HLVd in hop gardens in Czech republic
P. Svoboda1, J. Matousek2, J. Patzak, K. Krofta,
1Hop research institute, Co., Ltd, Kadanska 2525, 438 46
Viroids are the smallest autonomously replicating pathogenic agent yet describe. They are responsible for significant losses of agricultural crops e.g. potato, avocado, coconut palm and hop. In hop plant are present two viroids: hop stunt viroid (HSVd) and hop latent viroid (HLVd) with worldwide distributions. For control presentation of HLVd was used isolation pathogenic RNA from cones with identification by Dot – blot molecular hybridisation with radioactively designated probes and from tissues and leaves by Concert™ Plant RNA reagent (Invitrogen, USA) for RT- PCR. Molecular sampling from hop garden was performed. We controlled in vitro plants in the Gene bank of hop, mother plant in greenhouse, experimental hop garden, hop garden under health control, nursery, young and old hop gardens. No morphological symptoms were observed on infected plants. In our experiments we have found HLVd and infection is practically 100% and spreading in hop garden is very rapid. Results are important for elimination of HLVd and production virus and viroid free planting material of hop in Czech Republic. This work was supported by the National Agency for Agricultural research of the Ministry of Agriculture in projects QD 1181 and QC 1183.
CHARACTERISATION OF THE TRANSMISSION OF BARLEY MILD MOSAIC VIRUS BY VECTOR POLYMYXA GRAMINIS
Khalid Alhudaib, Mike Adams and Kostya Kanyuka
Plant-Pathogen Interactions Division, Rothamsted Research, Harpenden, AL5 2JQ, UK
Barley mild mosaic virus (BaMMV) is one of the most important diseases of winter barley causing large losses to crops in Europe and East Asia. The virus causes systemic mosaic symptoms on infected plants, typically seen as pale green or yellow streaking on the youngest leaves. BaMMV is transmitted to plants through the roots by the vector, Polymyxa graminis Led. BaMMV contains positive sense single-stranded RNA, packaged in flexuous filamentous particles. The BaMMV genome is bipartite consisting of RNA1 and RNA2. Little work has been done to understand BaMMV, movement (within barley plants) or transmission by P. graminis. The aim of this study is to gain an understanding of the various functions of the BaMMV viral genome, and to study virus-Polymyxa vector interactions. Vector and mechanical inoculations of a UK BaMMV isolate to a susceptible barley cultivar were carried out, and first symptoms were observed after six and two weeks respectively. BaMMV isolate was purified and cloned into the plasmid pCR-XL-TOPO, this work was done in the first year. Subsequently, full length cDNAs of BaMMV (RNA1 and RNA2) have been modified and produced clones, which contain a SP6 promoter at the 5’-end and a poly (A) tail at the 3’-end on each cDNA. BaMMV clones are currently being tested for infectivity and the results have been mixed. In addition, antibody to coat protein is being used to track the virus in the roots of infected plants by immunofluorescence or immunogold labelling.