Fig. 4

Sequence alignment, phenotype, and enzyme activity analysis of ERF2 in tomato. A Phylogenetic tree and sequence alignment of ERF2. (a) Phylogenetic tree of ERF2 and other ERF proteins; the phylogenetic tree was constructed via amino acid sequences of the AP2/ERF domain. (b) Alignment of ERF2 with other ERF proteins. ERF2 is composed of an ERF domain. The black and light-gray colors represent identical and conserved amino acids, respectively, and the darker blue colors represent greater percentages of the same amino acid. B Phenotypic and physiological changes after silencing of the ERF2 gene. (a) Silencing of ERF2 decreased disease resistance in tomato plants. The ERF2-silenced plants exhibited disease symptoms with lesions on leaves at 3 dpi, and only a hypersensitive reaction without disease symptoms was observed in TRV2 empty vector plants. (b) Histopathological observation of the accumulation of H₂O₂ and O²⁻. HR, hypersensitive reaction; Le, lesions. C, ROS content (a) and SOD (b), POD (c) and CAT (d) activities in tomato plants after inoculation with S. lycopersici at different time points. The data presented in (C) are the means ± SD from three independent experiments, and different letters above the columns indicate significant differences at the p < 0.05 level