Arbutin- and benzotiadiazole-mediated cucumber response to Pseudomonas syringae pv. lachrymans infection in carbohydrate metabolism

• Arbutin limited angular leaf spot disease symptom development in cucumber
• Compared with BTH, arbutin improved plant fitness and leaf growth
• Discussed is the sugar metabolism-related potential mechanism of arbutin action

The effect of exogenous arbutin (ARB) or benzotiadiazole (BTH) on carbohydrate metabolism in cucumber infected with Pseudomonas syringae pv. lachrymans was studied. Glucose, sucrose, chlorophyll and carotenoid levels, acid and alkaline invertase and lactate dehydrogenase activities at the local (3rd, inoculated leaf) and systemic (5th, non-inoculated leaf) levels were determined. ARB limited disease symptom development to an extent similar to BTH. It was shown that both compounds effectively protected cucumber plants against this hemibiotrophic pathogen, however, the mechanisms of their activity are different. In the ARB-treated plants following the infection younger leaves were in better condition than BTH-treated ones due to more effective carbohydrate metabolism. Moreover, as opposed to BTH, ARB was not cytotoxic for plant tissues.