and two sites of inoculation per vein. At least 10 leaves per condition were quantified. The number of Pto DC3000-GFP spreading events from the wound inoculation sites was quantified after 3 days under UV light using a macrozoom. When the Pto DC3000-GFP propagated away from any of the 12 inoculation sites, it was indexed as propagation with a possibility of maximum 18 propagations per leaf. The values from three independent experiments were considered for the comparative analysis. Statistical significance was assessed using a one-way ANOVA test. (C) RMG1 positively regulates apoplastic resistance towards Pto DC3000. Five-week-old Col-0, ros1-3, rmg1-1, and rmg1-2 plants were dip-inoculated with Pto DC3000-GFP at 5 × 107 cfu ml−1. Bacterial titres were monitored at 3 days post-infection (dpi). Each data point represents bacterial titre at four leaf discs extracted from two different leaves. At least three leaves out of four plants per line per experiment and from three independent experiments were considered for the comparative analysis. Statistical significance was assessed using a one-way ANOVA test. (D) Flg22-triggered induction of RMG1 is compromised in ros1-3-elicited mutant and correlates with an increased DNA methylation and siRNA levels at the remnant RC/Helitron TE AtREP11, and particularly at its 3’ boundary. IGV snapshots showing mRNA levels (mRNA-seq) after syringe-infiltration of mock (water) or 1 μM of flg22 peptide for Col-0 and ros1-3, and cytosine DNA methylation levels (Bs-Seq) and siRNA levels (sRNA-seq) in 5-week-old untreated rosette leaves of Col-0 and ros1-3, at the RMG1 locus. The hyperDMR is highlighted by the dotted box. (E) Levels of different siRNA species at the 3’ boundary of AtREP11. IGV snapshots representing the levels of methylation (BS-seq), total siRNA species (siRNA-seq), and different size of siRNA species (21nt, 22nt, 23nt, and 24nt siRNAs) in 5-week-old rosette leaves of Col-0, ros1-3, and ros1dcl23. (F) The flg22-triggered induction of RMG1 is fully restored in ros1dcl23-elicited triple mutants. RT-qPCR analysis depicting RMG1 and FRK1 mRNA levels in Col-0, ros1-3, dcl23, and ros1dcl23 5-week-old rosette leaves treated with either mock (water) or 1 μM of flg22 for 6 hr. The mRNA levels are relative to the level of UBQ transcripts. Statistical significance of flg22 treatment on expression was assessed using a two-way ANOVA test and a Sidak’s multiple comparisons test. Asterisks indicate statistical significance (*: p<0.05, **: p<0.01, ***: p<0.001, ns: not significant).