Complete genome sequence of lettuce chordovirus 1 isolated from cultivated lettuce in France

Carrot populations in France and Spain host a complex virome rich in previously uncharacterized viruses

High-throughput sequencing (HTS) has proven a powerful tool to uncover the virome of cultivated and wild plants and offers the opportunity to study virus movements across the agroecological interface. The carrot model consisting of cultivated (Daucus carota ssp. sativus) and wild carrot (Daucus carota ssp. carota) populations, is particularly interesting with respect to comparisons of virus communities due to the low genetic barrier to virus flow since both population types belong to the same plant species. Using a highly purified double-stranded RNA-based HTS approach, we analyzed on a large scale the virome of 45 carrot populations including cultivated, wild and off-type carrots (carrots growing within the field and likely representing hybrids between cultivated and wild carrots) in France and six additional carrot populations from central Spain. Globally, we identified a very rich virome comprising 45 viruses of which 25 are novel or tentatively novel. Most of the identified novel viruses showed preferential associations with wild carrots, either occurring exclusively in wild populations or infecting only a small proportion of cultivated populations, indicating the role of wild carrots as reservoir of viral diversity. The carrot virome proved particularly rich in viruses involved in complex mutual interdependencies for aphid transmission such as poleroviruses, umbraviruses and associated satellites, which can be the basis for further investigations of synergistic or antagonistic virus-vector-host relationships.

Molecular and Biological Characterization of Novel and Known Family Secoviridae Members Infecting Lettuce

High-throughput sequencing of two lettuces showing virus-like symptoms in France provided evidence of infection by members of the family Secoviridae. One plant (JG1) had a complex mixed infection that involved, among others, a novel waikavirus (lettuce waikavirus 1) and two isolates of a sequivirus related to lettuce mottle virus (LeMoV). The second lettuce plant (JG2) was singly infected by LeMoV. Complete genomic sequences were obtained for all four isolates and, in addition, near complete genome sequences were obtained for other LeMoV or LeMoV-related isolates (from French cultivated and wild lettuces and from a Brazilian cultivated lettuce) and for two isolates of another family Asteraceae-infecting sequivirus, dandelion yellow mosaic virus (DaYMV). Analysis of these genomic sequences allows the proposal of tentative genome organization for the various viruses and clarification of their phylogenetic relationships. Sequence and host range comparisons point to significant differences between the two sequivirus isolates identified in the JG1 plant and LeMoV isolates from France and Brazil, suggesting they belong to a novel species for which the name lettuce star mosaic virus is proposed.

A new potyvirus from hedge mustard (Sisymbrium officinale (L.) Scop.) sheds light on the evolutionary history of turnip mosaic virus

A novel potyvirus was identified in symptomatic hedge mustard (Sisymbrium officinale (L.) Scop.) and wild radish (Raphanus raphanistrum L.) in France. The nearly complete genome sequence of hedge mustard mosaic virus (HMMV) was determined, demonstrating that it belongs to a sister species to turnip mosaic virus (TuMV). HMMV readily infected several other members of the family Brassicaceae, including turnip, shepherd's purse (Capsella bursa-pastoris), and arabidopsis. The identification of HMMV as a Brassicaceae-infecting virus closely related to TuMV leads us to question the current scenario of TuMV evolution and suggests a possible alternative one in which transition from a monocot-adapted ancestral lifestyle to a Brassicaceae-adapted one could have occurred earlier than previously recognized.Please check and confirm that the authors and their respective affiliations have been correctly identified and amend if necessary.all OK.