ISHS Acta Horticulturae 668: I International Humulus Symposium
STUDY OF INFECTION AND SEQUENCE VARIABILITY OF VIROIDS IN THE CZECH REPUBLIC |
| Authors: | J. Matoušek, L. Orctová, J. Patzak, P. Svoboda, K. Krofta |
| Keywords: | hop, hop stunt viroid, hop latent viroid, RNA isolation, Dot-blot molecular, hybridization, RT-PCR, thermomutants |
| Abstract:
Two viroids, the smallest pathogenic RNA replicons, occur in hop plants: hop stunt viroid (HSVd) and hop latent viroid (HLVd). The HLVd pathogen is distributed worldwide. RNA isolation from hop tissues, which are rich in polyphenolics, polysaccharides and other secondary metabolites (bitter acids, essential oils), is necessary for viroid detection in hop plants by Dot-blot molecular hybridization and RT-PCR. ConcertTM Plant RNA reagent (Invitrogen, USA) was the best RNA isolation method for all molecular detection methods. The incidence of viroids in Czech hop gardens was characterized. We found that 100% and 0% of hop samples were infected with HLVd and HSVd, respectively. We found that at least 70% of grapevine samples from locations close to hop gardens were infected with HSVd forming populations with dominant HSVdg variant corresponding to AC E01844. HSVd was experimentally transmissible (80% efficiency) from these samples to Czech hop Osvald's clone 72. We also observed increasing levels of mutated variants in HLVd under heat stress cultivation conditions. Experimental virus and viroid free hop plants were infected with 8 specific “thermomutants” and studied in field conditions over three years. Decreases in alpha acids and changes in the secondary metabolites contents were associated with viroid infection. | |
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