Kaolin particle film application lowers oxidative damage and DNA methylation on grapevine (Vitis vinifera L.)

The exogenous kaolin application in grapevine has shown a great potential as summer stress mitigation strategy because it positively impacts fruit quality as a result of many molecular and biochemical changes. In the present study we wanted to address the hypothesis that the observed improved antioxidant capacity could also result from a more efficient enzymatic antioxidant system response. For that purpose, the enzymatic activity of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APx), glutathione reductase (GR) and glutathione peroxidase (GPx) were measured in kaolin treated plants, and correlated to some biomarkers of oxidative status, including hydrogen peroxide (H2O2), total thiobarbituric acid reactive substances (TBARS) and proline. Also, to assess if kaolin particle film could mediate epigenetic modifications, the levels of DNA methylation (5-methylcytosine) were assessed in leaf tissues through a stereological analysis. Results showed that the activity of the ascorbate-glutathione cycle key enzymes was boosted in kaolin treated plants, which translated into a less oxidative damage in leaf and berry tissues (lower H2O2 levels and lipid peroxidation). Results also showed that the methylation of DNA, which seems to be stimulated by the harsh environmental conditions, was decreased in leaves from kaolin treated plants.