A new member of the family Closteroviridae identified from symptomatic kiwifruit (Actinidia spp) plants showing multiple viral infection.

Kiwifruit is an important crop in China, Italy, New Zealand and Chile that collectively contribute for 80% of the world's production. Recent studies demonstrated that Actinidia spp. can be infected by a wide range of pathogens and currently twelve different viral species have been identified on kiwifruit plants. Our studies recently focused on plants of A. chinensis cv Hort 16A showing chlorotic and necrotic rings on leaves followed by a general decline and Death of the scion but not of the rootstock (A. deliciosa cv. Hayward). Pelargonium zonate spot virus, Actinidia virus A, and Actinidia virus B viruses have been detected in samples analyzed and etiology dissection of this complex disorder has been investigated by next Generation sequencing approach. De-novo assembly of raw data from 454 Illumina and Ion Torrent platforms generated a sequence of about 17 kb containing one large ORF carrying two papain-like leader proteases, the methyltransferase, the elicase and the RNA-dependent RNA polymerase. Additional ORFs contain homologues to a heat shock protein 70, a heat shock protein 90, and a silencing suppressor protein and a minor coat protein. However no homologue of a major coat protein has been detected. The genomic organization and the phylogenetic analysis showed that this sequence is related to the olive leaf yellow associated virus, a tentative member of the closterovirus genus. The sequence has been confirmed by cloning of overlapping fragments sequenced by the classical Sanger sequencing. The new viral species identified contributes to the understanding of a disorder observed that has already been associated with significant consequences for yield on kiwifruit plants.