Wood vinegar alleviates photosynthetic inhibition and oxidative damage caused by Pseudomonas syringae pv. tabaci (Pst) infection in tobacco leaves

ABSTRACT We used chlorophyll fluorescence technology and biochemical methods to analyze the effects of wood vinegar (WV) on the photosynthetic mechanism and reactive oxygen species metabolism of tobacco (Nicotiana tabacum L.) leaves infected by Pseudomonas syringae pv. tabaci (Pst). The results showed that Pst infection reduced the chlorophyll content and the activities of PSII and PSI, which inhibited the normal photosynthesis of tobacco leaves. However, pretreatment with WV alleviated the degradation of chlorophyll. Treatment with WV alleviated the downregulation of core gene expression in PSII and PSI and improved the photosynthetic electron transfer in Pst-infected leaves. The levels of expression of PetE, ATPa and ATPc in the Pst-infected leaves were significantly upregulated when pretreated with WV. Pst infection increased the rate of production of superoxide anions and the contents of hydrogen peroxide. WV pretreatment could eliminate the oxidative damage of Pst-infected leaves by enhancing the activities of peroxidase (POD) and glutathione peroxidase (GPx) and upregulating the levels of expression of the POD2 and GPX2 genes. In conclusion, pretreatment with WV can alleviate the photosynthetic inhibition and oxidative damage of tobacco leaves caused by Pst infection.