Complete genome sequence of a highly divergent carrot torradovirus 1 strain from Apium graveolens
A new virus was identified in a celery plant showing chlorotic rings, mosaic and strong yellowing symptoms, and its complete genome sequence was determined. The genomic organization of this novel virus is analogous to that of known members of the genus Torradovirus, consisting of two single-stranded RNAs of 6,823 (RNA1) and 4,263 nucleotides (RNA2), excluding the poly(A) tails. BLAST searches against the nucleotide and protein databases showed that this virus is closely related to but different from carrot torradovirus 1 (CaTV1). Comparisons between the two viruses demonstrated relatively low levels of nucleotide and amino acid similarity in different parts of their genomes, as well as considerable differences in the sizes of their two genomic RNAs. However, the protease-polymerase (Pro-Pol) and capsid protein (CP) regions of this virus share >80% amino acid identity with the corresponding regions of CaTV1. Therefore, based on the current ICTV species demarcation criteria for the family Secoviridae, the virus from celery is a divergent strain of CaTV1, named “CaTV1-celery”. Nevertheless, differences between CaTV1 and CaTV1-celery in genome size, as well as in biological and epidemiological features, may warrant their separation into two distinct species in the future.
The authors thank Ms. Roswitha Ulrich for providing the original sample. The authors are grateful to Ms. Angelika Sieg-Müller, Ms. Petra Lüddecke, Ms. Kerstin Herz and Mr. Jonas Hartrick for their outstanding technical assistance, and Mr. Christopher Ziebell for proofreading.
This research was financed by EUPHRESCO (2015-F-172) project “The Application of Next-Generation Sequencing Technology for the Detection and Diagnosis of Non-culturable Organisms: Viruses and viroids”. Yahya Z. A. Gaafar was supported by a German Egyptian Research Long Term Scholarship.
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Conflict of interest
The authors declare that they have no conflict of interest.
This research did not involve any studies on human or animal participants.
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