Fig. 3. Effects of exogenous SA on the synthesis of MeSA upon pathogen inoculation.

a The expression level of CsSAMT1. b The expression level of CsSAMT2. c Changes in the endogenous MeSA content. Citrus fruits were treated with 2 mM SA or water (control) following harvest, and then 10 μL of P. digitatum spores (5 × 10⁴ spores/mL in suspension) was inoculated, and the fruits (incubated at 25 °C in 90–95% relative humidity) were sampled 0, 8, 24, 48, 72, and 96 h.p.i. Differential expression levels were determined by qRT-PCR. Citrus sinensis actin (XM_006464503) was employed as the housekeeping gene, and the expression level of each CsSAMT gene was calculated as the ratio relative to the control sample at 0 h.p.i. (set as 1). Each value represents the mean ± s.e.m. of three replicates (n = 3)