PtrWRKY75 promotes SA-induced stomatal closure by ROS
production
Recent evidence indicates that SA induces accumulation of ROS and
influences stomatal closure in Arabidopsis (Borsani et
al. , 2001; Ullah et al. , 2018). To explore the function ofPtrWRKY75 in Populus , we measured ROS levels in the OE
lines and WT plants. The OE lines and WT were treated with 0 or 0.5 mM
SA for 0, 0.5, 1, 2, or 3 h, then their leaves were stained with
3,3′-diaminobenzidine (DAB). Hydrogen peroxide
(H2O2) was visualized as a deep brown
product resulting from the reaction of DAB with
H2O2. The leaves of the OE lines were
stained a deeper brown color than that of WT leaves under all conditions
(Figure 2A). Thus, exogenous SA treatment increased the ROS content in
the leaf to higher levels in the OE lines than in WT.
To investigate whether PtrWRKY75 promotes SA-induced stomatal
closure in the OE lines and WT, leaf stomatal movement was observed
under a scanning electron microscope. After treatment with exogenous SA
for 1 h and 2 h, the stomata closed more rapidly in OE lines than in WT
(Figure 2B). The stomatal aperture was much smaller in OE lines than in
WT under exogenous SA treatment (Figure 2C). These results suggested
that PtrWRKY75 promotes SA-induced stomatal closure via ROS
production.