Resistance induction in cucumber and direct antifungal activity of zirconium oxide nanoparticles against Rhizoctonia solani.

Zirconium oxide nanoparticles (ZrONPs) were synthesized and evaluated for their ability to induce root rot resistance in cucumber and direct antifungal activity against Rhizoctonia solani. Resistance induction was investigated using real-time polymerase chain reaction (RT-PCR) and the effect of ZrONPs on the growth of cucumber plants was investigated. The results showed that ZrONPs at a concentration level of 100 μg/L significantly inhibited the growth of Rhizoctonia solani (86.6%) relative to untreated control under laboratory conditions. Cucumber plants treated with ZrONPs showed reduction in the severity of root rot disease under greenhouse (34-46%) and field conditions (52-56%) compared with non-treated control plants. Cucumber plants treated with ZrONPs expressed regulatory and defense genes involved in the salicylic acid (SA) and jasmonic acid (JA)/ethylene (ET) signaling pathways with 7-8 folds higher than the control. Treatment of cucumber with ZrONPs and carboxin + thiram significantly improved cucumber growth and yield characters. Therefore, using ZrONPs could be a new strategy to control this pathogen and considered the first report.