Portulaca oleracea (L.) essential oil inhibits Pestalotiopsis neglecta and controls black spot needle blight in Pinus sylvestris var. mongolica (Litv.)

Abstract

Black spot needle blight in Pinus sylvestris var. mongolica is a common disease caused by Pestalotiopsis neglecta which leads to yellowing and withering of needles, eventually leading to the death of the affected trees. The study investigated the antifungal activity and mechanism of Portulaca oleracea essential oil (POEO) against P. neglecta and its efficacy in controlling black spot needle blight in Pinus sylvestris var. mongolica. In this study, we identified the main components of POEO as linalool and limonene. The antifungal assay proved that POEO could inhibit the growth of P. neglecta, 6 μL/mL of POEO inhibited P. neglecta by 100 % with an EC50 value of 1.16 μL/mL, and the results of scanning electron microscopy confirmed that POEO inhibited the growth of the P. neglecta mycelium. In addition, POEO treatment induced oxidative stress and exacerbated membrane lipid peroxidation of P. neglecta, which ultimately caused serious damage to P. neglecta cell membranes and cell contents leakage. POEO also reduced the activity and virulence of polygalacturonase (PG), endo-1,4-β-D-glucose hydratase (EG), and pectate lyase (PL) secreted by P. neglecta, thereby controlling black-spotted needle blight of Pinus sylvestris var. mongolica, which was able to control black spot needle blight in Pinus sylvestris var. mongolica. In summary, our results revealed the antifungal mechanism of POEO on P. neglecta and provided potential options for controlling black spot needle blight in Pinus sylvestris var. mongolica and other plant diseases.