Identification and Evaluation of Antiviral Components in Glandular Trichome Secretions of Sun/Air-cured Tobacco

In order to elucidate the control effect of glandular trichome secretions from sun/air-cured tobacco on plant viral diseases and to identify superior active components, this study assessed the anti-TMV activity of ethanol extracts from glandular trichomes of 28 sun/air-cured tobacco germplasm resources using a sap rubbing-inoculation method. In addition, the composition and content of diterpenoids and sucrose esters (SEs) in the glandular trichome secretions were determined by ultra-high performance liquid chromatography (UPLC) and gas chromatography-mass spectrometry (GC-MS). Correlation, partial least squares, and clustering analyses were used to investigate the relationship between the content of glandular trichome secretions and the anti-TMV activity. The results showed that: (1) The ethanolic extracts of glandular trichomes from 19 germplasm samples exhibited antiviral activity against TMV, with Q16 (Meitan sun-cured tobacco) showing the best virucidal effect, inhibiting necrotic spots by 68.87%; (2) There was a significant or extremely significant negative correlation between cis-abienol and α-cembratriene-diol, β-cembratriene-diol, SEI, and SEII. Conversely, cis-abienol showed a significant or extremely significant positive correlation with SEIII, SEIV, and SEV. More importantly, cis-abienol, SEIII, and SEIV exhibited a highly significant positive correlation with the inhibition rate of necrotic spots. (3) Cis-abienol, SEIII, and SEIV were identified as the major active components against TMV in the glandular trichome secretions of sun/air-cured tobacco. Additionally, the validation experiments showed that cis-abienol (200 μg/mL) and SEs (300 μg/mL) exhibited the most antiviral activities, with necrosis inhibition rate of 44.32% and 53.19% respectively. These rates were significantly higer than those achieved by a plant-derived pesticide (0.5% amino-oligosaccharides). The research results provide a material foundation and technical support for the efficient utilization and the development of plant-derived antiviral active components.