Molecular characterization of a novel cryptic virus infecting pigeonpea plants

PLoS One. 2017 Aug 3;12(8):e0181829. doi: 10.1371/journal.pone.0181829. eCollection 2017.

Abstract

A new member of the genus Deltapartitivirus was identified containing three dsRNAs with an estimated size of 1.71, 1.49 and 1.43 kb. The dsRNAs were extracted from symptomless pigeonpea [Cajanus cajan (L.) Millspaugh] plants cv. Erra Kandulu. This new virus with 4.64 kb genome was tentatively named Arhar cryptic virus-1 (ArCV-1). The genomic RNAs were amplified and characterized by sequence independent single primer amplification. The dsRNAs shared a highly conserved 16 nt 5' non-coding region (5'-GATAATGATCCAAGGA-3'). The largest dsRNA (dsRNA-1) was identified as the viral RNA dependent RNA polymerase (replicase), predicted to encode a putative 55.34 kDa protein (P1). The two other smaller dsRNAs (dsRNA-2 and dsRNA-3) predicted to encode for putative capsid proteins of 38.50kDa (P2) and 38.51kDa (P3), respectively. Phylogenetic analysis indicated that ArCV-1 formed a clade together with Fragaria chiloensis cryptic virus, Rosa multiflora cryptic virus and Rose cryptic virus-1, indicating that ArCV-1 could be a new member of the genus Deltapartitivirus. ArCV-1 3Dpol structure revealed several interesting features. The 3Dpol in its full-length shares structural similarities with members of the family Caliciviridaeand family Picornaviridae. In addition, fourth dsRNA molecule (dsRNA-2A), not related to ArCV-1 genome, was found in the same plant tissue. The dsRNA-2A (1.6 kb) encodes a protein (P4), with a predicted size of 44.5 kDa. P4 shares similarity with coat protein genes of several cryptic viruses, in particular the bipartite cryptic viruses including Raphanus sativus cryptic virus-3. This is the first report of occurrence of a cryptic virus in pigeonpea plants.

MeSH terms

  • Amino Acid Motifs
  • Amino Acid Sequence
  • Base Sequence
  • Cajanus / virology*
  • Genomics
  • Models, Molecular
  • Plant Viruses / enzymology
  • Plant Viruses / genetics
  • Plant Viruses / physiology*
  • RNA, Viral / genetics
  • RNA-Dependent RNA Polymerase / chemistry
  • RNA-Dependent RNA Polymerase / metabolism

Substances

  • RNA, Viral
  • RNA-Dependent RNA Polymerase

Grants and funding

A fellowship to SK from the Indian Council of Medical research (ICMR), Govt. of India; grant number 45/59/2012PHA/BMS and financial support from Council of Scientific & Industrial Research are duly acknowledged. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.