The effect and mechanism of Dufulin in controlling tomato yellow leaf curl virus on tomato plants

Background: Tomato yellow leaf curl virus (TYLCV) causes critical production loss in tomato cultivation. The control of TYLCV in tomato is done mainly by using pesticide which is difficult and expensive, making it essential to find an environmentally friendly chemical agent to control TYLCV. Dufulin has been widely used to prevent and control viral diseases in tobacco and rice in recent years. In this study, we investigated the effect and mechanism of Dufulin on TYLCV on tomato plants. Methods: : The control effect of Dufulin on TYLCV was evaluated by field experiments. The expression level of PI II and NPR1 in healthy and TYLCV-infected tomato after treatments were determined by Real-time fluorescent quantitative PCR (qRT-PCR). Handheld chlorophyll meter was applied to compare the content of chlorophyll and nitrogen in healthy and TYLCV-infected tomato after treatments. Results: : It showed that the relative control effect of 20% Dufulin on TYLCV reached above 68% in 2018 to 2020. Jasmonic acid (JA) level was higher on healthy tomato, but lower on TYLCV-infected tomato plants treated with Dufulin compared to control. Salicylic acid (SA) level was higher on healthy and TYLCV-infected tomato plants treated with Dufulin compared to control. Chlorophyll content on healthy and TYLCV-infected tomato plants was higher after treatment with Dufulin compared to control. Nitrogen content on tomato plants showed no significant difference after spraying Dufulin compared to control. Conclusions: : We found the first evidence of control effects TYLCV using Dufulin. It induced plant defense and increased plant chlorophyll content to help plants resist infection which is helpful for future control of TYLCV in tomato.