Nematicidal Evaluation and Active Compounds Isolation of Aspergillus japonicus ZW1 against Root-Knot Nematodes Meloidogyne incognita

Abstract

The root-knot nematode is one of the most damaging plant-parasitic nematodes worldwide, and the ecofriendly alternative approach of biological control has been used to suppress nematode populations. Here the nematicidal activity of Aspergillus japonicus ZW1 fermentation filtrate against Meloidogyne incognita was evaluated in vitro and in greenhouse, and the effects of A. japonicus ZW1 fermentation filtrate on seed germination and the active compound of A. japonicus ZW1 fermentation filtrate were determined. The 2-week fermentation filtrate (2-WF) of A. japonicus ZW1 exhibited markedly inhibitory effects on egg hatching, and 5% 2-WF showed potential nematicidal activities on second-stage juveniles (J2s); the mortality of J2s was 100% after 24 h exposure. The internal contents of nematodes were degraded and remarkable protruded wrinkles were present on the body surface of J2s. The nematicidal activity of the fermentation was stable after boiling and was not affected by storage time. A germination assay revealed that 2-WF did not have a negative effect on the viability and germination of corn, wheat, rice, cowpeas, cucumbers, soybeans, or tomato seeds. The pot-grown study confirmed that a 20% fermentation broth solution significantly reduced root galls and egg numbers on tomatoes, and decreased galls and eggs by 47.3% and 51.8% respectively, over Czapek medium and water controls. The active compound from the A. japonicus ZW1 fermentation filtrate was isolated and identified as 1,5-Dimethyl Citrate hydrochloride ester on the basis of nuclear magnetic resonance (NMR) and LC-MS (liquid chromatograph-mass spectrometer) techniques. Thus, fermentation of A. japonicus ZW1 could be considered a potential new biological nematicide for the control of M. incognita.

Novel ectophytic nematode antagonistic fungi and its potential application for nematode biocontrol

“…Our results indicated that T. cystophila GX1 could predate cyst, and its fermentation ltrate and spore suspension inhibited eggs hatching and toxic to nematodes in vitro, and dense vacuolar in body of eggs and J2s. Similar phenomenon observed by He et al (2020), where 1,5-Dimethyl Citrate hydrochloride ester from the fermentation ltrate of Aspergillus japonicus ZW-1 cause wrinkling on the surface of J2s, and dense vacuolar areas in the cytoplasm. Previous studies have shown that Talaromyces has unique and speci c extrolites such as duclauxins, glauconic acids, mitorubrins, monascins, purpactins, rubratoxin, vermicellins etc.…”

“…The isolated cysts were immersed in 0.5% NaOCl for 3 min surface disinfection and then gently washed fully with sterilized distilled water to remove the NaOCl, and then crushed with a ground-glass homogenizer to release the eggs from the cysts. Eggs were put in a 30 µm aperture hatching sieve and nested in petri dish (6 cm diameter) containing 3 ml distilled water (He et al 2020). Fresh J2s were collected on the day of the experiment for subsequent experiments.…”

“…He et al 2020). Additionally, all treatments were done in quadruplicate, and experiments were performed in triplicate.…”

Natural nematicidal metabolites and advances in their biocontrol capacity on plant parasitic nematodes

“…They displayed nematicidal activity against D. destructor and B. xylophilus. 95 2.6 Simple organic acid 1,5-Dimethyl citrate hydrochloride ester 342 was obtained from Aspergillus japonicus ZW1; it allowed 91.7 ± 0.5% mortality of M. incognita when exposed to 1250 mg mL −1 of the compound at 48 h. 136 Kojic acid 343 is a signicant nematicidal metabolite that was isolated from Aspergillus oryzae. It showed dosedependent mortality and inhibited the egg hatching of M. incognita.…”

Bacteria from the Sonoran Desert with nematicidal potential against phytopathogenic nematodes

“…In addition, there is evidence of their negative impact on the environment, for example, the contamination of groundwater, disturbance of soil fertility, and the accumulation of chemical residues within the trophic levels of soil ecosystems (Engelbrecht et al, 2018). As ecofriendly alternatives, the use of microorganisms and/or their metabolites as biological control agents has attracted scienti c interest due to their minimal environmental side effects (He et al 2020; Engelbrecht et al, 2018).…”