Two Nematicidal Compounds from Lysinimonas M4 against the Pine Wood Nematode, Bursaphelenchus xylophilus

Abstract

A rich source of bioactive secondary metabolites from microorgannisms are widely used to control plant diseases in an eco-friendly way. To explore ideal candidates for prevention of pine wilt disease (PWD), a bacterial strain from rhizosphere of Pinus thunbergii, Lysinimonas M4, with nematicidal activity against pine wood nematode (PWN), Bursaphelenchus xylophilus, was isolated. Two nematicidal compounds were obtained from the culture of Lysinimonas M4 by silica gel chromatography based on bioactivity-guided fractionation and were subsequently identified as 2-coumaranone and cyclo-(Phe-Pro) by nuclear magnetic resonance (NMR) and mass spectrometry (MS). The 2-coumaranone and cyclo-(Phe-Pro) showed significant nematicidal activity against PWN, with LC50 values at 24 h of 0.196 mM and 0.425 mM, respectively. Both compounds had significant inhibitory effects on egg hatching, feeding, and reproduction. The study on nematicidal mechanisms revealed that 2-coumaranone and cyclo-(Phe-Pro) caused the accumulation of reactive oxygen species (ROS) in nematodes, along with a notable decrease in CAT and POS activity and an increase in SOD activity in nematodes, which might contribute to the death of pine wood nematodes. Bioassay tests demonstrated that the two compounds could reduce the incidence of wilting in Japanese black pine seedlings. This research offers a new bacterial strain and two metabolites for biocontrol against PWN.

GC-MS Analysis and Antibacterial Activity of Ethanolic and Water Extracts of Malaysian Heterotrigona itama Propolis Against Selected Human Pathogenic Bacteria

“…Hexamethylcyclotrisiloxane was identified as a major compound in several medicinal plants, such as Glochidion candolleanum, Olea europaea, and Bauhinia acuminata, as well as two moss species, namely Cinclidotus fontinaloides and Palustriella commutate, which exhibited potent antibacterial activity against S. aureus, B. subtilis, E. coli, and P. aeruginosa (Mostafa et al, 2011;Krishna et al, 2015;Yayintas et al, 2017;Balachandar et al, 2022). Another compound, 2-coumaranone, was found to be an effective nematicidal against Bursaphelenchus xylophilus, a pine wood nematode that causes pine wilt disease (Sun et al, 2022). On the other hand, diethyl bis(trimethylsilyl) ester silicic acid has been shown to potentially enhance the antibacterial activity of Mucuna pruriens seeds, even at low concentrations (Kumar & Rajeshkumar, 2017).…”

Nematicidal Coumarins from Cnidium monnieri Fruits and Angelica dahurica Roots and Their Physiological Effect on Pine Wood Nematode (Bursaphelenchus xylophilus)

“…The 30 day-old sterile black pine seedlings were prepared according to the method reported by Sun et al [ 11 ]. A total of 10 μL nematode suspension (15 PWNs/μL) was dripped into pine seedlings using a syringe [ 46 ].…”

“…Among various control tactics for PWD prevention, trunk injection of powerful nematicides against PWN remains one of the most effective, sustainable, and reliable strategies [ 3 , 6 , 7 ]. However, commonly used synthetic nematicides have garnered more and more concerns, regarding drug resistance, resulting from repeated applications, toxicity to non-target organisms, and loss of biodiversity [ 1 , 8 , 9 , 10 , 11 ]. Hence, there is an ever-increasing need to search for safer and eco-friendly nematicides to prevent PWN infection [ 8 , 9 ].…”

Cinnamyl Alcohol Dehydrogenase Gene Regulates Bursaphelenchus xylophilus Reproduction and Development

“…The experiment was repeated three times. [56]. The wilting of pine needles of the Pinus thurnbergii seedlings was observed every day [56].…”