Screening eight tomato varieties for resistance to Fusarium wilt disease

Fusarium wilt caused by soil-borne fungus Fusarium oxysporum f. sp. lycopersici (Fol) is one of the most important diseases of tomatoes in the world. Identification and cultivation of resistant varieties is an environmentally friendly method of disease management that leads to the production of a chemical-free and clean yield. This research was conducted to evaluate the reactions of eight tomato varieties to the disease and their correlation with peroxidase enzyme.

Wilted tomato plants were sampled in the greenhouses of southwestern Iran and after isolation and purification and studying the morphological characteristics, two Fol  isolates were identified. The reactions of eight varieties vs. Kingston, Dafnis, Super chef, Karnak, CHpooya, Earlypooya, Superpooya, and CH to these two isolates were investigated in a factorial experiment with a completely randomized statistical design with four replications for each treatment under greenhouse conditions. The disease severity index and the vegetative and reproductive indices of the plant were determined. The level of peroxidase enzyme in the leaves of plants of each treatment was measured by spectrophotometric method at 470 nm wavelength and its correlation coefficient was determined with the disease severity index.

Analysis of the variance of these experimental data revealed a significant difference between Fol isolates in pathogenicity and interaction between Fol isolates and varieties. Fol2 isolate was more aggressive than Fol1 and CH was moderately susceptible, and  Earlypooya, Karnak, Superpooya, Dafnis, CHpooya, were moderately resistant, while Kingston and Super chef  were completely resistant to this hyper-virulent isolate of  the pathogen and disease. The peroxidase level had negatively correlated with the disease severity index.

Among these varieties, Kingstone and Super chef are resistant to the disease. Peroxidase levels can be used as a resistance marker to assess how different tomato varieties react to the disease.