Systematic induced resistance in Solanum lycopersicum (L.) against vascular wilt pathogen (Fusarium oxysporum f. sp. lycopersici) by Citrullus colocynthis and Trichoderma viride

Abstract

The antifungal effects ofCitrullus colocynthisextract (Hexane, chloroform, methanol, and water) were testedin vitroonFusarium oxysporumf. sp.lycopersici(Sacc.) W. C. Snyder & H. N. Hans (FOL), the causal agent of Fusarium wilt. Of these, methanol and water extract at 10% showed the highest inhibition of mycelial growth ofFOLby 12.32 and 23.61 mm respectively. The antifungal compounds were identified through Fourier transform infrared (FT-IR) spectroscopy and gas chromatography-mass spectroscopy (GC-MS). The methanol extract was compatible with the biocontrol agentTrichoderma viride. The antagonistic fungi were mass-cultured under laboratory conditions using sorghum seeds. BothT.virideandC.colocynthismethanol extract was also tested alone and together againstFOLunder bothin vitroandin vivoconditions. The combination ofT.virideandC.colocynthisshowed the highest percentage of antifungal activity (82.92%) againstFOLunderin vitroconditions. This study revealed that induced systemic resistance (ISR) in enhancing the disease resistance in tomato plants against Fusarium wilt disease. The combined treatment ofT.virideandC.colocynthissignificantly reduced the disease incidence and index by 21.92 and 27.02% in greenhouse conditions, respectively. Further, the induction of defense enzymes, such as peroxidase (PO), polyphenol oxidase (PPO), β-1,3-glucanase, and chitinase were studied. The accumulation of defense enzyme was greater in plants treated with a combination ofT.virideandC.colocynthiscompared to the control. Reduction of wilt disease in tomato plants due to the involvement of defense-related enzymes is presumed through this experiment.