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Chickpea chlorotic stunt virus: A New Polerovirus Infecting Cool-Season Food Legumes in Ethiopia

First, second, third, and fifth authors: Federal Biological Research Center for Agriculture and Forestry (BBA), Institute of Plant Virology, Microbiology and Biosafety, Messeweg 11-12, 38104 Braunschweig, Germany; and fourth author: University of Göttingen, Institute of Plant Pathology and Plant Protection, Grisebachstr. 6, 37077 Göttingen, Germany

Serological analysis of diseased chickpea and faba bean plantings with yellowing and stunting symptoms suggested the occurrence of an unknown or uncommon member of the family Luteoviridae in Ethiopia. Degenerate primers were used for reverse transcriptase-polymerase chain reaction amplification of the viral coat protein (CP) coding region from both chickpea and faba bean samples. Cloning and sequencing of the amplicons yielded nearly identical (96%) nucleotide sequences of a previously unrecognized species of the family Luteoviridae, with a CP amino acid sequence most closely related (identity of ≈78%) to that of Groundnut rosette assistor virus. The complete genome (5,900 nts) of a faba bean isolate comprised six major open reading frames characteristic of polero-viruses. Of the four aphid species tested, only Aphis craccivora transmitted the virus in a persistent manner. The host range of the virus was confined to a few species of the family Fabaceae. A rabbit antiserum raised against virion preparations cross-reacted unexpectedly with Beet western yellows virus-like viruses. This necessitated the production of murine monoclonal antibodies which, in combination with the polyclonal antiserum, permitted both sensitive and specific detection of the virus in field samples by triple-antibody sandwich, enzyme-linked immunosorbent assay. Because of the characteristic field and greenhouse symptoms in chickpea, the name Chickpea chlorotic stunt virus is proposed for this new member of the genus Polerovirus (family Luteoviridae).

Additional keywords: aphid transmission, decoration titer, electron microscopy, sequence analysis, Turnip yellows virus.