Figure 3 PtrWRKY75 promotes salicylic acid (SA) biosynthesis by activating PtrPAL1 transcription.
(A) Free SA levels in mature leaves from 35-day-old plants under non-stress and dehydration conditions. Data are means ± SE (n = 3). Data were analyzed using one-way analysis of variance followed by Duncan’s multiple range test. Asterisks denote significant differences: *P ≤ 0.05;**P < 0.01.
(B) Quantitative real-time PCR (qRT-PCR) analysis of transcript levels of PtrSID2 under non-stress and dehydration conditions. Data are means ± SE (n = 6). Data were analyzed using one-way analysis of variance followed by Duncan’s multiple range test.
(C) qRT-PCR analysis of PtrPAL1 transcript levels under non-stress and dehydration conditions. Data are means ± SE (n = 6). Data were analyzed using one-way analysis of variance followed by Duncan’s multiple range test. Asterisks denote significant differences: *P ≤ 0.05; **P < 0.01.
(D) Locations of putative WRKY75 binding sites in PAL1 promoter.
(E) EMSA analysis of binding of recombinant WRKY75 protein toPAL1 promoter. Hot probe is biotin-labeled, and hot mProbe contains a single nucleic acid mutation from TGAC to TAAC.
(F) Promoter activity analysis of SA biosynthetic gene PtrPAL1using PtrWRKY75 as effector under non-stress and dehydration conditions. Promoter of PAL1 was isolated from P. trichocarpa genome. Data are means ± SE (n = 6). Data were analyzed using one-way analysis of variance followed by Duncan’s multiple range test. Asterisks denote significant differences: **P < 0.01.