Figure 3.

Activation of salicylic acid and jasmonic acid defense signaling genes in rust‐infected leaves of Populus nigra trees. Samples were collected from separate trees at each time point. The messenger RNA levels of (a, b) WRKY transcription factors, (c) nonexpresser of pathogenesis‐related gene (NPR1), (d, e) pathogenesis‐related (PR) genes, and (f) jasmonate ZIM‐domain encoding gene (JAZ10a) were measured by quantitative reverse transcription PCR in three technical replicates per sample. Transcript levels of each gene were normalized to Ubiquitin expression. Corresponding hormone data are depicted in Fig. 2. Data were analyzed using a two‐way ANOVA. Data are presented as the mean ± SE (n = 5), with each replicate consisting of a pool of six fully expanded leaf laminae from a single tree (leaf plastochron index 5–10). tr, treatment; t, time post inoculation; ns, nonsignificant; *, P ≤ 0.05; **, P ≤ 0.01; ***, P ≤ 0.001.