PtrWRKY75 promotes expression of SA-responsive genes
Our results indicated that PtrWRKY7 5 promotes SA biosynthesis by binding to the promoter of PtrPAL1 , subsequently promoting ROS accumulation (Figure 2). Consistent with these results, the expression of PtrPR1 and PtrPR5 , two widely studied SA-responsive genes (Blanco et al. , 2009), was significantly up-regulated in OE plants under dehydration conditions (Figure 7A, B). The results indicated that PtrWRKY75increased SA production by inducing PAL1 transcription, leading to the expression of SA-responsive genes. Thus, our results show that SA-induced ROS production, which leads to stomatal closure (Khokonet al. , 2011; Moriet al. , 2001), enhances drought tolerance in Populus .