Biocontrol and Growth Promotion Potential of CTXW 7-6-2 against that Causes Tobacco Target Spot Disease.

Fungal diseases form perforated disease spots in tobacco plants, resulting in a decline in tobacco yield and quality. The present study investigated the antagonistic effect of CTXW 7-6-2 against , its ability to promote the growth of tobacco seedlings, and the expression of disease resistance-related genes for efficient and eco-friendly plant disease control. Our results showed that CTXW 7-6-2 had the most vigorous growth after being cultured for 96 h, and its rate of inhibition of growth was 94.02%. The volatile compounds produced by CTXW 7-6-2 inhibited the growth of significantly (by 96.62%). The fungal growthinhibition rate of the CTXW 7-6-2 broth obtained after high-temperature and no-high-temperature sterile fermentation was low, at 50.88% and 54.63%, respectively. The lipopeptides extracted from the CTXW 7-6-2 fermentation broth showed a 74.88% fungal growth inhibition rate at a concentration of 100 mg/l. Scanning and transmission electron microscopy showed some organelle structural abnormalities, collapse, shrinkage, blurring, and dissolution in the mycelia. In addition, CTXW 7-6-2 increased tobacco seedling growth and improved leaf and root weight compared to the control. After CTXW 7-6-2 inoculation, tobacco leaves showed the upregulation of the , , and genes, which are closely related to target spot disease resistance. In conclusion, CTXW 7-6-2 may be an efficient biological control agent in tobacco agriculture and enhance plant growth potential.