Abstract:

The study aimed to elucidate the resistance mechanisms of different tobacco varieties against tobacco black shank disease. The identification of resistance to tobacco black shank disease of 24 tobacco varieties (lines) was conducted, and four highly resistant varieties, eight moderately resistant varieties, eight moderately susceptible varieties, and four highly susceptible varieties were identified. Two highly resistant varieties and two highly susceptible varieties were selected to determine the activity of antioxidant enzyme system, salicylic acid content, and expression of disease-related genes after Phytophthora parasitica var. nicotianae infection. The results revealed that the antioxidant enzyme activity in highly resistant varieties was significantly higher than that in highly susceptible varieties after infection with P. nicotianae, suggesting that highly resistant varieties have stronger antioxidative capabilities. Additionally, the synthesis of endogenous salicylic acid in high-resistant varieties was significantly stronger than that in highly susceptible varieties after infection with P. nicotianae, and the expression of disease resistance genes was also significantly higher than that in highly susceptible varieties, indicating that resistant varieties can more efficiently trigger their own defense system to resist the invasion of P. nicotianae. The study offers insights into the mechanisms of tobacco against tobacco black shank disease and provides a theoretical foundation for breeding disease-resistant tobacco varieties.

Key words: flue-cured tobacco, black shank disease, disease resistance, Phytophthora nicotianae, antioxidant enzyme, salicylic acid, gene expression