Dynamic changes and spectrometric quantitative analysis of antioxidant enzyme activity of TYLCV-infected tomato plants

Abstract

To investigate the dynamic changes in superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) activities in Tomato yellow leaf curl virus (TYLCV)-infected tomato leaves is essential for monitoring tomato growth, selecting disease-resistant varieties and disease control. Utilizing hyperspectral technique offers a rapid and non-destructive method to estimate antioxidant enzyme activity in tomato leaves. This study focuses on one a TYLCV-susceptible tomato variety (Hezuo 908) and two TYLCV-resistant varieties (Dingyanfen No. 3 and No. 5) to analyze the changes in photosynthetic characteristics and antioxidant enzyme activity following TYLCV infection. Hyperspectral data were used to quantify the correlation between antioxidant enzyme activity and spectral features under different pretreatments, as well as the relationship between enzyme activity and classical spectral indices. Several optimized indices were developed by iterating on the condition of R, forming a combined index. Considering efficiency and complexity, the support vector machine regression algorithm was employed to evaluate the predictive performance of the models. The results showed a decline in photosynthetic rate and relative chlorophyll content, while stomatal conductance initially decreased and then increased. The activities of the three antioxidant enzymes increased. activities of the three antioxidant enzymes post-TYLCV infection, with POD activity correlating with tomato variety resistance—a potential auxiliary index for antiviral variety identification. Among the models, the CAT prediction model performed the best, with a test set determination coefficient (R²) of 0.82, followed by POD with an R² of 0.67, and SOD R² of 0.43. These findings demonstrate that spectra enable rapid and non-destructive estimation of antioxidant enzyme activity in tomatoes under viral stress. This study provides valuable insights for antiviral variety breeding and the early warning of viral diseases.