No abstract

Certain natural products extracted from different parts of medicinal and aromatic plants were examined for their antifungal activity against three plant pathogenic fungi, Fusarium oxysporum, Rhizoctonia solani, and Alternaria solani, and insecticidal activity against mosquito larvae (Culex pipiens). Acetone extract of Tectona grandis showed the highest antifungal activity against R. solani and A. solani with EC50 values of 118 and 294 μg/mL, respectively. The highest larvicidal activity was displayed by the essential oils of Ocimum basilicum and Eucalyptus gomphocephala with LC50 value of 22, and 30 mg/L, respectively. By gas chromatography–mass spectrometry (GC/MS) analysis 3-allylguaiacol (65.8%) and eugenol acetate (46.6%) were the main compounds in Syzygium aromaticum methanolic extract and essential oil, respectively. The main compound in T. grandis acetone extract was cyclohexylpentyl oxalate (8.7%); its water extract contained (E)-4,4-dimethyl-2-pentene (51.1%); E. gomphocephala branch oil contained p-cymene (28.8%); Euphorbia paralias leaf extract contained 1βH-romneine (26.3%); the seed extract contained α-linolenic acid, TMS (15.2%); Punica granatum extract contained furfural (32.1%); and O. basilicum essential oil contained estragole (65.9%). Thus, extracts from the tested plants can be used as natural biofungicides to manage diseases caused by F. oxysporum, R. solani, and A. solani. Additionally, these extracts show potential larvicide activities against mosquito larvae.

Fusarium wilt of tomato (FW) caused by Fusarium oxysporum f. sp. lycopersici (FOL) is a major challenge for tomato production worldwide. For sustainable management of FW, the potential of five strains of Trichoderma asperellum was evaluated under greenhouse conditions. The results indicated that FOL infected plants treated with T. asperellum strains significantly reduced disease incidence and severity compared with FOL-only infected plants. The reduction of wilt disease on plants treated with T. asperellum strains was accompanied by a significant reduction in FOL populations in tomato stems and rhizosphere. Moreover, the application of T. asperellum promoted tomato plant growth irrespective of the presence or absence of FOL. Two strains of T. asperellum (TS-12 and TS-39) that showed the best performance in minimizing disease development and increases in plant growth parameters were selected for elucidating their ability in triggering tomato defense mechanisms. The expression levels of defense-related genes, chitinase (SlChi3), β-1,3-glucanase (SlGluA) and PR-1 (SlPR-1a) were significantly increased in the stems and roots of Trichoderma treated, FOL infected plants, compared with FOL-only infected ones. These results indicate that the application of T. asperellum strains TS-12 and TS-39 can be used as an alternative strategy to manage FW through their antagonistic activities and abilities to induce systemic resistance.