FIGURE 5.

The group III ubiquitin E2 enzymes are essential for PUB13 in attenuating flg22-triggered immune signaling. (A) Callose deposition in group III ubiquitin E2 genes-silenced (TRV-group III) and non-silenced TRV control (TRV) N. benthamiana plants 24 h after infiltration with 40 μM flg22, 40 μM flgII-28, and 2.5 × 10⁸ CFU/ml P. flu55, respectively. Representative microscopic views of callose formation at the infiltrated leaf area are shown. Numbers below each image represent the mean number of callose formation in at least 36 microscopic views (n ≥ 36) from two biological replicates with standard deviation indicated. The experiment was repeated two times with similar results. (B) PUB13-promoted degradation of FLS2 kinase domain (FLS2-KD) in group III ubiquitin E2 genes-silenced (TRV-group III) and non-silenced TRV control (TRV) N. benthamiana protoplasts. HA-fused FLS2-KD was expressed in protoplasts derived from corresponding plants with or without 1 μM flg22 treatment. The accumulation of FLS2-KD was detected by immunoblot. The HA-fused Fni3C89G was used as internal control for equal transfection of the protoplasts. Numbers under the image denote the relative expression level of FLS2-KD in different lanes, with the expression in TRV-group III protoplasts without flg22 treatment set as 1. This experiment was repeated three times with similar result.