Lenardon, S. | Search bioRxiv

bioRxiv2019

Phylodynamics of sunflower chlorotic mottle virus, a re-emerging pathosystem

Distribution and epidemiological patterns of sunflower chlorotic mottle virus (SCMoV) in sunflower (Helianthus annuus L.) growing areas in Argentina were studied from 2006 to 2017. The virus was detected exclusively in the Pampas region (Entre Rios, Santa Fe, Cordoba, La Pampa and Buenos Aires provinces). Phylodynamic analyses performed using the coat protein gene of SCMoV isolates from sunflower and weeds dated the most recent common ancestor (MRCA) back to 1887 (HPD95% = 1572-1971), which coincides with the dates of sunflower introduction in Argentina. The MRCA was located in the south of Buenos Aires province and was associated with sunflower host (posterior probability for the ancestral host, ppah= 0.98). The Bayesian phylodynamic analyses revealed the dispersal patterns of SCMoV, suggesting a link between natural host diversity, crop displacement by human activities and virus spread.

plant biology↗

bioRxiv2019

Redefining the medicago sativa alphapartitivirus genome sequences

In alfalfa samples analyzed by hightroughput sequencing, four de novo assembled contigs encoding gene products showing identities to alphapartitiviruses proteins were found based on BlastX analysis. The predicted amino acid (aa) sequences of two contigs presented 99-100% identity to the RNA-dependent RNA polymerase (RdRp) and the capsid protein (CP) of the recently reported medicago sativa alphapartitivirus 1 (MsAPV1). In addition, the remaining two contigs shared only 56% (CP) and 70% (RdRp) pairwise aa identity with the proteins of MsAPV1, suggesting that these samples presented also a novel Alphapartitivirus species. Further analyses based on complete genome segments termini and the presence/absence of alphapartitivirus RNA in several samples and public alfalfa RNA datasets corroborated the identification of two different alphapartitivirus members. Our results also likely indicate that the reported MsAPV1 genome was previously reconstructed with genome segments of two different alphapartitiviruses. Overall, we not only revisited the MsAPV1 genome sequence but also report a new tentative alphapartitivirus species, which we propose the name medicago sativa alphapartitivirus 2. In addition, the RT-PCR detection of both MsAPV1 and MsAPV2 in several alfalfa cultivars suggests a broad distribution of both viruses.

microbiology↗