Sixty Years After the First Description: Genome Sequence and Biological Characterization of European Wheat Striate Mosaic Virus Infecting Cereal Crops

Abstract

High-throughput sequencing technologies were used to identify plant viruses in cereal samples surveyed from 2012 to 2017. Fifteen genome sequences of a tenuivirus infecting wheat, oats, and spelt in Estonia, Norway, and Sweden were identified and characterized by their distances to other tenuivirus sequences. Like most tenuiviruses, the genome of this tenuivirus contains four genomic segments. The isolates found from different countries shared at least 92% nucleotide sequence identity at the genome level. The planthopper Javesella pellucida was identified as a vector of the virus. Laboratory transmission tests using this vector indicated that wheat, oats, barley, rye, and triticale, but none of the tested pasture grass species (Alopecurus pratensis, Dactylis glomerata, Festuca rubra, Lolium multiflorum, Phleum pratense, and Poa pratensis), are susceptible. Taking into account the vector and host range data, the tenuivirus we have found most probably represents European wheat striate mosaic virus first identified about 60 years ago. Interestingly, whereas we were not able to infect any of the tested cereal species mechanically, Nicotiana benthamiana was infected via mechanical inoculation in laboratory conditions, displaying symptoms of yellow spots and vein clearing evolving into necrosis, eventually leading to plant death. Surprisingly, one of the virus genome segments (RNA2) encoding both a putative host systemic movement enhancer protein and a putative vector transmission factor was not detected in N. benthamiana after several passages even though systemic infection was observed, raising fundamental questions about the role of this segment in the systemic spread in several hosts.

Is There a “Biological Desert” With the Discovery of New Plant Viruses? A Retrospective Analysis for New Fruit Tree Viruses

“…For example, HTS data sharing allowed for a better understanding of the geographical spread of a new closterovirus (Koloniuk et al, 2018b). The pre-publication data sharing could also include biological experiments, as was recently shown for the European wheat striate mosaic virus (Sõmera et al, 2020). Overall, pre-publication data sharing enables better risk evaluation and can limit the risks of unnecessary regulatory action.…”

The Bunyavirales: The Plant-Infecting Counterparts

“…In older literature, many of these (non-structural (NS)) protein genes were often referred to as NS (v-strand encoded) or NSvc (vc-strand encoded)). The pV1 protein of EWSMV, but not of RGSV, presents a domain similar to plant NAC-like transcription factors that regulates genes involved in plant development and in responses to biotic and abiotic stresses [ 17 ].…”

“…They generally induce the formation of white or yellow “stripes” in the leaves of infected plants, and they can severely reduce crop yield [ 16 ]. Tenuivirus-like disease symptoms have been observed in cereal crops for more than a century, whereas, in some of these cases, the role of a tenuivirus as the disease agent has only recently been confirmed [ 13 , 15 , 17 ].…”

The Plant Negative-Sense RNA Virosphere: Virus Discovery Through New Eyes

“…The application of HTS led to the discovery of two new tenuiviruses, one infecting melon and black medic (Gaafar et al, 2019a;Lecoq et al, 2019) and the other from sugarcane associated with Ramu stunt disease (Mollov et al, 2016) (Table 1). In addition, a recent HTS study resulted in the molecular characterization of a wheat tenuivirus, the biological properties of which had been previously characterized in the 1960s (Sõmera et al, 2020) (Table 1). Total RNA and small RNAs were used as sources for HTS on Illumina platforms (Table 1).…”