Endophytic fungi produce various mixtures of carbon-based compounds, which are known as volatile organic compounds (VOCs). Research regarding the use of VOCs as pesticide substitutes has garnered much attention. This review summarizes the recent knowledge about VOCs regarding their origin and chemical properties and emphasizes their antimicrobial potential against a wide variety of agricultural pathogens. Several studies have highlighted the importance of VOCs as antimicrobial agents. Nevertheless, the application of VOCs in biofumigation methods still requires the advanced evaluation of their phytotoxicity.

This study evaluated the antifungal effects of various volatile organic compounds (VOCs) against two common pathogens: Fusarium culmorum and Cochliobolus sativus. Among the various VOCs, methyl propanoate (MP) and methyl prop-2-enoate (MA) exhibited remarkable antifungal effects under different experimental conditions (direct or indirect contact) and at different concentrations (500–1000 μM). In addition, the type of antifungal effect (fungistatic or fungicidal) appeared to be strongly correlated with the VOC concentrations. Additional tests revealed that both molecules increased membrane permeability of pathogenic spores, which resulted in a decreased efflux of K⁺ ions into the intracellular medium.

The antifungal effects of laurel, myrtle and peppermint essential oils and their combinations were investigated in vitro on two strains of Alternaria alternata mycelial growth and in vivo on detached Citrus leaf disease incidence. Myrtle essential oil was rich in α-pinene and 1,8-cineole while peppermint essential oil in menthol and menthone. 1,8-Cineole was the main component of the essential oils from laurel, laurel + myrtle and peppermint + laurel. The combined peppermint and myrtle essential oil was characterized by the predominance of menthol and 1,8-cineole. All tested essential oils, incorporated in potato-dextrose agar, inhibited A. alternata mycelial growth and had a fungistatic effect at concentration 3 mg/mL of medium. A great synergism was detected between peppermint and laurel essential oils against the two strains of A. alternata. The combined laurel and peppermint essential oil reduced mycelial growth rates of inoculated detached leaves at concentration above 1.5 mg/mL.

This study aimed to determine the effect of Volatile Organic Compounds (VOCs) on some pathogens, these VOCs were emitted during interactions of barley with Fusarium culmorum Schltdl and/or Cochliobolus sativus Shoemaker, two common root rot pathogens. Our work shows that two organic esters: methyl propanoate (MP) and methyl prop-2-enoate (MA) significantly reduced the development of fungi in vitro. Additional tests showed that the esters significantly inhibited spore germination of these pathogens. The activity of these VOCs on a wide range of fungal and bacterial pathogens was also tested in vitro and showed inhibitory action. The effect of the VOCs on infected barley seeds also showed plantlets growing without disease symptoms. MA and MP seem to have potential value as alternative plant protection compounds against barley bioagressors.

The peel’s essential oil of the Tunisian Citrus sinensis (L.) Osbeck var ‘Maltaise demi sanguine’ cultivated in six regions and three bioclimatic stages was analyzed by gas chromatography. Essential oil yields were highly affected by the growing region and stage. The highest oil yield was observed at sub-humid stage: 1.41% in Oued-Mliz, 0.95% in Bizerte and 0.84% in Takelsa and the weakest yield percentage of 0.71% was found in Kairouan characterized by an arid superior stage. The main components limonene, linalool, α-terpineol, 4-Terpineol and β-myrcene showed significant variations in dry region. Principal component analysis and hierarchical clustering of composition revealed high effect of the bioclimatic stage, the coastal location and the altitude. Besides this, the results of this investigation provided a preliminary evidence for specific markers to each region that could constitute a useful tool in the quality control and the determination of the botanical origin of the oils.

Sixty-three isolates of Pyrenophora tritici-repentis collected from various wheat areas of the north of Tunisia were characterized and studied for their variability. Under in vitro conditions, morpho-cultural characterization showed the presence of several colors of colonies. An inoculation bioassay was performed identifying the presence of three symptoms type i.e., small brown spots, chlorosis, and necrosis with chlorosis. ANOVA of leaf infected area and lesion length data caused by isolates showed significant difference, and Ascending Hierarchical Clustering discriminated them into two distinct pathogenic profiles. Molecular detection of virulence effector genes demonstrated the presence of ToxA, ToxB, and toxb gene individually or in combination, resulting in five different gene profiles. These results indicate large variability of features. Multiple Correspondence Analysis and Ascending Hierarchical Clustering identified four distinct isolates classes. Both pathogenic profiles of isolates appeared in all the groups. Hence, it was not possible to establish a relationship between variability characters and geographical regions from which the isolates were collected.