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. 2022 Aug 30;190(4):2688–2705. doi: 10.1093/plphys/kiac404

Figure 1.

Figure 1

PtoWRKY40 is negatively regulated at the transcript and protein levels by low-Pi stress. A, The construct containing a GUS reporter gene driven by the promoter of PtoWRKY40 was introduced into poplars. GUS staining showing the tissue expression pattern of PtoWRKY40 in young leaves (YL), root (R), stem (S), and petiole (P). pc: parenchymal cell; ca: cambium; sxf: secondary xylem fibers; phf: phloem fibers; svc: secondary xylem vessel cell; pxf: primary xylem fibers; pi: pitch; xf: xylem fibers; p: phloem; sc: sclerenchyma cell. B, RT–qPCR confirmation of the tissue expression pattern of PtoWRKY40 before and after low-Pi treatment. Including S, mature leaves (MLs), YL, P and R. Error bars indicate SD values from three independent biological replicates. Student’s t test was used to determine significance statistics; *P < 0.05, **P < 0.01. The poplar UBQ gene was used as an internal reference. C, Extract of low-Pi (P−) treated plantlets degrade GST-PtoWRKY40 recombinant protein (Row 1); this can be inhibited by the 26S proteasome inhibitor MG132. The nontreated (P+) extract (Row 3) and the GST protein (Rows 2 and 4) were used as negative controls, respectively. D, Subcellular localization of PtoWRKY40 in poplar mesophyll protoplasts. Empty pBI221 was used as negative control.