Susceptibility assessment and induced systemic resistance in cucumber genotypes to Fusarium Wilt

Abstract

This study aimed to investigate the efficacy of the bio-fungus Trichoderma viride and the fungicide Hymexazol in inducing systemic resistance (ISR) against Fusarium wilt caused by Fusarium oxysporum f. sp. cucumerinum (F.o.c) in cucumber (Cucumis sativus L.). Two genotypes were evaluated: a susceptible local cultivar and a partially resistant genotype imported from Monsanto Holland B.V. (Seminis). Plants were treated with the inducers, and the expression levels of key defense-related genes were assessed at 24, 48, and 96 hours post-inoculation (hpi) using quantitative real-time PCR (qRT-PCR). The results revealed that both T. viride and Hymexazol significantly enhanced the expression of Chi2 and PR-1 genes in both genotypes compared to untreated controls. The highest gene expression levels were generally observed at early point, indicating rapid activation of plant defense responses. In contrast, the untreated resistant genotype showed only moderate induction of defense-related genes, while the untreated susceptible genotype exhibited minimal or no significant response, highlighting inherent genetic differences in disease resistance. These findings demonstrate the effectiveness of biological and chemical inducers in activating plant defense mechanisms and enhancing ISR. The study provides important insights into the molecular basis of induced resistance and suggests that integrating bio-fungicides with conventional fungicides can be an effective and sustainable strategy for managing Fusarium wilt in cucumber cultivation.