Search

Unlike chemical pesticides, antiviral plants are biodegradable, replenishable and safe. In this study, 14 sesquiterpene compounds from Tithonia diversifolia were tested for their activities against Tobacco mosaic virus (TMV) using the half-leaf method. Tagitinin C (Ses-2) and 1β-methoxydiversifolin-3-0-methyl ether (Ses-5) were found to have in vivo curative activities of 62.86% and 60.27% respectively, at concentrations of 100μg/mL, respectively. In contrast, the in vivo curative inhibition rate of control agent ningnanmycin was 52.48%. Indirect enzyme-linked immunosorbent assay (ID-ELISA) also verified Ses-2 and Ses-5 had higher inhibition activities than the control agent ningnanmycin. Additionally, qRT-PCR showed that both Ses-2 and Ses-5 can partly inhibit the expression of CP and RdRp, two genes that play key roles in TMV infection. When TMV started to systemically spread, Ses-2 inhibited CP expression while Ses-5 inhibited RdRp expression. These results suggest that the two bio-agents have anti-TMV activities and may be used as bio-pesticides to control the plant virus.

Background: Emerging tospoviruses cause significant yield losses and quality reduction in vegetables, ornamentals, and legumes throughout the world. So far, eight tospoviruses were reported in China. Tomato fruits displaying necrotic and concentric ringspot symptoms were found in Guizhou province of southwest China. Finding: ELISA experiments showed that crude saps of the diseased tomato fruit samples reacted with antiserum against Tomato zonate spot virus (TZSV). Electron microscopy detected presence of quasi-spherical, enveloped particles of 80–100 nm in such saps. The putative virus isolate was designated 2009-GZT. Mechanical back-inoculation showed that 2009-GZT could infect systemically some solanaceous crop and non-crop plants including Capiscum annuum, Datura stramonium, Nicotiana benthamiana, N. rustica, N. tabacum and Solanum lycopersicum. The 3012 nt full-length sequence of 2009-GZT S RNA shared 68.2% nt identity with that of Calla lily chlorotic spot virus (CCSV), the highest among all compared viruses. This RNA was predicted to encode a non-structural protein (NSs) (459 aa, 51.7 kDa) and a nucleocapsid protein (N) (278 aa, 30.3 kDa). The N protein shared 85.8% amino acid identity with that of CCSV. The NSs protein shared 82.7% amino acid identity with that of Tomato zonate spot virus(TZSV). Conclusion: Our results indicate that the isolate 2009-GZT is a new species of Tospovirus, which is named Tomato necrotic spot virus (TNSV). This finding suggests that a detailed survey in China is warranted to further understand the occurrence and distribution of tospoviruses.