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Title: The genetic diversity of Turnip yellows virus in oilseed rape (Brassica napus) in Europe : pathogenic determinants, new sources of resistance and host range
Author: Newbert, Max John
ISNI:       0000 0004 5924 2581
Awarding Body: University of Warwick
Current Institution: University of Warwick
Date of Award: 2016
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The aphid transmitted Polerovirus Turnip yellows virus (TuYV) was found to be widespread with high incidences in oilseed rape (OSR) across Europe. UK, France, Germany and Poland all having >90% TuYV incidence in some OSR crops. From the 179 whole TuYV genomes sequenced in this study the phylogenetic analyses indicated three distinct genetic groups in the UK, two of which were also detected in Europe. These three genotypes were also distinct from the original sequenced TuYV-FL. These groups are proposed to be distinct species due to their genetic distance based on the most variable gene ORF5 and phylogenetic analyses of ORF1, ORF3, ORF4 and ORF5. Mixed TuYV infection was uncommon and only two plant samples had genetically distinct isolates. Whole genome analysis also provided valuable information on two recombination hotspots located within TuYV genes ORF3 and ORF5. Investigation into the epidemiology of TuYV revealed many weed and crop species as hosts, including sugar beet, which it was previously thought not to infect. TuYV isolates detected infecting weed plants in the UK were successfully transmitted to OSR. Previously undescribed hosts, verbascum, geranium, teasel, spear thistle, dock and previously described hosts in the Brassicaceae, Compositae and Lepidium families were found in the UK. A full-length infectious clone of a UK isolate of TuYV has been produced, this will allow further assessment of TuYV in the future. The infectious clone was able to cause systemic infection of TuYV and was aphid transmissible. The Arabidopsis thaliana gene knock-out study did not reveal a single eIF gene or gene linked to virus movement or silencing that could provide extreme broad-spectrum resistance. The gene eIF(iso)4G.1 was able to give a broad-spectrum quantitative resistance, and the potential of eIF3D.2 as well as sucrose symporters SUC1 and SUC2 as candidates for extreme TuYV resistance were discovered. This understanding of the epidemiology and diversity of TuYV is being used to develop strategies for control.
Supervisor: Not available Sponsor: Biotechnology and Biological Sciences Research Council (BBSRC) ; Perry Foundation
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: QR355 Virology ; SB Plant culture