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The complete genome sequence of a German isolate of celery mosaic virus (CeMV, a potyvirus) from Quedlinburg (DSMZ PV-1003) was determined (MF962880). This represents the second fully sequenced genome of this virus, along with a Californian isolate (HQ676607.1). The positive-sense single-stranded RNA is 10,000 nucleotides in length and shows the typical organization of potyviruses but has a shorter PIPO than CeMV California. In comparison to CeMV isolates from different origins, CeMV-Quedlinburg and isolates from the Netherlands (AF203531.1) and Aschersleben, Germany (AJ271087.1) show a NAG instead of DAG in the region of the coat protein responsible for aphid transmission. In this study the first infectious full-length clone of celery mosaic virus was obtained and the infectivity confirmed by Rhizobium radiobacter infiltration of Apium species.

Inosine is deaminated adenosine. Inosine is enzymatically introduced in some plant tRNAs but not in other RNAs or DNA. Nonetheless, our data show that RNA and DNA from Arabidopsis thaliana contain (deoxy)inosine, probably derived from non-enzymatic adenosine deamination in nucleic acids and usage of (deoxy)inosine triphosphate (ITP / dITP) during nucleic acid synthesis. We identified a plant INOSINE TRIPHOSPHATE PYROPHOSPHATASE (ITPA) which is conserved in many organisms. Arabidopsis ITPA dephosphorylates deaminated nucleoside di- and triphosphates to their respective monophosphates. ITPA mutation causes inosine di- and triphosphate accumulation in vivo and an elevated (deoxy)inosine content in DNA and RNA. Cadmium-induced oxidative stress, known to foster deamination, leads to more ITP in the wildtype and especially in itpa mutants suggesting that ITP originates from ATP deamination. By contrast, erroneous IMP phosphorylation by AMP kinases seems not to be a major ITP source in vivo although these enzymes phosphorylate IMP in vitro. Mutation of ITPA causes salicylic acid (SA) accumulation, early senescence and upregulation of transcripts associated with immunity and senescence. ITPA is part of a molecular protection system, preventing accumulation of (d)ITP, its usage for nucleic acid synthesis, and probably nucleic acid stress leading to SA accumulation, stress gene induction and early senescence.

Cucumber vein yellowing virus (CVYV) is a member of the genus Ipomovirus in the family Potyviridae. In the National Center for Biotechnology Information (NCBI) database, three complete genome sequences of CVYV isolates from Spain (NC_006941), Israel (KT276369), and Jordan (JF460793) are available. In this study, we report the complete sequence of an isolate of CVYV from Portugal (DSMZ PV-0776) along with the construction of an infectious full-length cDNA clone via Gibson assembly. The sequence of CVYV Portugal shows the closest relationship to a CVYV isolate from Spain (genome, 99.7% identity; polyprotein, 99.7% identity). The CVYV full-length cDNA clone was introduced by electroporation into Rhizobium radiobacter and infiltrated into the cotyledons of Cucumis sativus plantlets, resulting in symptoms resembling those of the wild-type virus. Transmission of the infectious CVYV full-length clone by the whitefly Bemisia tabaci was confirmed. This first report confirming the infectivity of a CVYV cDNA clone provides the opportunity to study gene functions in a consistent genomic background.