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Genetic Variability, Evolution, and Biological Effects of Grapevine fanleaf virus Satellite RNAs

November 2013 , Volume 103 , Number  11
Pages  1,180 - 1,187

J. Gottula, D. Lapato, K. Cantilina, S. Saito, B. Bartlett, and M. Fuchs

Department of Plant Pathology and Plant-Microbe Biology, Cornell University, New York State Agricultural Experiment Station, Geneva, NY 14456.

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Accepted for publication 23 May 2013.

Large satellite RNAs (type B satRNAs) of Grapevine fanleaf virus (GFLV) from the genus Nepovirus, family Secoviridae were identified in a naturally infected vineyard and a grapevine germplasm collection. These GFLV satRNA variants had a higher nucleotide sequence identity with satRNAs of Arabis mosaic virus (ArMV) strains NW and J86 (93.8 to 94.6%) than with the satRNA of GFLV strain F13 and those of other ArMV strains (68.3 to 75.0%). Phylogenetic analyses showed no distinction of GFLV and ArMV satRNAs with respect to the identity of the helper virus. Seven stretches of 8 to 15 conserved nucleotides (I-VII) were identified in the 5′ region of subgroup A nepovirus genomic RNAs GFLV, ArMV, and Grapevine deformation virus) and nepovirus type B satRNAs, including previously reported motif I, suggesting that large satRNAs might have originated from recombination between an ancestral subgroup A nepovirus RNA and an unknown RNA sequence with the 5′ region acting as a putative cis-replication element. A comparative analysis of two GFLV strains carrying or absent of satRNAs showed no discernable effect on virus accumulation and symptom expression in Chenopodium quinoa, a systemic herbaceous host. This work sheds light on the origin and biological effects of large satRNAs associated with subgroup A nepoviruses.

Additional keywords: commensalism, genetic distance, plant virus symptoms, Vitis vinifera.

© 2013 The American Phytopathological Society