Epsilon Archive for Student Projects

Abstract

Among the wheat diseases, wheat dwarf caused by Wheat dwarf virus (WDV) has resulted in damage to wheat production in the past years. This virus from the family Geminiviridae and genus Mastrevirus is transmitted by the leafhopper Psammotettix alienus. It has a genome of single stranded DNA (ssDNA) which can be replicated by means of the host replication system. Plants use several mechanisms to confront virus infection, including RNA silencing, hypersensitive response (HR) and DNA methylation. The intention of the study was to identify resistance/tolerance or reduced susceptibility against WDV in wild ancestors of wheat (Triticum spp. and Aegilops spp.), collected from the Middle East, which are supposed to carry resistance or tolerance against WDV. It was hypothesized that there are differences in susceptibility to WDV among wheat and its ancestors. During the domestication of wheat, the resistance genes may have been lost if there was no selection for them. To start, plants from three species (T. aestivum, T. urartu, Ae. tauschii) were inoculated with WDV using viruliferous leafhoppers (collected from WDV-affected fields close to Uppsala) in two experiments. After the inoculation period, the samples were harvested at different time points. The leaf tissues from the collected samples were tested by Double antibody sandwich ELISA (DAS-ELISA) to determine the virus titer. The result of DAS-ELISA on both source plants and samples revealed that since not all the leafhoppers were viruliferous, the inoculation tests were not successful and the hypothesis could not be tested properly. However, it was confirmed that T. urartu and Ae. tauschii are susceptible to WDV infection. The source plants were tested for WDV infection by PCR and RCA which did not show WDV infection in all of them. The virus isolate was also sequenced and compared with the GenBank database. The result confirmed that the virus isolates used for virus transmission were typical for the WDV wheat strain, with 99% nucleotide identity to the isolate Enköping 1 (Accession number AJ311031.1, GenBank).