Molecular variability of watermelon mosaic virus isolates from Argentina

POZZI, E.; MANGLLI, A.; TOMASSOLI, L.; PEROTTO, M. C.; LUCIANI, C.; BERTIN, S.; CONCI, V. C.

EUROPEAN JOURNAL OF PLANT PATHOLOGY

SPRINGER

Lugar: Berlin; Año: 2020 vol. 156 p. 1091 - 1099

0929-1873

Watermelon mosaic virus (WMV) is aneconomically important virus of cucurbit crops inArgentina. The available information on genetic variabilitymust be continuously updated. In this study,we assessed the molecular variability of WMV isolatesin Argentina based on the partial sequences ofthe NIb-CP region and compared them with isolatespreviously reported from around the world. FortysixWMV isolates were obtained from naturally infectedcucurbit crops collected from 10 provincesbetween 2011 and 2018. At the molecular level,WMV isolates were grouped into three distinct majorphylogenetic groups based on genetic distance.Majority of the Argentine isolates belonged to theemerging group (G3), whereas one isolate was includedin G1 and another cluster in G2. G3 wasfurther divided into 5 subgroups, named EM1,EM2, EM3, EM4, and a new group ?EMArg?, composedexclusively of Argentine isolates with highbootstrap support and high level of significance.Tajima?s D and Fu were significantly negative forG3 and EMArg, indicating that the population ofthis subgroup has recently expanded. AMOVA analysisshowed that the isolates was not well correlatedwith their geographic origin. The fixation index(FST) value between the WMV isolates from thedifferent provinces in Argentina was lower than0.33, indicating a relatively frequent gene flow betweenprovinces. In every group, the predominantevolutionary pressure was negative with a mean dN/dS < 1, suggesting a slow replacement fixation rate.One recombination event was detected involvingisolates of EM2 cluster from Argentina.