A sensitive SYBR Green RT-qPCR method for grapevine virus E and its application for virus detection in different grapevine sample types

To develop a rapid and high-sensitivity method for detection of grapevine virus E(GVE),a SYBR Green based real-time fluorescence quantitative RT-PCR method(RT-qPCR)was established.This method could be used to detect GVE specifically,and the sensitivity was about 100 times greater than conventional RT-PCR.An excellent linear correlation(R=0.997)and a high amplification efficiency(E=97.5%)were obtained from the standard curve of this method.Reproducibility tests revealed that the coefficients of variation in the intra-and inter-assay results were 0.31-1.03%and 0.82--262%,respectively,indicating a good reproduiblity.The RT-qPCR method could be used to detect GVE in a wide range of grapevine sample types.The detection rates of RT-qPCR for nearly all sample types from different positions and seasons were higher than conventional RT-PCR.The detection rates in spring,summer,autumn and winter increased gradually.Samples in autumn and winter were best for detection,and the detection rates of most samples were 80-100%,which were 10 to 40%higher than conventional RT-PCR.In general,old petioles and branches were the best tissues for GVE detection.The detection rates of these samples in each season were all 100%,which were 20 to 40%higher than conventional RT-PCR.The second highest rates were in the old leaf,with detection rates for RT-qPCR of 80-100%in all seasons,which were 20 to 40%higher than conventional RT-PCR.GVE could be difficultly detected in young leaves by conventional RT-PCR,and the detection rates were only 0-50%,while by RT-qPCR the rates could increase to 0--80%.A total of 33 out of 363 samples(belonging to 68 cultivars)from 20 regions in China were detected to be positive by RT-qPCR(9.1%),which was more than twice the rate of the conventional RT-PCR(3.9%).

Elimination of grapevine fleck virus and grapevine rupestris stem pitting-associated virus from Vitis vinifera 87-1 by ribavirin combined with thermotherapy

Vitis vinifera 87-1 plants infected by grapevine fleck virus(GFkV) and grapevine rupestris stem pitting-associated virus(GRSPaV) were used as the plant materials for virus elimination treatment. This study evaluated the effects of ribavirin at different concentrations(15 and 25 μg mL^(–1);R15 and R25, respectively), thermotherapy(37°C;T), and the combination of ribavirin and thermotherapy(R15+T and R25+T) on eliminating viruses from grapevine plants in vitro. Both R15 and R25 had phytotoxic effects and weakened plant growth. Thermotherapy positively affected the growth of grapevine plants. Plant height was significantly greater in T, R15+T, and R25+T than in CK, R15 and R25. The proportion of dead plants after T, R15+T, and R25+T was 51.4, 11.4, and 8.6%, respectively. The survival rates of regenerated plants after all treatments were >68.0%. Ribavirin concentration and treatment time were related to the regeneration of shoot tips and elimination efficiencies of the two viruses. The survival rates of plants after R15+T for 30, 40, and 50 days were 97.3, 90.7, and 74.4%, respectively. The elimination rates of GRSPaV from plants in the three time quantum were 55.6, 84.6, and 93.8%, respectively. The elimination rate of GFkV was 23.9% higher in R25(35/44) than in R15(25/45), and that of GRSPaV was 7.0% higher in R25 than in R15. The combination of thermotherapy and chemotherapy was found to have a positive effect on the eradication of GFkV and GRSPaV, and R25+T for 50 days was able to completely eliminate the two viruses from in vitro grapevines.

High-Sensitivity Detection of Fruit Tree Viruses UsingBacterial Magnetic Particles

Prunus necrotic ring spot virus （PNRSV） and grapevine fanleaf virus （GFLV） were detected by fluoroimmunoassay using bacterial magnetic particles （BMPs）, and a double antibody sandwich enzyme linked immunosorbent assay （DAS-ELISA）. For the fluoroimmunoassay, fluorescein isothiocyanate labeled anti-PNRSV antibody or anti-GFLV antibody was conjugated onto BMPs of Magnetospirillum gryphiswaldense MSR-1. With this method, a very low minimum antigen concentration （1×10^6 dilution of the original sample concentration） could be detected. Using DAS-ELISA, the minimum antigen detection concentration was the original sample concentration. Thus, comparing these two methods, a BMP-based method could increase the sensitivity up to six orders of magnitude （10^6） higher than an ELISA-based method of detection PNRSV and GFLV.