HOST RANGE, INCIDENCE AND GENETIC VARIABILITY OF watermelon mosaic virus IN CENTRAL SPAIN
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Date
2018-01
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Publisher
AAU, Jorhat
Abstract
Watermelon mosaic virus (WMV, Potyvirus) is an economically important pathogen
common in cucurbits of temperate and Mediterranean regions worldwide. The presence of
WMV in cucurbits in the Mediterranean basin has been known for decades. More recently, an
emergent strain that causes more severe symptoms compared to classic strains has been
recognized in France. The cultivation of melon is threatened by the spread of emergent
strains of WMV. Diagnostic methods for detecting the host range, incidence and evolution of
these emergent types are critical for developing control strategies to optimize agricultural
production. In this study, next generation sequencing and RT-PCR approaches are combined
to investigate the epidemiology of WMV in an agro-ecosystem of Central Spain. Four
vegetation types, or habitats, including cultivated and adjacent land-use types were surveyed
in the summer and autumn of 2015. Forty-three plant species were screened for WMV, 15 of
which were WMV-positive across two habitats other than crops. The results indicated an
increase in the extent of the WMVs known host range. The incidence of WMV ranged from
64% in Cucumis melo to 5% in a weed species, Datura Stramonium. Genetic analyses of the
coat protein gene of 30 isolates from melon and 3 other ‘weed’ species sampled in crops
showed population variation in nucleotide diversity, but pairwise fixation indices indicated
negligible distinctions between them. Phylogenetic inferences showed both negligible and
large branch length differences between isolates from different host species. When sequences
of a number of different strains were added to the isolates from the melon crops, one clad
clustered with an emergent group previously identified from elsewhere in Europe and Asia.
This study reports the first instance of an emerging (EM) strain in Central Spain.