AGGRESSIVENESS VARIATIONS AMONG ISOLATES OF FUSARIUM OXYSPOIUM F.SP. LYCOPERSICI BASED ON THE PATHOGENICITY TEST, HOST DEFENSE RESPONSE, AND ISOLATES GENETIC VARIABILITY

El  Shamy, Sawsan; Adss, Ibrahim; Mashaheet, Alsayed M

doi:10.21608/jaesj.2024.318115.1196

AGGRESSIVENESS VARIATIONS AMONG ISOLATES OF FUSARIUM OXYSPOIUM F.SP. LYCOPERSICI BASED ON THE PATHOGENICITY TEST, HOST DEFENSE RESPONSE, AND ISOLATES GENETIC VARIABILITY

Document Type : Full research articles

Authors

¹ Department of plant pathology, Faculty of Agriculture, Damanhur University, El-Beheira, Egypt

² Department of Genetics, Faculty of Agriculture, Damanhur University, El-Beheira, Egypt

10.21608/jaesj.2024.318115.1196

Abstract

Fusarium oxysporum f.sp. lycopersici (FOL) is a soilborne fungus and the causal agent of vascular wilt disease in tomato and results in severe yield losses, challenging tomato production in Egypt and worldwide. As a key step towards controlling this serious disease, this study investigates the aggressiveness of local FOL isolates, and their effects on the plant defense-related enzymes and gene expression, and to estimate the genetic variation among the isolates using RAPD-PCR in relation to their aggressiveness. Nine FOL isolates (Fo1 – Fo9) were isolated from diseased tomato field plants. Tomato (Lycopersicon esculentum Mill) cultivar ‘loggain’ was used to study the pathogenicity of the nine isolates and their effects on two defense-related enzymes: (1) Peroxidase (POD), (2) Polyphenol oxidase (PPO), and the gene expression of the two tested enzymes in the host was quantified using Real-time PCR. Three isolates showed different levels of aggressiveness on the tested cultivar (High: Fo5, followed by Fo3 and Fo1; Moderate: Fo8 and Fo7; Weak: Fo9 and Fo4). The highest enzyme activity and gene expression of PPO and POD were induced by isolates Fo5 and Fo3, followed by Fo1, Fo8, Fo7, and Fo2, because they caused moderate responses, while Isolates Fo9 and Fo4 isolates induced low enzyme activity and gene expression in the host. A high similarity (78.4%) was observed between Fo9 and Fo4 (included in subgroup 2 in the phylogenetic tree), followed by Fo2 and Fo9 with a similarity of 76.9%, while the similarity between Fo7 and Fo8 was 75.5% (included in group 1 in the phylogenetic tree). The lowest similarity (47.3%) was observed between Fo6 and Fo3. These findings showed differences in pathogenicity among the isolates and suggest a connection between the genetic variability and the aggressiveness of the various isolates.

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